Viscous fluid transfer apparatus and transfer method, electronic component mounting apparatus and mounting method, and semiconductor device Number:6,789,720 from the United States Patent and Trademark Office (PTO) owispatent

Title: Viscous fluid transfer apparatus and transfer method, electronic component mounting apparatus and mounting method, and semiconductor device

Abstract: A squeegee unit having a stirring squeegee and a leveling squeegee fixed thereto is rocked with the reciprocating operation of a transfer unit moving mechanism to cause the stirring squeegee and the leveling squeegee to approach the pan surface of a transfer unit on going and returning paths. Consequently, the stirring squeegee stirs a viscous fluid put on the transfer unit on the going path of the transfer unit and the leveling squeegee uniformly flattens the viscous fluid stirred on the going path to have a predetermined thickness on the returning path of the transfer unit, thereby forming a flat viscous fluid transfer surface on the transfer unit. By immersing the terminal portion of the electronic component in the viscous fluid transfer surface, the viscous fluid is transferred to the electronic component and the electronic component is then mounted in a predetermined mounting position.

Patent Number: 6,789,720 Issued on 09/14/2004 to Uchida,   et al.

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Inventors:	Uchida; Hideki (Kofu, JP), Kido; Kazuo (Kofu, JP), Nakano; Tomoyuki (Kofu, JP), Kuribayashi; Takeshi (Yamanashi, JP), Misawa; Yoshihiko (Katano, JP)
Assignee:	Matsushita Electric Industrial Co., Ltd. (Osaka, JP)
Appl. No.:	10/016,455
Filed:	December 10, 2001

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Foreign Application Priority Data

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Dec 11, 2000 [JP]			P. 2000-376265

Current U.S. Class:	228/22 ; 228/102; 228/259; 228/8; 29/840
Field of Search:	228/19,22,180.22,223,8,102,259 29/840

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References Cited [Referenced By]

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U.S. Patent Documents

	5297333		March 1994		Kusaka
	5601229		February 1997		Nakazato et al.
	5680984		October 1997		Sakemi
	5783870		July 1998		Mostafazadeh et al.
	5791243		August 1998		Marcoux et al.
	6099681		August 2000		Arikado et al.
	6537400		March 2003		Fogal et al.
	6576495		June 2003		Jiang et al.
	6581282		June 2003		Mori et al.
	2004/0035306		February 2004		Onishi et al.

Foreign Patent Documents

	62 056145		Mar., 1987		JP
	06 238869		Aug., 1994		JP
	08 187836		Jul., 1996		JP
	11 198348		Jul., 1999		JP
	2001-267728		Sep., 2001		JP
	2001-339196		Dec., 2001		JP
	WO 00/05936		Feb., 2000		WO

Other References

IBM Technical Disclosure Bulletin, IBM Corp. New York, "Known Good Dye Test and Direct Chip Attach Assembly", Jul. 1, 1996, pp. 215, 217, vol. 39 No. 07..

Primary Examiner: Edmondson; L.
Attorney, Agent or Firm: Pearne & Gordon LLP

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Claims

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What is claimed is:

1. An electronic component mounting apparatus for sucking and holding an electronic component and mounting the electronic component into a predetermined mounting position, said apparatus comprising: an electronic component supply device for supplying a plurality of electronic components to supply a desirable one of said electronic components; a sucking nozzle for removably sucking and holding said electronic component; an attachment head for holding said sucking nozzle to rise and fall freely; a head moving device for moving said attachment head in a horizontal plane; and a viscous fluid transfer device for forming a flat viscous fluid transfer surface for transferring viscous fluid to a connecting terminal of an electronic component and for uniformly flattening a viscous fluid on a transfer unit to form a flat viscous fluid transfer surface, wherein said viscous fluid transfer device including a transfer unit having a planar pan surface for putting a viscous fluid thereon, a squeegee unit having a stirring squeegee shaped planar for stirring said viscous fluid put on said pan surface, a leveling squeegee shaped planar for uniformly flattening said viscous fluid which is stirred, and a squeegee fixing member serving to separate said stirring squeegee and said leveling squeegee from each other and to fix them in parallel, wherein both ends of said fixing member are supported pivotally and rockably above said transfer unit, a transfer unit moving mechanism for reciprocating said transfer unit such that said stirring squeegee and said leveling squeegee are relatively moved each other along the planar pan surface of said transfer unit, and a squeegee driving mechanism for rocking said squeegee unit such that said stirring squeegee approaches said pan surface on going path of said stirring squeegee and said leveling squeegee approaches said pan surface on returning path of said leveling squeegee, wherein said electronic component sucked by said electronic component supply member is moved onto said transfer unit of said viscous fluid transfer device and a terminal portion of said electronic component is immersed in said viscous fluid transfer surface by said up-down operation of said attachment head, thereby transferring said viscous fluid to said electronic component.

2. The electronic component mounting apparatus according to claim 1, wherein said attachment head includes: a rubber pad provided in a tip portion of said sucking nozzle and having a sucking surface which can be inclined freely and can be expanded and contracted freely in a direction of suction; and a sucking attitude correcting member provided around said rubber pad in which a tip portion has a contact face to contact on a rear face of said electronic component during said suction of the electronic component.

3. The electronic component mounting apparatus according to claim 2, wherein said sucking attitude correcting member is constituted of a pair of rod bodies provided on both sides of said rubber pad.

4. The electronic component mounting apparatus according to claim 2, wherein said contact face of said sucking attitude correcting member is formed to be inclined from a horizontal plane.

5. The electronic component mounting apparatus according to claim 1 further comprising: a multi-head having a plurality of said attachment heads arranged in parallel, and wherein said transfer unit of said viscous fluid transfer device including a pan surface having a greater width than that of said multi-head.

6. The electronic component mounting apparatus according to claim 5, wherein the transfer unit includes a pan surface having a greater width than a double of the width of the multi-head.

7. An electronic component mounting method of mounting an electronic component in a predetermined mounting position, comprising the steps of: sucking an electronic component by an attachment head having a sucking nozzle, while uniformly flattening a viscous fluid on a transfer unit having a planar pan surface to form a viscous fluid transfer surface; moving the sucked attachment head of the electronic component to an upper position of the viscous fluid transfer surface; bringing down the sucking nozzle until a terminal portion of the electronic component is immersed in the viscous fluid transfer surface; raising the sucking nozzle after transferring the viscous fluid to the electronic component and moving the attachment head to a predetermined mounting position; and bringing down the sucking nozzle in the mounting position, thereby mounting the electronic component, wherein a height of said viscous fluid transfer surface of said transfer unit is detected before the viscous fluid is transferred to the electronic component, and an amount of bringing down the sucking nozzle of the attachment head is set according to the detected height of said viscous fluid transfer surface of said transfer unit.

8. The electronic component mounting method according to claim 7, wherein said sucking nozzles of a multi-head including a plurality of attachment heads arranged in parallel are controlled to be brought up and down at the same time.

9. The electronic component mounting method according to claim 7, wherein said viscous fluid transfer surface is formed in a predetermined thickness on said transfer unit and said terminal portion of said electronic component is pushed to contact on the pan surface of the transfer unit, thereby transferring the viscous fluid having the predetermined thickness to the electronic component.

10. The electronic component mounting method according to claim 7, wherein the viscous fluid is transferred to a second electrical component, and wherein said second electrical component is stacked and mounted on a rear face opposite to a mounting surface side of a first electronic component which has already been mounted on a circuit board.

11. The electronic component mounting method according to claim 10, further comprising the steps of: detecting a reference mark for alignment provided on a rear face of said first electronic component, correcting a mounting position of said second electronic component by setting said reference mark as a reference.

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Description

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a viscous fluid transfer apparatus and method for transferring a viscous fluid to the connecting terminal of a package component such as an IC. The present invention also relates to an electronic component mounting apparatus and method using the viscous fluid transfer apparatus, and a semiconductor device. Moreover, the present invention particularly relates to a three-dimensional mounting technique for providing an electronic component in plural stages.

2. Description of the Related Art

In the recent electronic apparatus industry, a high functionality and a reduction in a size and a weight of a product have been vigorously developed, and various mounting methods such as double-sided mounting have been employed for an electronic component such as an IC in order to reduce a mounting area to a circuit board in addition to an increase in the integration of a semiconductor device itself.

In the package technique of the electronic component, moreover, a DIP (Dual Inline Package) which has conventionally been used widely is switched to a QFP (Quad Flat Package) and an SOP (Small Outline Package) which have a space between leads as shown in a double-sided mounting state of FIG. 58(a), and furthermore, attention has been paid to an area array type package such as a BGA (Ball Grid Array) or a CSP (Chip Size Package) shown in FIG. 58(b) as a technique for a practical stage.

On the other hand, a bare chip mounting method for carrying out direct mounting onto a circuit board without packaging has also been partially employed. However, there has still been a problem to be solved for a mass production and a reduction in a cost. In the bare chip mounting method, a flux is transferred onto a bare chip component to be mounted on a circuit board. In this case, examples of a flux transfer device for transferring the flux include a device for forming the transfer surface of the flux by reciprocating a squeegee 512 having almost the same structure over a transfer unit 510 as shown in FIGS. 59(a), 59(b), 60(a), and 60(b). The bare chip component is mounted by moving the squeegee 512 over the transfer unit 510 to extend the flux over the whole pan surface and immersing the bare chip component on the extended flux to transfer the flux to the component side, and by pressure welding the bare chip component into a predetermined position on the circuit board after the transfer.

Moreover, there have been various methods for mounting the electronic component of the area array type package onto the circuit board, and the mounting can be carried out in the following manner, for example. First of all, a land is formed in a position on the circuit board corresponding to the solder ball of an electronic component (BGA) and a solder cream is mask printed on the land. Then, the electronic component is mounted in the predetermined position on the circuit board to superpose the printed solder cream on the solder ball of the electronic component, and the electronic component is temporarily fixed to the circuit board with the viscosity of the solder cream. The circuit board is subjected to a reflow process so that the solder cream and the solder ball are molten and the land and the solder ball of the electronic component are connected and fixed to each other.

In the mounting method for the electronic component of the conventional area array type package, however, a reduction in a mounting area has further been required. And furthermore, a mask hole forming technique having high precision for a solder cream printing screen and a mask aligning technique have been required with an enhancement in the fine pitch of the electronic component. For this reason, stable mounting having high precision has been restricted over the extension of a current method and it is inevitably hard to carry out further high density mounting so that the development of other different mounting methods has been desired.

A technique for forming an electronic component with a stack structure having several stages has variously been investigated. However, the electronic component is not simply stacked but a jig accommodating the electronic component therein is provided or a contact structure is very complicated. Consequently, there has been a problem in that the design of a conventional circuit pattern is forcibly changed considerably and a mounting cost is hard to reduce.

Moreover, it has also been supposed that the electronic component is three-dimensionally mounted by stack on a rear face opposite to the mounting surface side of the electronic component for an area array type package such as a BGA or a CSP having the small pitch of a connecting terminal. There has been a problem in that a method of giving a solder cream for the stack is to be established or alignment precision is to be maintained. Therefore, the practical use has not been attained.

When a solder cream is to be put and transferred onto the electronic component in place of the flux by using the flux transfer device for transferring the flux onto the bare chip component, the viscosity of the solder cream is extremely higher than that of the flux. Therefore, the solder cream overflows from the transfer unit so that the flux transfer device cannot be actually substituted for solder cream transfer.

FIGS. 59(a), 59(b), 60(a) and 60(b) show a state in which the solder cream is put onto the flux transfer device to move the squeegee 512, (a) being a plan view and (b) being a side view. As shown in FIGS. 59(a) and (b), when the squeegee 512 is moved from the left side to the right side in the drawing, the solder cream is protruded from the end in the longitudinal direction of the squeegee 512 based on a difference in a viscosity so that it overflows from the edge portion of the transfer unit 510. In the same manner as in FIGS. 60(a) and (b), when the squeegee 512 is moved from the right side to the left side in the drawing, the solder cream further overflows.

In addition, the solder cream coming in contact as shown in FIG. 61 is transmitted toward the upper part of each squeegee 512 due to a viscosity thereof, and finally, the solder cream sticks to each portion of the apparatus and the solder cream is dropped off from a part of the apparatus. As a result, the solder cream is scattered to the surrounding environment so that maintenance is often required. Consequently, a manufacturing man-hour is increased and the quality of a product is deteriorated.

Moreover, there is also a problem regarding a sucking nozzle 514 to be used for the transfer of the solder cream. More specifically, as shown in FIG. 62, when an electronic component 520 is to be pushed against an inclined surface, for example, the solder cream is to be transferred to the electronic component 520 by using the transfer unit 510 having the inclined pan surface, the sucking nozzle 514 usually has a sucking tip portion 514a formed of a metal and the rear face of the electronic component 520 is inclined. Therefore, a clearance is generated between the sucking tip portion 514a and the rear face of the electronic component 520 so that air leaks from the clearance and suction cannot be carried out.

It can be proposed that a component sucking property can be improved by attaching a rubber pad 516 to the sucking tip portion 514a. However, when the solder cream is to be transferred to the electronic component 520 as shown in FIG. 62, for example, the rubber pad 516 is elastically deformed and contracted in the direction of push-in so that a push-in depth cannot be controlled even if the electronic component 520 is pushed in from the surface of the solder cream up to a predetermined depth. Thus, if the solder cream cannot be given to the electronic component necessarily and sufficiently, connection cannot be carried out reliably so that the conduction failures of the electronic component after mounting or mechanical fixing failures might be caused.

The invention has been made in consideration of the conventional circumstances. It is the first object of the invention to provide a viscous fluid transfer apparatus and a transfer method for transferring a viscous fluid to the terminal portion of an electronic component and laminating an electronic component, in order to increase a space efficiency to mount an area array type package component to a circuit board at a high density.

Moreover, it is the second object of the invention to provide an electronic component mounting apparatus and a mounting method of laminating and mounting an electronic component onto a circuit board by using the viscous fluid transfer apparatus and the transfer method.

Furthermore, it is the third object of the invention to provide a semiconductor device capable of carrying out high density mounting as a stack structure having plural stages.

SUMMARY OF THE INVENTION

In order to achieve the objects, a first aspect of the invention is directed to a viscous fluid transfer apparatus for forming a flat viscous fluid transfer surface for transferring a viscous fluid to a connecting terminal of an electronic component. The viscous fluid transfer apparatus includes a transfer unit having a planar pan surface for putting a viscous fluid thereon, a squeegee unit having a planar stirring squeegee for stirring the viscous fluid put on the pan surface, a planar leveling squeegee for uniformly flattening the viscous fluid thus stirred, and a squeegee fixing member serving to separate the squeegees from each other and to fix them in parallel and having both ends rockably supported pivotally above the transfer unit, a transfer unit moving mechanism for reciprocating the transfer unit such that the squeegee is relatively moved along the pan surface of the transfer unit, and a squeegee driving mechanism for rocking the squeegee unit such that the stirring squeegee and the leveling squeegee approach the pan surface on going and returning paths, respectively.

The viscous fluid transfer apparatus rocks the squeegee unit having the stirring squeegee and the leveling squeegee fixed thereto with the reciprocating operation of the transfer unit moving mechanism through the squeegee driving mechanism, and to cause the stirring squeegee and the leveling squeegee to approach the pan surface of the transfer unit on going and returning paths, respectively. Consequently, the stirring squeegee stirs the viscous fluid over the transfer unit on the going path of the transfer unit and the leveling squeegee causes the viscous fluid stirred on the going path to uniformly have a predetermined thickness on the returning path of the transfer unit. As a result, the flat viscous fluid transfer surface is formed on the transfer unit.

A second aspect of the invention is directed to the viscous fluid transfer apparatus, further including a protrusion formed on a pan surface side of both ends in the longitudinal direction of the stirring squeegee, wherein the protrusion scrapes the viscous fluid put on the pan surface toward a central side in a longitudinal direction of the stirring squeegee.

In the viscous fluid transfer apparatus, when the stirring squeegee is relatively moved again after the leveling squeegee is relatively moved, the viscous fluid overflowing from both ends in the longitudinal direction of the leveling squeegee during the relative movement of the leveling squeegee at the last time can be scraped toward the central side in the longitudinal direction of the squeegee through a formed discharge portion. Thus, the viscous fluid can be prevented from overflowing from the pan surface of the transfer unit.

A third aspect of the invention is directed to the viscous fluid transfer apparatus, wherein the protrusion of the stirring squeegee has a taper face inclined in such a direction as to narrow a passage for the viscous fluid rearward from a front part in a direction of progress of the squeegee within a thickness of the squeegee.

In the viscous fluid transfer apparatus, the protrusion of the stirring squeegee has the taper face for reducing the flow of the viscous fluid. Consequently, the viscous fluid can be scraped toward the central side in the longitudinal direction of the squeegee along the taper face by the relative movement of the stirring squeegee on the transfer unit and the viscous fluid can overflow from the pan surface of the transfer unit with a simple structure.

A fourth aspect of the invention is directed to the viscous fluid transfer apparatus, further including an intermediate protrusion formed between the protrusions on both ends of the stirring squeegee, wherein the intermediate protrusion forms the viscous fluid put on the pan surface like a band.

In the viscous fluid transfer apparatus, the intermediate protrusion is formed between the protrusions. Consequently, when the stirring squeegee is relatively moved over the transfer unit, the viscous fluid is partially scraped by the intermediate protrusion. As a result, the viscous fluid is formed like a band over the transfer unit. Consequently, the viscous fluid is scraped from the lower surface of the transfer unit so that the stirring effect can be enhanced. When the next leveling squeegee is relatively moved, the viscous fluid formed like a band is flattened to have a uniform thickness so that an excellent viscous fluid transfer surface can always be obtained.

A fifth aspect of the invention is directed to the viscous fluid transfer apparatus, wherein the intermediate protrusion has a taper face inclined in such a direction as to narrow the passage for the viscous fluid rearward from the front part in the direction of progress of the squeegee within the thickness of the squeegee.

In the viscous fluid transfer apparatus, the intermediate protrusion has the taper face inclined in such a direction as to narrow the passage for the viscous fluid. Consequently, the viscous fluid is scraped along the taper face during the relative movement of the stirring squeegee so that the viscous fluid can be prevented from overflowing from the pan surface of the transfer unit.

A sixth aspect of the invention is directed to the viscous fluid transfer apparatus, wherein a concave sectional curved portion and a convex sectional curved portion are sequentially formed on the pan surface side of the leveling squeegee from the front part in the direction of progress of the squeegee.

In the viscous fluid transfer apparatus, when the leveling squeegee is relatively moved, the viscous fluid on the transfer unit is pressurized and extended in the tip portion of the convex sectional curved portion, and furthermore, the excessive viscous fluid is rolled in the concave sectional curved portion and is returned in the direction of progress of the squeegee. Consequently, it is possible to prevent the viscous fluid from being transmitted toward the upper part of the squeegee.

A seventh aspect of the invention is directed to the viscous fluid transfer apparatus, wherein a tip on the pan surface side of the leveling squeegee is formed to have a V-shaped section.

In the viscous fluid transfer apparatus, the tip on the pan surface side of the leveling squeegee is formed to have a V section which can easily be processed. Consequently, the shape of the tip portion of the squeegee can be simplified to reduce the manufacturing cost of the squeegee itself.

An eighth aspect of the invention is directed to the viscous fluid transfer apparatus, further including a corner portion formed in the middle of a inclined surface on a part in a direction of progress of the leveling squeegee, wherein the corner portion is protruded outward and formed over a longitudinal direction of the leveling squeegee, and wherein a section of the corner portion is an obtuse angle.

In the viscous fluid transfer apparatus, the corner portion is formed in the middle of the inclined surface of the leveling squeegee. Consequently, even if the viscous fluid is transmitted upward from the tip portion of the squeegee during the relative movement of the leveling squeegee, it falls down and is returned at the formed corner portion. Consequently, the viscous fluid can be prevented from excessively sticking to the squeegee.

A ninth aspect of the invention is directed to the viscous fluid transfer apparatus, further including a pressure generating member provided in the longitudinal direction of the leveling squeegee in the vicinity of a tip on the pan surface side at the front part in the direction of progress of the squeegee, wherein the pressure generating member forms a narrow path through which the viscous fluid flows between the pan surface and the pressure generating member, while the squeegee is moving.

In the viscous fluid transfer apparatus, the pressure generating member is provided in the vicinity of the tip on the pan surface side at the front part in the direction of progress of the leveling squeegee. Consequently, the narrow path is formed between the pressure generating member and the pan surface. Therefore, the viscous fluid flowing between the pressure generating member and the pan surface is maintained in a high pressure state. Consequently, even if a squeegee speed is high, the viscous fluid can be stably put on the pan surface in a predetermined thickness.

A tenth aspect of the invention is directed to the viscous fluid transfer apparatus, wherein a length of the stirring squeegee is equal to or greater than a scraping width of the leveling squeegee.

In the viscous fluid transfer apparatus, the stirring squeegee has a length which is equal to or greater than the scraping width of the leveling squeegee. Consequently, when the stirring squeegee is relatively moved over the transfer unit, a scraping track can be completely scraped by the leveling squeegee and the viscous fluid can be stirred without overflowing from the transfer unit.

An eleventh aspect of the invention is directed to the viscous fluid transfer apparatus, further including a stepped portion provided on the pan surface of the transfer unit at both ends in a direction of delivery of the leveling squeegee in a direction of the movement of the squeegee, wherein the stepped portion is protruded from the pan surface by a predetermined height to support both ends of the leveling squeegee in hanging down.

In the viscous fluid transfer apparatus, the stepped portion protruded from the pan surface of the transfer unit by a predetermined height is provided. Consequently, both ends of the leveling squeegee are supported in hanging down so that a clearance for the height of the stepped portion is generated together with the pan surface. Consequently, the viscous fluid having a desirable thickness can be put on the transfer unit by setting the height of the stepped portion to be a desirable height.

A twelfth aspect of the invention is directed to the viscous fluid transfer apparatus, further including a stepped portion provided on the pan surface side at both ends in the longitudinal direction of the leveling squeegee, wherein the stepped portion is protruded by a predetermined height.

In the viscous fluid transfer apparatus, the stepped portion protruded by a predetermined height is provided on both ends in the longitudinal direction of the leveling squeegee. Consequently, when the leveling squeegee is pushed against the transfer unit, the stepped portion on both ends of the squeegee contacts on the pan surface of the transfer unit so that a clearance for the height of the stepped portion is generated together with the pan surface in a region other than both ends of the squeegee. Therefore, the viscous fluid having a desirable thickness can be put on the transfer unit by setting the height of the stepped portion to be a desirable height.

A thirteenth aspect of the invention is directed to the viscous fluid transfer apparatus, wherein the squeegee driving mechanism includes a rocking arm having one of ends fixed to a rocking center shaft of the squeegee fixing member and the other end connected to a horizontal driving mechanism for rocking the squeegee fixing member, and an arm stopper for contacting on the rocking arm to control a rocking angle of the rocking arm.

In the viscous fluid transfer apparatus, the rocking arm has one of ends fixed to the rocking center shaft of the squeegee fixing member and the other end connected to a horizontal driving mechanism for rocking the squeegee fixing member. Consequently, the squeegee fixing member can be rocked around the rocking center shaft. Thus, the stirring squeegee and the leveling squeegee can be caused to alternately approach the transfer unit. Moreover, the arm stopper is provided to contact on the rocking arm at a predetermined rocking angle. Therefore, the rocking angle of the rocking arm can be controlled and the contact position of the arm stopper on the rocking arm can be regulated so that the heights of the squeegee and the transfer unit surface can be controlled finely.

A fourteenth aspect of the invention is directed to the viscous fluid transfer apparatus further including, a V block holding the squeegee fixing member on the end the of the squeegee fixing member, and a table having a projection and supporting the squeegee fixing member on the other end side of the squeegee fixing member by the projection, wherein the squeegee fixing member including a cylindrical pin in an axial direction to one of end side in a longitudinal direction of the squeegee fixing member, and an engagement portion having a key groove parallel with the axial direction is provided on the other end side of the squeegee fixing member, wherein the projection engaged with the key groove, and wherein the squeegee unit is supported removably by the V block, the table and the squeegee fixing member.

In the viscous fluid transfer apparatus, the squeegee fixing member has the pin connected to one of end sides in the longitudinal direction and the engagement portion having the key groove provided on the other end side. Consequently, the squeegee fixing member has one of the end sides thereof held by the V block and the other end supported on the formed table of the projection, thereby supporting the squeegee unit. Therefore, the squeegee unit can be removably supported and the squeegee fixing member can be prevented from being twisted, thereby enhancing the reproducibility of the attachment position. Accordingly, even if the squeegee unit is removed when cleaning the squeegee unit, it can be easily attached to an accurate position again so that maintenance can be enhanced.

A fifteenth aspect of the invention is directed to a viscous fluid transfer apparatus for forming a flat viscous fluid transfer surface for transferring a viscous fluid to a connecting terminal of an electronic component, including a belt conveyer having a planar belt surface on which the viscous fluid is to be put, a squeegee for uniformly flattening the viscous fluid put on the belt surface by a delivery operation of the belt conveyer, and a stirring mechanism provided in a front stage of the squeegee in a direction of delivery of the belt conveyer and serving to stir the viscous fluid on the belt surface.

In the viscous fluid transfer apparatus, after the viscous fluid put on the belt surface of the belt conveyer is stirred by the stirring mechanism, it is uniformly flattened over the belt surface through the squeegee with the delivery operation of the belt conveyer. Therefore, the viscous fluid transfer surface can be formed continuously. Consequently, a new viscous fluid transfer surface can always be exposed continuously.

A sixteenth aspect of the invention is directed to a viscous fluid transfer method of forming a flat viscous fluid transfer surface by a squeegee and immersing a terminal portion of an electronic component in the viscous fluid transfer surface, thereby transferring a viscous fluid to the electronic component, wherein the viscous fluid is put on a transfer unit having a flat pan surface, a plate-shaped stirring squeegee is relatively moved with respect to the pan surface in a forward direction, thereby stirring the viscous fluid, and a plate-shaped leveling squeegee is then moved relatively with respect to the pan surface in a reverse direction, thereby uniformly flattening the stirred viscous fluid on the transfer unit to form a viscous fluid transfer surface.

In the viscous fluid transfer method, the viscous fluid put on the transfer unit is stirred by relatively moving the stirring squeegee over the pan surface in a forward direction and the viscous fluid thus stirred is then flattened uniformly by relatively moving the leveling squeegee over the pan surface in a reverse direction, thereby forming a flat viscous fluid transfer surface, and the terminal portion of the electronic component is immersed in the viscous fluid transfer surface to transfer the viscous fluid to the electronic component. By relatively moving the two squeegees alternately, thus, the flat viscous fluid transfer surface can be formed stably and the viscous fluid can be uniformly transferred to the terminal portion of the electronic component.

A seventeenth aspect of the invention is directed to the viscous fluid transfer method, wherein when the leveling squeegee is relatively moved and the stirring squeegee is then moved relatively again in a forward direction, the viscous fluid overflowing from both ends in a longitudinal direction of the leveling squeegee during the relative movement of the leveling squeegee is scraped toward a central side in the longitudinal direction of the squeegee during the relative movement of the stirring squeegee.

In the viscous fluid transfer method, the viscous fluid overflowing from both ends in the longitudinal direction of the leveling squeegee is scraped toward the central side in the longitudinal direction of the squeegee during the relative movement of the stirring squeegee. Consequently, the viscous fluid can be prevented from overflowing from the transfer unit and the stirring squeegee and the leveling squeegee can be relatively moved continuously without causing the viscous fluid to overflow from the transfer unit.

An eighteenth aspect of the invention is directed to the viscous fluid transfer method, wherein a thickness of the viscous fluid transfer surface to be formed on the transfer unit is set by regulating a height of a rise from the pan surface of the transfer unit of the leveling squeegee.

In the viscous fluid transfer method, the thickness of the viscous fluid transfer surface to be formed on the transfer unit can be optionally set by regulating a rising height from the pan surface of the transfer unit of the leveling squeegee.

A nineteenth aspect of the invention is directed to the viscous fluid transfer method, wherein the height of the rise from the pan surface is regulated by causing the leveling squeegee to contact on the pan surface of the transfer unit over a whole width and setting a position of the contact to be a reference height.

In the viscous fluid transfer method, first of all, the leveling squeegee is caused to contact on the pan surface of the transfer unit over the whole width, thereby holding the leveling squeegee in parallel with the pan surface. Then, the position of the contact is set to be the reference height and the leveling squeegee is raised by a predetermined height from the reference height, thereby regulating the rising height from the pan surface. Consequently, the degree of parallelism of the leveling squeegee and the pan surface can be increased so that the rising height can be regulated with a high degree of parallelism maintained. Accordingly, the thickness of the viscous fluid transfer surface can be made uniform with high precision.

A twentieth aspect of the invention is directed to the viscous fluid transfer method, wherein the thickness of the viscous fluid transfer surface is set by a height of a stepped portion provided on the pan surface side on both ends in the longitudinal direction of the leveling squeegee.

In the viscous fluid transfer method, when the protrusion height of the stepped portion provided on both ends in the longitudinal direction of the leveling squeegee is set to be a predetermined height to cause the stepped portion of the leveling squeegee to contact on the pan surface of the transfer unit, the clearance generated between the leveling squeegee and the pan surface in a region other than both ends of the squeegee is set corresponding to the protrusion height of the stepped portion and the thickness of the formed viscous fluid transfer surface is set. Consequently, the thickness of the height of the stepped portion provided in the leveling squeegee is automatically set without requiring a regulating work.

A twenty-first aspect of the invention is directed to a viscous fluid transfer method of forming a flat viscous fluid transfer surface by a squeegee and immersing a terminal portion of an electronic component in the viscous fluid transfer surface, thereby transferring a viscous fluid to the electronic component, wherein the viscous fluid is stirred and put on a belt surface of a belt conveyer, and the viscous fluid put on the belt surface is uniformly flattened by a squeegee provided above the belt surface with a delivery operation of the belt conveyor, thereby forming the viscous fluid transfer surface.

In the viscous fluid transfer method, the viscous fluid is stirred and put on the belt surface of the belt conveyer and is uniformly flattened over the belt surface through the squeegee so that the viscous fluid transfer surface can be formed continuously. Consequently, a new viscous fluid transfer surface can always be exposed continuously.

A twenty-second aspect of the invention is directed to an electronic component mounting apparatus for sucking and holding an electronic component and mounting the electronic component into a predetermined mounting position, including an electronic component supply member for mounting a plurality of electronic components to supply a desirable one of the electronic components, a sucking nozzle for removably sucking and holding the electronic component, an attachment head for holding the sucking nozzle to rise and fall freely, a head moving portion for moving the attachment head in a horizontal plane, and the viscous fluid transfer apparatus according to any of claims 1 to 15 for uniformly flattening a viscous fluid on a transfer unit to form a flat viscous fluid transfer surface, wherein the electronic component sucked by the electronic component supply member is moved onto the transfer unit of the viscous fluid transfer apparatus and a terminal portion of the electronic component is immersed in the viscous fluid transfer surface by the up-down operation of the attachment head, thereby transferring the viscous fluid to the electronic component.

In the electronic component mounting apparatus, a desirable electronic component is sucked and held through the sucking nozzle from the electronic component supply member mounting a plurality of electronic components thereon, and is positioned on the transfer unit of the viscous fluid transfer apparatus by moving the attachment head through the head moving portion. Then, the attachment head is brought up and down to immerse the terminal portion of the electronic component in the viscous fluid transfer surface on the transfer unit, thereby transferring the viscous fluid to the electronic component. Consequently, the viscous fluid can be uniformly transferred to the electronic component and the electronic component to which the viscous fluid is transferred can be mounted in a predetermined position.

A twenty-third aspect of the invention is directed to the electronic component mounting apparatus, wherein the attachment head includes a rubber pad provided in a tip portion of the sucking nozzle and having a sucking surface which can be inclined freely and can be extended freely in a direction of suction, and a sucking attitude correcting member provided around the rubber pad in which a tip portion has a contact face to contact on a rear face of the electronic component during the suction of the electronic component.

In the electronic component mounting apparatus, the attachment head includes a rubber pad provided in the tip portion of the sucking nozzle and a sucking attitude correcting member provided around the rubber pad. Consequently, when the rubber pad is caused to contact on the rear face of the electronic component to suck the electronic component, the rubber pad is contracted in a sucking direction so that the rear face of the electronic component contacts on the tip portion of the sucking attitude correcting member. Consequently, the contact face of the tip portion of the sucking attitude correcting member is pushed against the rear face of the electronic component so that the sucking attitude of the electronic component is corrected. Then, in the case in which the sucking nozzle is pushed against the inclined surface with the electronic component sucked and a part of the electronic component is separated from the sucking attitude correcting member, the rubber pad is inclined along the inclined surface so that the suction of the electronic component is maintained and the electronic component is not removed from the sucking nozzle. Accordingly, the electronic component can be always sucked and maintained stably.

A twenty-fourth aspect of the invention is directed to the electronic component mounting apparatus, wherein the sucking attitude correcting member is constituted by a pair of rod bodies provided on both sides of the rubber pad.

In the electronic component mounting apparatus, the sucking attitude correcting member has such a structure that a pair of rod bodies are provided on both sides of the rubber pad. Consequently, the sucking attitude of the electronic component can be corrected with a simple structure.

A twenty-fifth aspect of the invention is directed to the electronic component mounting apparatus, wherein the contact face of the sucking attitude correcting member is formed to be inclined from a horizontal plane.

In the electronic component mounting apparatus, the contact face of the sucking attitude correcting member is formed to be inclined from the horizontal plane. Consequently, the electronic component can be inclined at an optional angle to be sucked and held into the sucking nozzle. For example, when the electronic component is to be pushed against the inclined surface or is to be sucked from the inclined surface, the contact face is previously inclined at the inclination angle so that the sucking state of the electronic component can be maintained stably.

A twenty-sixth aspect of the invention is directed to the electronic component mounting apparatus, further including a multi-head having a plurality of attachment heads arranged in parallel, the transfer unit of the viscous fluid transfer apparatus including a pan surface having a greater width than an attachment head arrangement width of the multi-head.

In the electronic component mounting apparatus, the transfer unit of the viscous fluid transfer apparatus includes a pan surface having a greater width than the attachment head arrangement width of the multi-head. Consequently, the electronic component sucked into the attachment head of the multi-head is simultaneously brought up and down by each attachment head so that the viscous fluid can be transferred at a time. Consequently, the efficiency of the transfer of the viscous fluid to the electronic component can be enhanced and a mounting speed can be increased.

A twenty-seventh aspect of the invention is directed to the electronic component mounting apparatus, wherein the transfer unit includes a pan surface having a greater width than a double of the attachment head arrangement width of the multi-head.

In the electronic component mounting apparatus, the transfer unit includes the pan surface having a greater width than a double of the attachment head arrangement width of the multi-head. Consequently, it is possible to obtain a sufficient space for simultaneously bringing each attachment head of the multi-head up and down plural times over the same viscous fluid transfer surface and it is not necessary to form the viscous fluid transfer surface again for each transfer operation. Consequently, the viscous fluid transfer efficiency can be enhanced and the mounting speed can be increased.

A twenty-eighth aspect of the invention is directed to an electronic component mounting method of mounting an electronic component in a predetermined mounting position, including the steps of sucking an electronic component by an attachment head having a sucking nozzle, while uniformly flattening a viscous fluid on a transfer unit having a planar pan surface to form a viscous fluid transfer surface, moving the sucked attachment head of the electronic component to an upper position of the viscous fluid transfer surface, bringing the sucking nozzle down until a terminal portion of the electronic component is immersed in the viscous fluid transfer surface, raising the sucking nozzle after transferring the viscous fluid to the electronic component and moving the attachment head to a predetermined mounting position, and bringing down the sucking nozzle in the mounting position, thereby mounting the electronic component.

In the electronic component mounting method, the electronic component is sucked into the sucking nozzle of the attachment head, while the viscous fluid is uniformly flattened over the transfer unit to form the viscous fluid transfer surface, thereby moving the sucked attachment head of the electronic component to the upper position of the viscous fluid transfer surface. Consequently, the transfer of the viscous fluid is completely prepared. Next, the sucking nozzle is brought down until the terminal portion of the electronic component is immersed in the viscous fluid transfer surface so that the viscous fluid is transferred to the terminal portion, and the sucking nozzle is then raised and the attachment head is moved to the predetermined mounting position. Consequently, the electronic component to which the viscous fluid is transferred is positioned in the upper part of the mounting position. The sucking nozzle is brought down, thereby mounting the electronic component having the terminal portion to which the viscous fluid is transferred.

A twenty-ninth aspect of the invention is directed to the electronic component mounting method, wherein the sucking nozzles of a multi-head having a plurality of attachment heads arranged in parallel are controlled to be brought up and down at the same time.

In the electronic component mounting method, each sucking nozzle of the multi-head having a plurality of attachment heads arranged in parallel is controlled to carry out the up-down operation at the same time. For example, consequently, in the case in which the same kind of electronic components are sucked into each sucking nozzle, the viscous fluid can be transferred at the same time so that the transfer efficiency can be enhanced and the mounting speed can be increased.

A thirtieth aspect of the invention is directed to the electronic component mounting method, wherein a height of the viscous fluid transfer surface of the transfer unit is detected before the viscous fluid is transferred to the electronic component, and an amount of fall of the sucking nozzle of the attachment head is set according to the height thus detected.

In the electronic component mounting method, the height of the viscous fluid transfer surface of the transfer unit is detected before the viscous fluid is transferred to the electronic component so that the amount of fall of the sucking nozzle required before the electronic component comes in contact with the viscous fluid transfer surface is obtained with high precision. Accordingly, the height of the electronic component from the viscous fluid transfer surface can be set with high precision and the viscous fluid can be immersed in the electronic component in a desirable thickness.

A thirty-first aspect of the invention is directed to the electronic component mounting method, wherein the viscous fluid transfer surface having a predetermined thickness is formed on the transfer unit and the terminal portion of the electronic component is pushed to contact on the pan surface of the transfer unit, thereby transferring the viscous fluid having the predetermined thickness to the electronic component.

In the electronic component mounting method, the terminal portion of the electronic component is pushed against the viscous fluid transfer surface formed on the transfer unit in a predetermined thickness to contact on the pan surface. Consequently, the viscous fluid for the height of the viscous fluid transfer surface is transferred from the pan surface to the terminal portion of the electronic component. Accordingly, when the viscous fluid having a thickness suitable for the electronic component is formed on the transfer unit, the viscous fluid can be easily transferred in a proper thickness to the electronic component by a simple push operation without setting the amount of movement of the sucking nozzle with high precision.

A thirty-second aspect of the invention is directed to the electronic component mounting method, wherein the electronic component to which the viscous fluid is transferred is stacked and mounted on a rear face opposite to a mounting surface side of the electronic component which has already been mounted on a circuit board.

In the electronic component mounting method, the electronic component to which the viscous fluid is transferred is stacked and mounted on the rear face opposite to the mounting surface side of the electronic component which has already been mounted on a circuit board. Consequently, the electronic component can be stacked and mounted in the same space in the plane of the circuit board so that the mounting density of the circuit board can be enhanced.

A thirty-third aspect of the invention is directed to the electronic component mounting method, wherein a reference mark for alignment provided on the rear face of the mounted electronic component is detected and a mounting position of the electronic component to be stacked and mounted on the rear face is corrected by setting the detected reference mark as a reference.

In the electronic component mounting method, the reference mark for alignment provided on the rear face of the mounted electronic component is detected and the mounting position or mounting angle of the electronic component is detected. By setting the detected reference mark as a reference to correct the mounting position of the electronic component to be mounted on the rear face, the electronic component can be mounted on the rear face of the mounted electronic component by canceling a shift in the mounting position. Accordingly, the electronic component to be mounted on the rear face of the mounted electronic component can be aligned and stacked with high precision for the mounted electronic component.

A thirty-fourth aspect of the invention is directed to a semiconductor device having a plurality of solder balls arranged as connecting terminals on a mounting surface side, wherein a land for terminal connection is provided in a position corresponding to the connecting terminal of the semiconductor device on a rear face opposite to the mounting surface side.

In the semiconductor device, the land for terminal connection is provided in the position corresponding to the connecting terminal of the semiconductor device on the rear face of the semiconductor device. Consequently, the land of the semiconductor device on the lower stage side and the connecting terminal of the semiconductor device on the upper stage side are connected to each other when the semiconductor device is stacked. Thus, the semiconductor device can be simplified and can be constituted as a stacked structure.

A thirty-fifth aspect of the invention is directed to the semiconductor device, wherein the connecting terminal of the semiconductor device has a solder fixed to a heat-resistant pin.

In the semiconductor device, even if the length of the pin is not equal, the solder absorbs the shortage of the length thereof and is reliably connected to the land. By setting the lower end of the pin to be a plane, moreover, the attitude of the electronic component can be stably fixed without an inclination from the circuit board surface. Even if the solder is exposed to a high temperature in a reflow process carried out again, furthermore, it is maintained to stick around the pin by a surface tension. Therefore, electrodes can be prevented from being short-circuited.

A thirty-sixth aspect of the invention is directed to the semiconductor device, wherein a reference mark for alignment is provided on the rear face opposite to the mounting surface side.

In the semiconductor device, when the semiconductor device is to be stacked and mounted, the connecting terminal of the semiconductor device on the upper stage side can be aligned with the land of the semiconductor device on the lower stage side with high precision. Even if the semiconductor device on the lower stage side is shifted from a predetermined position, the amount of the shift can be cancelled and the semiconductor device can be stacked.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an electronic component mounting apparatus including a viscous fluid transfer apparatus according to the invention.

FIG. 2 is an enlarged perspective view showing the transfer head of the electronic component mounting apparatus.

FIG. 3 is a schematic plan view for illustrating the operation of the electronic component mounting apparatus.

FIGS. 4(a), (b), and (c) are views showing a three-dimensional mounting method for mounting an electronic component in a multi-stage.

FIG. 5 is a perspective view showing the schematic structure of a solder cream transfer apparatus attached to the electronic component mounting apparatus and serving to transfer a solder cream to the electronic component.

FIG. 6 is a side view showing the solder cream transfer apparatus, a part of which is taken away.

FIG. 7 is an enlarged view showing the positional relationship between an arm for controlling the rocking motion of a rocking arm, a stirring squeegee and a leveling squeegee, and an arm stopper.

FIG. 8 is a view seen in the direction of an arrow A of FIG. 7.

FIG. 9 is a top view showing a squeegee unit.

FIG. 10 is a side view showing the solder cream transfer apparatus seen from the side of attachment to the electronic component mounting apparatus.

FIG. 11 is a side view showing the squeegee unit.

FIG. 12(a) is an exploded view showing the support structure of a buried pin seen in a direction of B in FIG. 10 and FIG. 12(b) is a view seen in the direction of B in an assembly state thereof.

FIG. 13(a) is an exploded view showing the support structure of an engagement portion seen in a section taken along C--C in FIG. 10 and FIG. 13(b) is a sectional view taken along C--C in an assembly state thereof.

FIGS. 14(a) and (b) are views in which the lengths of the stirring squeegee and the leveling squeegee are compared with each other.

FIGS. 15(a) and (b) are views showing the shape of the leveling squeegee, FIG. 15(a) being a front view and FIG. 15(b) being a sectional view taken along D--D.

FIG. 16 is a view showing the state of scrape of the leveling squeegee.

FIGS. 17(a) and (b) are views showing the shape of the stirring squeegee, FIG. 17(a) being a front view and FIG. 17(b) being a bottom view.

FIG. 18 is a sectional view taken along E--E in FIG. 17.

FIG. 19 is an enlarged perspective view showing both ends on the solder cream press side of the stirring squeegee.

FIG. 20 is a view illustrating the flow of a solder cream with a squeegee movement.

FIGS. 21(a), (b), and (c) are views illustrating the operation of the solder cream transfer apparatus on a stepwise basis.

FIGS. 22(a), (b), and (c) are views illustrating the operation of the solder cream transfer apparatus on a stepwise basis.

FIGS. 23(a), (b), (c) and (d) are views illustrating, on a stepwise basis, a state in which the transfer surface of the solder cream is formed by using the solder cream transfer apparatus.

FIGS. 24(a) and (b) are views showing the structure of a sucking nozzle, FIG. 24(a) being a front view and FIG. 24(b) being a side view, a part of which is taken away.

FIGS. 25(a), (b), and (c) are views showing a state in which the solder cream is transferred to the electronic component over the pan surface of a transfer unit inclined from a horizontal plane.

FIGS. 26(a), (b), and (c) are views showing a state in which the electronic component mounted on the surface inclined from the horizontal plane is sucked.

FIG. 27 is a view showing a state in which a space between the tip portions of a sucking component correcting member is enlarged.

FIGS. 28(a), (b), and (c) are views showing a state in which the solder cream on the pan surface of the transfer unit of the solder cream transfer apparatus is transferred to the electronic component by using the sucking nozzle.

FIG. 29 is an enlarged view showing a solder ball obtained after the transfer of the solder cream.

FIG. 30 is a view showing the push-in depth of the solder ball.

FIGS. 31(a) and (b) are views showing a state in which a transfer operation is carried out over the same solder cream transfer surface plural times.

FIGS. 32(a) and (b) is a view showing another state in which a transfer operation is carried out over the same solder cream transfer surface plural times.

FIG. 33 is a view showing a state in which the transfer operation shown in FIG. 31 and the transfer operation shown in FIG. 32 are combined to carry out a transfer