Title: Electronic assembly having a more dense arrangement of contacts that allows for routing of traces to the contacts
Abstract: An electronic assembly is described, having a substrate and contacts on the substrate which are spaced and arranged in a manner that allows for a more dense arrangement of contacts but still allows for routing of traces between the contacts.
Patent Number: 6,885,102 Issued on 04/26/2005 to Singh, et al.
| Inventors:
|
Singh; Kuljeet (Folsom, CA);
Wells; Kevin E. (El Dorado Hills, CA);
Delino; Julius (El Dorado Hills, CA)
|
| Assignee:
|
Intel Corporation (Santa Clara, CA)
|
| Appl. No.:
|
228524 |
| Filed:
|
August 26, 2002 |
| Current U.S. Class: |
257/738; 257/734; 257/737; 257/691; 257/774; 257/773; 257/778; 257/698; 174/260 |
| Intern'l Class: |
H05K 001//16 |
| Field of Search: |
257/773,737,738,734,778,782,698,692,693,691,784,786
174/260
|
References Cited [Referenced By]
U.S. Patent Documents
| 5512765 | Apr., 1996 | Gaverick.
| |
| 5691569 | Nov., 1997 | Palmer.
| |
| 5783870 | Jul., 1998 | Mostafazadeh et al.
| |
| 5784262 | Jul., 1998 | Sherman.
| |
| 6064113 | May., 2000 | Kirkman.
| |
| 6376769 | Apr., 2002 | Chung.
| |
| 6417463 | Jul., 2002 | Cornelius et al.
| |
| 2001/0035576 | Nov., 2001 | Wachtler et al.
| |
| 2002/0060318 | May., 2002 | Katz.
| |
| 2003/0170444 | Sep., 2003 | Stewart et al.
| |
| 2003/0021122 | Oct., 2003 | Hsu et al.
| |
Primary Examiner: Williams; Alexander Oscar
Attorney, Agent or Firm: Blakely, Sokoloff, Taylor & Zafman LLP
Claims
1. An electronic assembly comprising:
a substrate;
first to fourth functional contacts on the substrate, with center points on tips
of corners of a first area having a substantially rectangular shape, an entire
region within and excluding sides of the rectangular shape being otherwise void
of center points of functional contacts; and
a fifth functional contact on the substrate, with a center point within and spaced
from all sides of a second area having the same shape, dimensions, and orientations
as, and sharing one side with the first area.
2. The electronic assembly of claim 1, wherein the first area is void of any
portions of any contacts except for portions of the first to fourth contacts.
3. The electronic assembly of claim 1, further comprising:
at least a sixth functional contact on the substrate next to the first contact,
center points of the second and sixth contacts being the same distance from the
center point of the first contact.
4. The electronic assembly of claim 1, further comprising:
sixth through eighth functional contacts on the substrate in a row forming an
edge of a third area having the same shape, dimensions, and orientation as, and
sharing one side with the first area.
5. The electronic assembly of claim 4, wherein the first area is between the
second and third areas.
6. The electronic assembly of claim 1, further comprising:
sixth through ninth functional contacts on the substrate, with center points
on tips of corners of a third area having a substantially rectangular shape, an
entire region within and excluding sides of the rectangular shape of the third
area being otherwise void of center points of functional contacts; and
a tenth functional contact on the substrate, with a center point spaced from
all sides within a fourth area having the same shape, dimensions, and orientation
as, and sharing one side with the third area.
7. The electronic assembly of claim 6, wherein the first, second, eighth, and
ninth contacts are in the same row.
8. The electronic assembly of claim 6, wherein the second and fourth areas are
between the first and third areas.
9. The electronic assembly of claim 1, wherein the substrate is a package substrate,
further comprising:
a microelectronic die mounted to the package substrate on a side of the package
substrate opposing the contacts.
10. The electronic assembly of claim 9, further comprising:
a carrier substrate having terminals matching and contacting the contacts.
11. An electronic assembly, comprising:
a substrate; and
five functional contacts on the substrate with center points at tips of corners
of a first pentagonal shape, an entire region within and excluding sides of the
first pentagonal shape being otherwise void of center points of functional contacts,
three of the corners sequentially after one another being obtuse.
12. The electronic assembly of claim 11, wherein a fourth of the corners is 90°.
13. The electronic assembly of claim 12, wherein a fifth of the corners is 90°.
14. The electronic assembly of claim 12, further comprising:
five functional contacts on the substrate at tips of corners of a second pentagonal
shape, an entire region within and excluding sides of the second pentagonal shape
being otherwise void of center points of functional contacts, three of the corners
of the second pentagonal shape sequentially after one another being obtuse.
15. The electronic assembly of claim 12, wherein a second of the three corners
of the first pentagonal shape and a second of the three corners of the second pentagonal
shape point toward one another.
16. The electronic assembly of claim 14, wherein two of the contacts of the first
pentagonal shape are in the same row as two of the contacts of the second pentagonal shape.
17. An electronic assembly, comprising:
a substrate;
first and second functional contacts with center points in a first row;
third and fourth contacts with center points in a second row next to the first
row and spaced by a first distance from the first row, the center points of the
first and third contacts being in a first column and the center points of the second
and fourth contacts being in a second column, an entire area within and excluding
lines connecting center points of the first, second, third, and fourth contacts
being void of center points of functional contacts; and
a fifth functional contact in an extension of a corridor between the first and
second columns, on a side of the second row opposing the first row and having a
center point spaced from the second row by a second distance that is less than
the first distance.
18. The electronic assembly of claim 17, further comprising:
sixth and seventh functional contacts, center points of the third, fourth, sixth
and seventh contacts being at corners of a rectangular shape, with the fifth contact
within the rectangular shape.
19. The electronic assembly of claim 18, wherein a spacing between the center
points of the third and sixth contacts is between one and two times a spacing between
the first and third contacts.
Description
BACKGROUND OF THE INVENTION
1). Field of the Invention
This invention relates to an electronic assembly, and more particularly to a
more dense arrangement of contacts on a substrate of the electronic assembly that
still allows for routing of traces to the contacts without the need for expensive/non-standard
manufacturing processes or technologies.
2). Discussion of Related Art
Microelectronic dies are usually mounted to package substrates, primarily
to provide structural support to the microelectronic dies. Tiny balls are first
secured to a surface of the package substrate opposing a side thereof to which
the microelectronic die is secured. The balls provide functionality to a circuit
in the microelectronic die by providing an electric path through which signals
can be transmitted through the package substrate to or from the circuit, or for
providing power or ground to the circuit.
The balls are subsequently located against corresponding terminals on a carrier
substrate such as a motherboard, and secured to the terminals in a thermal reflow
process. Electric signals can then be transmitted through traces in and on surfaces
of the carrier substrate through the reflowed balls to or from the circuit.
The balls are usually located in a grid of rows and columns, also referred to
as a "ball grid array," abbreviated as "BGA." A BGA package does not allow for
a high density of balls while still allowing for routing of traces between outer
ones of the balls to inner ones of the balls.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described by way of example with reference to the accompanying
drawings, wherein:
FIG. 1 is a side view of a selection of contacts on a surface of a package substrate
when held in a vertical plane;
FIG. 2 is a side view of the package substrate, illustrating the selection of
contacts of FIG. 1 and other contacts on the package substrate; and
FIG. 3 is a side view after the package substrate is rotated so as to be in
a horizontal plane and an electronic assembly is assembled from the package substrate,
the contacts thereon, a microelectronic die, and a carrier substrate.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 of the accompanying drawings illustrates a selection
10 of functional
contacts A through AC that are placed on a portion of a package substrate
12.
The distances of the functional contacts from a horizontal line through a center
of the substrate
12 are given down the left of the figure, and their distances
from a vertical axis are given at the bottom.
The contacts B through AC are located in three columns. The first column, which
includes contacts B, E, H, K, N, Q, S, V, Y, and AA have center points in a column
through a center of the package substrate
12. The contacts C, F, I, L, O,
U, and AB have center points in a column that is 1.092 mm from the column containing
contact B. The contacts D, G, J, M, P, R, T, W, Z, and AC are in a column that
is 2.184 mm from the column containing contact B, and therefore 1.092 mm from the
column containing contact C. The contact A is at a distance of 1.981 mm from the
column containing contact B.
The contacts B, C, and D have center points that are in a row that is 16.967
mm from the center point of the package substrate
12. The contacts E through
P are in similar rows, each row containing three of the contacts and spaced from
a previous row by a distance of 1.016 mm. The contacts B through P are thus in
a rectangular grid with columns that are spaced from one another by 1.092 mm, and
rows that spaced from one another by 1.016 mm. The contact A is at a distance that
is 1.016 mm above the row containing contact B.
The contacts Q and R have center points that are in a row that is 1.016 mm below
the row containing contact N, and the contacts S and T have center points that
are in a row that is spaced by a distance of 1.016 mm from the row containing contact
Q. An area is identifiable having a rectangular shape with the contacts Q, S, T,
and R on tips of corners of the rectangular shape. The rectangular shape has a
width of 2.184 mm and a height of 1.016 mm. The only ones of the contacts that
are within the rectangular area are quarters of the contacts Q, S, T, and R. The
rectangular area is thus otherwise void of any functional contacts.
The contact U is at a distance of 0.736 mm below the row containing contact S.
An imaginary area can be identified by connecting the center point of contact S
with reference numeral
14, reference numeral
14 with reference numeral
16, reference numeral
16 with a center point of the contact T, and
the center point of the contact T with the center point of the contact S. Such
an imaginary area has the same shape, dimensions, and orientation as the rectangular
shape defined by center points of the contacts Q, S, T, and R. The imaginary shape
thus also has a width of 2.184 mm and a height of 1.016 mm. The imaginary shape
also shares one side, namely the side connecting center points of the contacts
S and T, with the rectangular shape of the area defined by center points of the
contacts Q, S, T, and R. The center point of the contact U is entirely within the
imaginary area, and is spaced from all four sides of the imaginary area. It could
also be noted that a corridor is identifiable between one column containing contacts
Q and S and another column containing contacts R and T, with contact U in an extension
of the corridor. What can thus be noted is that a pentagonal shape is identifiable
by connecting the center points of the contacts Q, S, U, T, and R. The pentagonal
shape is entirely void of any other contacts. The corner of the pentagonal shape
defined by connecting the center points of the contacts Q, S, and U is obtuse,
as are the corners defined by connecting the center points of the contacts S, U,
and T, and by connecting the center points of the contacts U, T, and R, respectively.
The corner identifiable by connecting center points of the contacts R, Q, and S
is 90°, as is the corner identifiable by connecting center points of the contacts
T, R, and Q. A similar pentagonal shape with longer sides is identifiable by connecting
center points of the contacts N, Q, S, U, T, R, P, and O, all of which having center
points that are on corners or sides of the pentagonal shape as opposed to within
the pentagonal shape.
An area having a pentagonal shape is also identifiable by connecting center points
of the contacts AA, AB, AC, Z, X, and Y. A corner identifiable by connecting center
points of the contacts Y, X, and Z is more obtuse than the corner identifiable
by connecting center points of the contacts S, U, and T. The corner defined by
center points of contacts Y, X, and Z points toward the corner identifiable by
the center points of the contacts S, U, and T. Other aspects of the pentagonal
shapes formed by center points of the contacts Q, S, U, T, and R, and center points
of the contacts AA, AB, AC, Z, X, and Y are the same. The contacts AA, AB, AC,
Z, and Y are on a grid with rows and columns that are spaced from one another by
distances that are the same as spaces between rows and columns of a grid on which
the contacts B through T are located.
The selection
10 is also illustrated on FIG.
2. The contacts in
the first two columns of the selection
10 are repeated along all four outer
edges of the package substrate
12.
The contacts B through P are in rows extending parallel to a top edge
20A
of the package substrate
12, each row being spaced by a distance of 1.016
mm from a previous row. The row containing contact S has ten of the contacts. The
other rows containing the contacts B through R each have more than ten contacts.
The row containing the contact B, for example, has 31 contacts.
The contacts U through AC are also located in rows extending parallel to the
upper edge
20A. The contacts A through P are located in an outer region,
whereas the contacts U through AC are located in an intermediate region between
the outer region and an inner region of the package substrate
12. The spacings
between the rows containing the contacts S, U, V, X, and Y, respectively, are less
than the spacings between the rows containing the contacts P through T.
More contacts AD are formed on the inner region of the package substrate
12.
The contacts AD have center points that are in rows and columns on the same grid
as the contacts on the outer region, namely the contacts B through T. A region
between the contacts AD and the row containing the contact AA is free of contacts,
and has a width that is approximately five times a spacing between rows of the
contacts AD.
FIG. 3 illustrates a complete electronic assembly
30 that includes the
package substrate
12. The contacts hereinbefore described are, in the embodiment
illustrated in FIG. 3, in fact tiny balls
32 that are secured to the package
substrate
12. The electronic assembly
30 further includes a microelectronic
die, typically a semiconductor die
34, mounted on a surface of the package
substrate
12 opposing the balls
32. An integrated circuit in the
semiconductor die
34 is electrically connected through vias (not shown)
in the package substrate
12 to the balls
32.
The electronic assembly
30 further includes a carrier substrate in the
form of a motherboard
36 and a plurality of terminals
38 on the motherboard
36. A layout of the terminals
38 is a mirror image of the layout
of the balls
32 as illustrated in FIG.
2. Each one of the balls
32
thus contacts a respective one of the terminals
38. The electronic assembly
30 is inserted into a reflow oven which melts the balls
32. The electronic
assembly
30 is subsequently allowed to cool, whereafter the balls
32
secure the package substrate
12 to the terminals
38.
The layout illustrated in FIGS. 1 and 2 allows for a more dense layout of the
contacts while still allowing for traces to be routed on upper and lower surfaces
of the motherboard
36 to the terminals
38. Exactly three traces can
be routed between, for example, the contacts B and C because of the pitch of 1.092
mm between the contacts B and C. Although even a slight decrease to a pitch of,
for example, to 1.08 mm will disallow routing of three traces, it is within the
scope of the invention that the pitch between the columns may be between 1.05 and
1.15 mm. It is also within the scope of the invention that the pitches between
the rows containing the contacts A through P are between 1.05 and 1.15 mm. Existing
pitches, by contrast, are either 1 mm or 1.20 mm.
While certain exemplary embodiments have been described and shown in the accompanying
drawings, it is to be understood that such embodiments are merely illustrative
and not restrictive of the current invention, and that this invention is not restricted
to the specific constructions and arrangements shown and described since modifications
may occur to those ordinarily skilled in the art.
*
