U.S. patent application number 11/697958 was filed with the patent office on 2007-08-02 for ball grid array connector.
This patent application is currently assigned to FCI Americas Technology Inc.. Invention is credited to Donald K. JR. Harper, Steven E. Minich.
Application Number | 20070178736 11/697958 |
Document ID | / |
Family ID | 36034651 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070178736 |
Kind Code |
A1 |
Minich; Steven E. ; et
al. |
August 2, 2007 |
Ball Grid Array Connector
Abstract
An electrical connector having an electrical contact with a
terminal portion and a contact receiving wafer is disclosed. The
connector may also include a contact receiving wafer having a face
that at least partially defines an aperture that extends
therethrough. A terminal portion of the contact may extend at least
partially into the aperture. The faces that define the aperture
allow the terminal portion of the contact to move in each of a
plurality of directions, while also containing the terminal portion
of the contact in each direction. The terminal portion of the
contact may have connected a solder ball. The solder ball may
define a diameter that is larger than the width of the aperture
restricting movement of the wafer along a length of the
contact.
Inventors: |
Minich; Steven E.; (York,
PA) ; Harper; Donald K. JR.; (Camp Hill, PA) |
Correspondence
Address: |
WOODCOCK WASHBURN, LLP
CIRA CENTRE, 12TH FLOOR
2929 ARCH STREET
PHILADELPHIA
PA
19104-2891
US
|
Assignee: |
FCI Americas Technology
Inc.
Reno
NV
|
Family ID: |
36034651 |
Appl. No.: |
11/697958 |
Filed: |
April 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10940433 |
Sep 14, 2004 |
7214104 |
|
|
11697958 |
Apr 9, 2007 |
|
|
|
Current U.S.
Class: |
439/179 |
Current CPC
Class: |
H05K 7/1084 20130101;
H01R 13/6315 20130101; H01R 12/7076 20130101; H01R 43/24 20130101;
H01R 13/24 20130101; H01R 12/707 20130101; H01R 13/514
20130101 |
Class at
Publication: |
439/179 |
International
Class: |
H01R 3/08 20060101
H01R003/08 |
Claims
1. An electrical connector comprising: an electrical contact having
a terminal portion; a leadframe housing through which the contact
at least partially extends; and a contact receiving wafer having a
face that at least partially defines an aperture that extends
through the wafer, wherein the wafer abuts the leadframe housing
and is adapted to remain part of the connector when the electrical
contact is electrically connected to an electrical device, and
wherein the terminal portion of the contact extends at least
partially into the aperture, the aperture allows the terminal
portion of the contact to move in a first direction without
abutting the face, and the face contains the terminal portion of
the contact in the first direction.
2. The electrical connector of claim 1, wherein the aperture allows
the terminal portion of the contact to move in a second direction,
and the wafer has a second face that at least partially defines the
aperture and contains the terminal portion of the contact in the
second direction.
3. The electrical connector of claim 2, wherein the second
direction is orthogonal to the first direction.
4. The electrical connector of claim 1, further comprising a solder
ball connected to the terminal portion of the contact.
5. The electrical connector of claim 4, wherein the solder ball
restricts movement of the wafer along a length of the contact.
6. The electrical connector of claim 4, wherein the solder ball
restricts movement of the contact into the aperture.
7. The electrical connector of claim 4, wherein the wafer is
contained between the solder ball and the lead frame.
8. The electrical connector of claim 4, wherein the aperture has a
width and the solder ball has a diameter that is larger than the
width of the aperture.
9. A contact receiving wafer for an electrical connector, the
electrical connector comprising a leadframe housing through which
an electrical contact at least partially extends, the contact
receiving wafer comprising: a substrate having a plurality of
apertures extending therethrough, wherein each said aperture is at
least partially defined by a respective face and is adapted to
receive in a first direction a respective terminal portion of the
respective electrical contact, and wherein each said aperture
allows the respective terminal portion of the respective electrical
contact to move in a second direction perpendicular to the first
direction without abutting the face that defines the aperture after
the electrical connector is attached to a second electrical
connector, and wherein each face contains the terminal portion of
the respective electrical contact received therein in the second
direction, wherein the substrate is configured to abut the
leadframe housing.
10. An electrical connector comprising: an electrical contact
having a terminal portion; a leadframe housing through which the
contact at least partially extends; a contact receiving wafer
having a face that at least partially defines an aperture that
extends through the wafer, wherein the contact receiving wafer
abuts the leadframe; and a solder ball connected to the terminal
portion of the contact, wherein the terminal portion of the contact
extends at least partially into the aperture, the aperture allows
the terminal portion of the contact to move in a first direction
without abutting the face, and the face contains the terminal
portion of the contact in the first direction.
11. The electrical connector of claim 10, wherein the aperture
allows the terminal portion of the contact to move in a second
direction, and the contact receiving wafer has a second face that
at least partially defines the aperture and the second face
contains the terminal portion of the contact in the second
direction.
12. The electrical connector of claim 11, wherein the second
direction is orthogonal to the first direction.
13. The electrical connector of claim 10, wherein the solder ball
restricts movement of the wafer along a length of the contact.
14. The electrical connector of claim 10, wherein the solder ball
restricts movement of the contact into the aperture.
15. The electrical connector of claim 10, wherein the wafer is
contained between the solder ball and the lead frame.
16. The electrical connector of claim 10, wherein the aperture has
a width and the solder ball has a diameter that is larger than the
width of the aperture.
17. The contact receiving wafer of claim 9 wherein each said
aperture is square.
18. The contact receiving wafer of claim 11 wherein each said
aperture has the dimensions of about 0.6 mm by 0.6 mm.
19. The electrical connector of claim 12, further comprising a
connector housing, the connector housing having a post adapted to
be received in an orifice defined by a circuit board.
20. The electrical connector of claim 19, wherein the post
comprises a solderable surface.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/940,433, filed Sep. 14, 2004, the entirety
of which is incorporated herein by reference.
[0002] The subject matter disclosed and claimed herein is related
to the subject matter disclosed and claimed in co-pending U.S.
patent application Ser. No. 10/294,966, filed Nov. 14, 2002, which
is a continuation-in-part of U.S. patent application Ser. No.
09/990,794, filed Nov. 14, 2001, now U.S. Pat. No. 6,692,272, and
Ser. No. 10/155,786, filed May 24, 2002, now U.S. Pat. No.
6,652,318.
[0003] The subject matter disclosed and claimed herein is related
to the subject matter disclosed and claimed in U.S. patent
applications Ser. No. 10/940,329, filed Sep. 14, 2006, and Ser. No.
10/634,547, filed Aug. 5, 2003. The contents of each of the
above-referenced U.S. patents and patent applications is herein
incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0004] Generally, the invention relates to electrical connectors.
More particularly, the invention relates to ball grid array ("BGA")
connectors that allow for relative movement between the connector
housing and leadframe assemblies contained within the housing, even
after the connector is connected to a substrate such as a printed
circuit board.
BACKGROUND OF THE INVENTION
[0005] Printed circuit boards ("PCBs") are commonly used to mount
electronic components and to provide electrical interconnections
between those components and components external to the PCB. One
problem with conventional PCBs is flexing. PCBs flex under the
weight of attached electrical components when subject to
vibrations, assembly, and handling loads. Ultimately, the PCB with
attached electrical components are assembled in a chassis, such as
in a computer system. Handling and transit of the chassis assembly
can cause PCB flexing under the weight of the components.
[0006] Additionally, electrical components are becoming
increasingly heavy. Electrical components that are attached to the
PCB include, among others, the heat sink and fan assembly which is
attached to the central processing unit (CPU). These assemblies
often are upwards of a pound or more in weight, putting an
increased burden on the PCB.
[0007] In an effort to increase electrical component density on the
PCB, electrical components may be attached to the PCB using BGA
technology. A BGA microprocessor, for example, makes its electrical
connection via a solder ball on each connector of the BGA of the
electrical microprocessor and the electrical contacts on the
surface of the PCB. BGA components require a rigid substrate to
which they are attached. In effect, these BGA components are
soldered directly to the circuit board without intervening contacts
or wires. BGA components commonly incorporate tens or hundreds of
solder connections between the ball-grid package and the circuit
board. Any appreciable circuit board flexing may cause the solder
connections to shear, compress, fatigue, and subsequently
break.
[0008] There is a significant need in the art to provide a BGA
connector that has the ability to flex under various loads to
minimize stresses imposed on the solder ball connections.
SUMMARY OF THE INVENTION
[0009] An electrical connector may include an electrical contact
with a terminal portion and a contact receiving wafer. The contact
receiving wafer may have a face that at least partially defines an
aperture that extends through the wafer. The terminal portion of
the electrical contact may extend at least partially into the
aperture. The aperture may allow the terminal portion of the
contact to move in a first direction. The face of the wafer may
contain the terminal portion in the first direction.
[0010] The electrical connector may include a solder ball connected
to the terminal portion of the contact. The solder ball may have a
diameter that is larger than the width of the aperture. Thus, the
solder ball may restrict movement of the wafer along a length of
the contact.
[0011] The electrical connector may also include a leadframe. The
electrical contact may at least partially extend through the
leadframe. The wafer may be contained between the solder ball and
the leadframe.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIGS. 1A and 1B depict an example embodiment of a connector
according to the invention.
[0013] FIG. 2 depicts an example embodiment of an insert molded
leadframe assembly according to the invention.
[0014] FIG. 3 provides a partial view of an example embodiment of a
ball grid array connector according to the invention, without a
wafer or solder balls.
[0015] FIG. 4 provides a partial view of an example embodiment of a
ball grid array connector according to the invention, without
solder balls.
[0016] FIG. 5 provides a partial view of a ball grid array formed
on a plurality of electrical contacts, without a wafer.
[0017] FIG. 6 provides a perspective bottom view of a connector
according to the invention with solder posts attached to a
housing.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0018] FIGS. 1A and 1B depict an example embodiment of a ball grid
array ("BGA") connector 100 according to the invention having a
ball grid side 100A (best seen in FIG. 1A) and a receptacle side
100B (best seen in FIG. 1B). Though the connector described herein
is depicted as a ball grid array connector, it should be understood
that through pin mounting or surface mounting other than BGA may
also be used. As shown, the BGA connector 100 may include a housing
101, which may be made of an electrically insulating material, such
as a plastic, for example, that defines an internal cavity. The
housing 101 may contain one or more insert molded leadframe
assemblies ("IMLAs") 115. In an example embodiment, the housing 101
may contain ten IMLAs 115, though it should be understood that the
housing 101 may contain any number of IMLAs 115.
[0019] FIG. 2 depicts an example embodiment of an IMLA 115. As
shown, the IMLA 115 may include a set of one or more electrically
conductive contacts 211 that extend through an overmolded housing
215. The overmolded housing 215 may be made of an electrically
insulating material, such as a plastic, for example. Adjacent
contacts 211 that form a differential signal pair may jog toward or
away from each other as they extend through the overmolded housing
215 in order to maintain a substantially constant differential
impedance profile between the contacts that form the pair. For
arrangement into columns, the contacts 211 may be disposed along a
length of the overmolded housing 215 (e.g., along the "Y" direction
as shown in FIG. 2).
[0020] The contacts 211 may be dual beam receptacle contacts, for
example. Such a dual beam receptacle contact may be adapted to
receive a complementary beam contact during mating with an
electrical device. As shown in FIG. 2, each contact 211 may have a
dual beam receptacle portion 217 and a terminal portion 216. The
terminal portion 216 may be adapted to receive a solder ball 120 as
described below.
[0021] An IMLA 115 may also include one or more containment tabs
204. In an example embodiment, a respective tab 204 may be disposed
on each end of the IMLA 115. For example, the contact 211 at the
end of the IMLA 115 may have a tab 204 that extends beyond a face
of the overmolded housing 215. In such an embodiment, the tab 204
may be made of the same material as the contact 211 (e.g.,
electrically conductive material). Alternatively, the tabs 204 may
extend from the overmolded housing 215, and may be attached to the
overmolded housing 215 or integrally formed with the overmolded
housing 215. In such an embodiment, the tab 204 may be made of the
same material as the overmolded housing 215 (e.g., electrically
insulating material).
[0022] As best seen in FIG. 3, the connector housing 101 may
include one or more tab receptacles 302. In an example embodiment,
a respective pair of tab receptacles 302 are arranged on opposite
sides of the housing 101 to contain an associated IMLA 115 in a
first direction (such as the Y-direction shown in FIG. 3). Each tab
receptacle 302 may have an opening 322 for receiving a respective
tab 204. Each such opening may be defined by a plurality of faces
332 formed within the tab receptacle. The tab receptacles 302 may
be resilient so that they may be displaced enough to insert the
associated IMLA 115 into the housing 101. With the IMLA 115
inserted into the housing 101, the tab receptacle 204 may snap
back, and thus, the tabs 204 may be set within the openings 322 in
the tab receptacles 302. According to an aspect of the invention,
the tab receptacles 302 may contain the IMLAs within the housing in
all directions, and also allow for movement of the IMLAs 115 in all
directions within the housing.
[0023] To allow movement of the IMLAs 115 in the Y-direction, the
leadframes 215 need not extend all the way to the inner surface 305
of the tab receptacle 302. When an end of the overmolded housing
215 meets the inner surface 305 of the associated tab receptacle
302, the tab receptacle 302 prevents the overmolded housing 215
from moving any further in the Y-direction. The distance the IMLA
115 may move relative to the housing 101 in the Y-direction may be
controlled by regulating the distance between the end of the
overmolded housing 215 and the inner surface 305 of the housing
101. Thus, the tab receptacles 302 may contain the IMLAs 115 in the
Y-direction within the housing 101, while allowing movement of the
IMLAs in the Y-direction.
[0024] To allow movement of the IMLA 115 relative to the housing
101 in the X-and Z-directions, the receptacle openings 322 may be
made slightly larger than the cross-section (in the X-Z plane) of
the tabs 204 that the openings 322 are adapted to receive. When the
tab 204 meets one of the faces 332, the face 332 prevents the tab
204 (and, therefore, the overmolded housing 215) from moving any
farther in whichever direction the IMLA 115 is moving (e.g., the X-
or Z-direction). The relative difference in size between the
receptacle opening 322 and the cross-section of the tab 204
determines the amount the IMLA 115 may move relative to the housing
101 in the X- and Z-directions. Thus, the tab receptacles 302 may
contain the IMLAs 115 in the X- and Z-directions, while allowing
movement of the IMLAs in the X-Z plane. In an example embodiment of
the invention, the tabs 204 may have dimensions of about 0.20 mm in
the X-direction and about 1.30 mm in the Z-direction. The
receptacle openings 322 may have dimensions of about 0.23 mm in the
X-direction and about 1.45 mm in the Z-direction. The distance
between each end of the overmolded housing 215 and the respective
inner surface 305 of the housing 101 may be about 0.3 mm.
[0025] As shown in FIG. 1, a connector 100 according to the
invention may include a ball grid array 148. The ball grid array
148 may be formed by forming a respective solder ball 120 on the
terminal end 216 of each of the electrical contacts 211. Thus, the
ball grid array connector 100 may be set on a substrate, such as a
printed circuit board, for example, having a pad array that is
complementary to the ball grid array 148.
[0026] According to an aspect of the invention, the connector 100
may include a contact receiving substrate or wafer 107 that
contains the terminal ends of the contacts, while allowing for
movement of the terminal ends. The wafer 107 may be made of an
electrically insulating material, such as a plastic, for
example.
[0027] As best seen in FIG. 4, the wafer 107 may include an array
of apertures 456. Each aperture 456 may receive a respective
terminal portion 216 of a respective contact 211. Each aperture 456
is defined by a respective set of faces 478 that contain the
terminals in the X-and Y-directions. To allow movement of the
terminals in the X- and Y-directions, the apertures 456 may be
slightly larger than the cross-section (in the X-Y plane) of the
terminals 216 that the apertures 456 are adapted to receive. As
shown, the faces 478 may define the aperture 456 such that at least
one of the faces has a length that is greater than the width of the
contact. Thus, the terminal portion of the contact may sit freely,
or "float," within the aperture 456. That is, the terminal portion
of the contact need not necessarily touch any of the faces that
define the aperture 456. The relative difference in size between
the aperture 456 and the terminal 216 determines the amount the
terminal may move in the X- and Y-directions. Thus, the wafer 107
may contain the terminal portions 216 of the contacts 211 in the X-
and Z-directions, while allowing movement of the terminal portions
216 in the X-Y plane.
[0028] As shown, the apertures 456 may be generally square, though
it should be understood that the apertures 456 may be defined to
have any desired shape. In an example embodiment of the invention,
the terminal portions 216 of the contacts 211 may have dimensions
of about 0.2 mm by about 0.3 mm. The apertures 456 may have
dimensions of about 0.6 mm by about 0.6 mm.
[0029] To manufacture the connector 100, the IMLAs 115 may be
inserted and latched into the housing 101 as described above. The
wafer 107 may then be set on the ball-side faces 229 of the
overmolded housing 215, with the terminal portions 216 of the
contacts 211 extending into the apertures 456. Respective solder
balls 120 may then be formed on the terminal portions 216 of the
contacts 211 using known techniques. FIG. 5 depicts a plurality of
solder balls 120 formed on respective terminal portions 408 of
contacts that extend through overmolded housing 215. Note that FIG.
5 depicts the connector with solder balls but without the wafer,
though it is contemplated that the wafer will be set onto the
leadframes before the solder balls 120 are formed.
[0030] To form a solder ball on a terminal end of the contact,
solder paste may be deposited into the aperture 456 into which the
terminal end of the contact extends. A solder ball may be pressed
into the solder paste against the surface of the wafer 107. To
prevent the contact from being pulled into the housing through the
aperture, the diameter of the solder ball may be greater than the
width of the aperture. The connector assembly (which includes at
least the contact in combination with the housing and the wafer)
may be heated to a temperature that is greater than the liquidous
temperature of the solder. This causes the solder to reflow, form a
generally spherically shaped solder mass on the contact tail, and
metallurgically bond the solder ball to the contact.
[0031] Preferably, the aperture 456 has a width that is less than
the diameter of the solder ball so that the solder ball prevents
the contact from being able to be pulled into the housing.
Similarly, the diameter of the solder ball being greater than the
width of the aperture enables the wafer 107 to be contained between
the solder balls 120 and the overmolded housings of the leadframe
assemblies.
[0032] As shown in FIG. 6, the connector housing 115 may also
include one or more solder posts 160. The solder posts 160, which
may contain solder or solderable surfaces, may be adapted to be
received in orifices defined by a PCB board.
[0033] The IMLAs may be free to move with respect to the housing
115, as described above, prior to reflow of the solder balls. This
movement, or float, allows the IMLAs to self-align during reflow of
the solder balls. For example, when the solder balls liquefy during
reflow, surface tension in the liquid solder produces a
self-aligning effect. The present invention allows the IMLAs to
benefit from the self-aligning properties of the liquid solder
balls. Once reflow is complete, the contacts, housing, and solder
posts are fixed with respect to the PCB. The affixed solder posts
help prevent forces acting on the housing, in a direction parallel
to the PCB, to transmit to the solder balls.
[0034] It is to be understood that the foregoing illustrative
embodiments have been provided merely for the purpose of
explanation and are in no way to be construed as limiting of the
invention. Words which have been used herein are words of
description and illustration, rather than words of limitation.
Further, although the invention has been described herein with
reference to particular structure, materials and/or embodiments,
the invention is not intended to be limited to the particulars
disclosed herein. Rather, the invention extends to all functionally
equivalent structures, methods, and uses, such as are within the
scope of the appended claims. Those skilled in the art, having the
benefit of the teachings of this specification, may affect numerous
modifications thereto and changes may be made without departing
from the scope and spirit of the invention in its aspects.
* * * * *