U.S. patent application number 11/738541 was filed with the patent office on 2008-10-23 for method and apparatus for identifying broken pins in a test socket.
Invention is credited to Song Han, Douglas C. Kimbrough, Matthew S. Ryskoski, Christopher L. Wooten.
Application Number | 20080258704 11/738541 |
Document ID | / |
Family ID | 39591414 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080258704 |
Kind Code |
A1 |
Ryskoski; Matthew S. ; et
al. |
October 23, 2008 |
METHOD AND APPARATUS FOR IDENTIFYING BROKEN PINS IN A TEST
SOCKET
Abstract
A method includes scanning a test socket after removal of a
device under test to generate scan data. The scan data is compared
to reference data. A presence of at least a portion of a pin in the
test socket is identified based on the comparison. A test system
includes a test socket, a scanner, and a control unit. The test
socket is operable to receive devices under test. The scanner is
operable to scan a test socket after removal of a device under test
to generate scan data. The control unit is operable to compare the
scan data to reference data and identify a presence of at least a
portion of a pin in the test socket based on the comparison.
Inventors: |
Ryskoski; Matthew S.;
(Austin, TX) ; Wooten; Christopher L.; (Austin,
TX) ; Han; Song; (Austin, TX) ; Kimbrough;
Douglas C.; (Austin, TX) |
Correspondence
Address: |
WILLIAMS, MORGAN & AMERSON
10333 RICHMOND, SUITE 1100
HOUSTON
TX
77042
US
|
Family ID: |
39591414 |
Appl. No.: |
11/738541 |
Filed: |
April 23, 2007 |
Current U.S.
Class: |
324/66 ;
356/237.1; 73/865.8 |
Current CPC
Class: |
G01R 1/0433 20130101;
G01R 31/308 20130101; G01R 31/2863 20130101 |
Class at
Publication: |
324/66 ;
356/237.1; 73/865.8 |
International
Class: |
G01M 19/00 20060101
G01M019/00; G01N 21/00 20060101 G01N021/00; G01R 19/00 20060101
G01R019/00 |
Claims
1. A method, comprising: scanning a test socket after removal of a
device under test to generate scan data; comparing the scan data to
reference data; and identifying a presence of at least a portion of
a pin in the test socket based on the comparison.
2. The method of claim 1, wherein scanning the test socket further
comprises optically scanning the test socket, and the reference
data comprises an optical threshold.
3. The method of claim 2, wherein the optical threshold comprises
an intensity threshold.
4. The method of claim 1, wherein scanning the test socket further
comprises capturing an image of the test socket, and the reference
data comprises a reference image.
5. The method of claim 1, wherein scanning the test socket further
comprises electrically scanning the test socket, and the reference
data comprises an electrical threshold.
6. The method of claim 5, wherein the electrical threshold
comprises at least one of a continuity threshold and a signal
response threshold.
7. The method of claim 1, wherein scanning the test socket further
comprises scanning the test socket between insertions of devices
under test in the test socket.
8. The method of claim 1, further comprising removing the test
socket from service responsive to identifying the presence of the
pin.
9. The method of claim 1, further comprising automatically sending
an alert message responsive to identifying the presence of the
pin.
10. A test system, comprising: a test socket operable to receive
devices under test; a scanner operable to scan a test socket after
removal of a device under test to generate scan data; and a control
unit operable to compare the scan data to reference data and
identify a presence of at least a portion of a pin in the test
socket based on the comparison.
11. The system of claim 10, wherein the scanner comprises an
optical scanner, and the reference data comprises an optical
threshold.
12. The system of claim 11, wherein the optical threshold comprises
an intensity threshold.
13. The system of claim 10, wherein the scanner is operable to
capture an image of the test socket as the scan data, and the
reference data comprises a reference image of the test socket.
14. The system of claim 10, wherein the scanner is operable to
electrically scan the test socket, and the reference data comprises
an electrical threshold.
15. The system of claim 14, wherein the electrical threshold
comprises at least one of a continuity threshold and a signal
response threshold.
16. The system of claim 14, wherein the test socket comprises:
openings for receiving pins of a device under test; at least a
first contact disposed in the opening; and at least a second
contact disposed in the opening.
17. The system of claim 16, wherein the scanner is operable to
determine if continuity exists between the first and second
contacts, and the scan data comprises continuity results for each
of the openings.
18. The system of claim 16, wherein the scanner is operable to
inject a signal on the first contact and measure a response on the
second contact, and the scan data comprises response results for
each of the openings.
19. The system of claim 10, wherein the scanner is operable to scan
the test socket between insertions of devices under test in the
test socket.
20. The system of claim 10, wherein the control unit is further
operable to remove the test socket from service responsive to
identifying the presence of the pin.
21. The system of claim 10, wherein the control unit is further
operable to send an alert message responsive to identifying the
presence of the pin.
22. A system, comprising: means for scanning a test socket after
removal of a device under test to generate scan data; means for
comparing the scan data to reference data; and means for
identifying a presence of at least a portion of a pin in the test
socket based on the comparison.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to semiconductor
device testing and, more particularly, to a method and apparatus
for identifying broken pins in a test socket.
[0003] Semiconductor die are normally formed in large quantities on
wafers of semiconductor material, for example, silicon. After die
are singulated from the wafers, they may be individually packaged
in plastic or ceramic packages, for example. A lead frame may
support the die for wire bonding and packaging and provide the lead
system for the completed package. In general, electrical circuitry
formed on the die is coupled to bond pads on the die to facilitate
interconnection of the electrical circuitry with the outside world.
During the wire bonding and packaging process, each bond pad is
electrically connected by way of wire leads to the lead frame. The
electrical connection includes a wire bond formed on the bond pad,
a wire lead and a wire bond formed on the lead frame. An
encapsulating material protects and insulates the die, and the die
is mounted in a package having external pins for interconnecting
the electrical circuitry on the die, via the wire bonds, to the
outside world.
[0004] Packaged devices are typically inserted into sockets on
automated test equipment to perform various functional and
performance tests prior to delivery to a customer. One example of a
test performed on a packaged die is commonly referred to as burn-in
testing. Burn-in testing involves accelerated stressing of the
parts by subjecting the device to stress level operating conditions
for the purpose of accelerating early failures that may occur when
the device is assembled in a product. Burn-in generally involves
elevating the temperature of a device beyond normal operating
conditions and electrically exercising the device. Of course, other
types of test programs may be implemented to verify/establish
performance grades and operating characteristics.
[0005] In a typical test device, multiple sockets are employed to
allow testing of multiple devices in parallel or in sequence. The
sockets are mounted to a circuit board through which various
electrical signals are provided under the direction of a test
program to implement the required tests. Devices under test (DUT)
are inserted into the sockets by automatic handling equipment that
aligns each DUT with a socket and applies an insertion force to
seat the device in the socket.
[0006] During the insertion process, it is possible that one or
more pins on the DUT may not be aligned sufficiently with the
corresponding contact holes in the socket to allow the pin to be
properly inserted or seated. In some cases, the pin may become
bent, broken, or wedged into the socket. Depending on the
particular pin damaged and the nature of the damage, the device may
or may not pass the functional test.
[0007] When the device is removed from the socket, a damaged pin
may remain in the socket. Subsequently, when a different DUT is
inserted into the socket, the corresponding pin may not be able to
be inserted into the socket as the contact hole is plugged. As a
result the pin on the second DUT may itself become damaged.
[0008] Often, a broken pin may not be identified until a failure
trend is recognized and a subsequent manual inspection is performed
to verify functionality of the socket. During the time delay
between the problem onset and the troubleshooting, multiple devices
may be damaged or the test results associated with the devices may
be compromised.
[0009] This section of this document is intended to introduce
various aspects of art that may be related to various aspects of
the present invention described and/or claimed below. This section
provides background information to facilitate a better
understanding of the various aspects of the present invention. It
should be understood that the statements in this section of this
document are to be read in this light, and not as admissions of
prior art. The present invention is directed to overcoming, or at
least reducing the effects of, one or more of the problems set
forth above.
BRIEF SUMMARY OF THE INVENTION
[0010] The following presents a simplified summary of the invention
in order to provide a basic understanding of some aspects of the
invention. This summary is not an exhaustive overview of the
invention. It is not intended to identify key or critical elements
of the invention or to delineate the scope of the invention. Its
sole purpose is to present some concepts in a simplified form as a
prelude to the more detailed description that is discussed
later.
[0011] One aspect of the present invention is seen in a method that
includes scanning a test socket after removal of a device under
test to generate scan data. The scan data is compared to reference
data. A presence of at least a portion of a pin in the test socket
is identified based on the comparison.
[0012] Another aspect of the present invention is seen in a test
system including a test socket, a scanner, and a control unit. The
test socket is operable to receive devices under test. The scanner
is operable to scan a test socket after removal of a device under
test to generate scan data. The control unit is operable to compare
the scan data to reference data and identify a presence of at least
a portion of a pin in the test socket based on the comparison.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0013] The invention will hereafter be described with reference to
the accompanying drawings, wherein like reference numerals denote
like elements, and:
[0014] FIG. 1 is a simplified block diagram of a testing system in
accordance with one illustrative embodiment of the present
invention;
[0015] FIG. 2 is a top view of a socket employed in the test system
of FIG. 1;
[0016] FIG. 3 is a partial diagram of the system of FIG. 1
illustrating an optical scanner;
[0017] FIG. 4 is a partial diagram of the system of FIG. 1
illustrating a scanner that captures an image of the test
socket;
[0018] FIG. 5 is a partial diagram of the system of FIG. 1
illustrating an electrical scanner;
[0019] FIGS. 6A, 6B, and 6C illustrate various exemplary contact
arrangements that may be used in the test socket in conjunction
with the electrical scanner of FIG. 5; and
[0020] FIG. 7 is a simplified flow diagram for identifying a damage
pin in the test socket of FIG. 2 in accordance with another
illustrative embodiment of the present invention.
[0021] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and are herein described in
detail. It should be understood, however, that the description
herein of specific embodiments is not intended to limit the
invention to the particular forms disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0022] One or more specific embodiments of the present invention
will be described below. It is specifically intended that the
present invention not be limited to the embodiments and
illustrations contained herein, but include modified forms of those
embodiments including portions of the embodiments and combinations
of elements of different embodiments as come within the scope of
the following claims. It should be appreciated that in the
development of any such actual implementation, as in any
engineering or design project, numerous implementation-specific
decisions must be made to achieve the developers' specific goals,
such as compliance with system-related and business related
constraints, which may vary from one implementation to another.
Moreover, it should be appreciated that such a development effort
might be complex and time consuming, but would nevertheless be a
routine undertaking of design, fabrication, and manufacture for
those of ordinary skill having the benefit of this disclosure.
Nothing in this application is considered critical or essential to
the present invention unless explicitly indicated as being
"critical" or "essential."
[0023] The present invention will now be described with reference
to the attached figures. Various structures, systems and devices
are schematically depicted in the drawings for purposes of
explanation only and so as to not obscure the present invention
with details that are well known to those skilled in the art.
Nevertheless, the attached drawings are included to describe and
explain illustrative examples of the present invention. The words
and phrases used herein should be understood and interpreted to
have a meaning consistent with the understanding of those words and
phrases by those skilled in the relevant art. No special definition
of a term or phrase, i.e., a definition that is different from the
ordinary and customary meaning as understood by those skilled in
the art, is intended to be implied by consistent usage of the term
or phrase herein. To the extent that a term or phrase is intended
to have a special meaning, i.e., a meaning other than that
understood by skilled artisans, such a special definition will be
expressly set forth in the specification in a definitional manner
that directly and unequivocally provides the special definition for
the term or phrase.
[0024] Referring now to the drawings wherein like reference numbers
correspond to similar components throughout the several views and,
specifically, referring to FIG. 1, the present invention shall be
described in the context of a test system 100. The test system 100
includes a test unit 110 including a test socket 120 and test
circuitry 130, a scanner 140, a control unit 150, and a database
160. The test system 100 receives a device under test 170 in the
test socket 120 and performs testing operations to verify operation
or determine performance characteristics of the device under test
170.
[0025] For ease of illustration and to avoid obscuring features of
the embodiments of the present invention, not all parts of the test
system 100 are depicted. For example, an automated material handler
(e.g., robot arm) is typically employed to engage the device under
test 170 in the test socket 120. Moreover, the test unit 110 may
include multiple test sockets 120 to allow sequential or parallel
testing of multiple devices under test 170 by the test circuitry
130. Generally, the particular type of testing performed by the
test unit 110 is not material to the practice of the embodiments of
the present invention. Those of ordinary skill in the art are
familiar with the testing operations that may be performed and the
configuration of the test circuitry 130 required to implement the
tests. Although the scanner 140 and control unit 150 are
illustrated as being distinct units, it is contemplated that they
may be integrated into a single unit or one or both may be
integrated into the test unit 110.
[0026] The scanner 140 scans the test socket 120 (e.g., optically
or electrically) between insertions of devices under test 170 to
identify damaged pins that may have become separated from any
device under test 170 and lodged in the test socket 120 during the
insertion and removal processes. By scanning the socket between
insertions, the throughput of the test system 100 is not reduced.
The frequency of the scanning may vary depending on the particular
embodiment. For example, the test socket 120 may be scanned between
each insertion of a device under test 170. Alternatively, the scan
may be completed at a fixed frequency (e.g., every five
insertions).
[0027] The scanner 140 communicates scan results to the control
unit 150, which analyzes the scan data to identify a potential pin
lodged in the test socket 120. The control unit 150 may store the
scan data in the database 160. In some embodiments, the control
unit 150 may store all scan results, while in other embodiments,
the control unit 150 may store only scan data associated with
suspected damaged pins.
[0028] Turning briefly to FIG. 2, a top view of the test socket 120
is shown. The test socket 120 includes a plurality of openings 200
for receiving pins of the device under test 170. A damaged pin 210
is lodged in one of the openings 200. The damaged pin 210 causes
the characteristics of the test socket 120 to change as compared to
a reference state. The measurements conducted by the scanner 140
aid the control unit 150 in identifying the changed characteristics
to identify the damaged pin 210. The particular arrangement of test
socket 120 with respect to the number and arrangement of openings
200 may vary depending on the particular embodiment and the
structure of the device under test 170.
[0029] In some embodiments, the scanner 140 is an optical scanner
that scans the test socket 120 through illumination or by capturing
an image of the test socket 120. In other embodiments, the scanner
140 is an electrical scanner that evaluates the electrical
characteristics of the test socket 120 (e.g., resistance) to
identify the presence of the damaged pin 210.
[0030] In a first embodiment shown in FIG. 3, the scanner 140 may
include a light source 300 (e.g., laser) and a detector 310
operable to measure characteristics (e.g., intensity at one or more
frequencies) of light originating from the light source and
reflected by the test socket 120 to the detector 310. The
orientation of the light source 300 with respect to the detector
310 may vary depending on the particular embodiment. Also, the
geometries of the light source 300 and detector 310 may vary from
the example illustrated. In the illustrated embodiment, the light
source 300 and detector 310 are arranged in a perpendicular
orientation with respect to the test socket 120.
[0031] The optical scan data is compared to reference data to
identify a discrepancy that may indicate the presence of a pin in
the test socket 120. For example, the measured scan data may be
compared to a reference intensity threshold. The presence of a pin
may be identified in response to the measured intensity violating
the predetermined threshold, i.e., either in the positive or
negative direction depending on the optical characteristics of the
test socket 120 and/or the pins. The scanner 140 may scan the
entire test socket 120 or, alternatively, the scanner 140 may scan
only a portion of the test socket 120 and report results for each
partial scan to the control unit 150.
[0032] In another embodiment, illustrated in FIG. 4, the scanner
140 may capture an image 400 of the test socket 120 and compare the
captured image 400 to a reference image 410 to identify the damaged
pin 210. The reference image 410 may be generated in advance for
the test socket 120 or the reference image 410 may generated using
one or more previous scans of the test socket 120 for which it was
know that no damaged pin 210 was present. By updating the reference
image 410 a changing environment in the proximity of the test
system 100 (e.g., ambient lighting) or changes to the test socket
120 due to usage may be accounted for, thereby reducing the
potential for an errant scan result.
[0033] Various techniques may be used for comparing the captured
image 400 to the reference image 410. For example, pixels or groups
of pixels may be compared to identify the presence of a damaged pin
210. In an embodiment where the test socket 120 is a dark color, a
metallic pin would appear as a significantly brighter group of
pixels. Hence, the damaged pin 210 may be identified in response to
the average color of a group of pixels in the captured image 400
differing from the expected average color from the reference image
410. Other comparison techniques may also be used. In some
embodiments, a pixel by pixel comparison may be made and various
statistics may be determined, such as mean absolute error, mean
squared error, root mean squared error, peak squared error, peak
signal to noise ration, different pixel count, etc. One or more of
the difference statistics may be compared to determine if the
captured image 400 is sufficiently different than the reference
image 410 to suggest the presence of one or more damaged pins
210.
[0034] In another embodiment of the present invention shown in FIG.
5, the scanner 140 may electrically coupled to the test socket 120
to perform an electrical scan of the test socket 120 to identify
the damaged pin 210. The scanner 140 may communicate with or may be
integrated into the test circuitry 130. The scanner 140 performs an
electrical test on the test socket 120 to determine the presence of
a damaged pin 210. An exemplary electrical test for determining the
presence of a damaged pin 210 is a continuity test or a signal
injection test.
[0035] Turning briefly to the cross section diagrams of FIGS.
6A-6C, the test socket 120 may include contacts 600, 610 that are
normally not in communication with one another. For example, the
contact 600 may represent the test contact used for functional
testing of the device under test 170 and the contact 610 may be a
scan contact used only for the identification of the damaged pin
210.
[0036] During the scan, the scanner 140 may check for continuity
between the test contact 600 and the scan contact 610.
Alternatively, the scanner 140 may inject a signal at the scan
contact 610 and query the test circuitry 130 to determine if the
signal is present on the test contact 600. If continuity or a
response to the signal is present, it is likely that a damaged pin
210 is lodged within the opening 200.
[0037] The orientation of the contacts 600, 610 may vary depending
on the particular embodiment. For example, both contacts 600, 610
may be disposed on the sidewall of the opening 200, as shown in
FIG. 6A. In another embodiment shown in FIG. 6B, one contact 600,
610 may be disposed on a sidewall of the opening 200, and the other
contact 600, 610 may be located at the bottom of the opening 200.
In yet another embodiment shown in FIG. 6C, two scan contacts 610,
620 may be provided to allow the scan to be completed independently
of the test contact 600. In such an embodiment, the scanner 140
need not communicate with the test circuitry 130 to determine if
continuity or a signal response is present.
[0038] Returning to FIG. 1, the scanner 140 provides the scan
results to the control unit 150, which analyzes the scan results to
identify the presence of a damaged pin 210. In the case of an
optical scanner 140, the control unit 150 compares the scan data to
reference data, for example, by comparing a measured intensity to a
reference intensity or a captured image to a reference image to
identify a damaged pin 210. In the case of an electrical scanner
140, the control unit 150 compares the measured electrical scan
data to a reference data (e.g., no continuity or no signal
response) to identify the potential presence of the damaged pin
210.
[0039] After identifying a potential damaged pin 210, the control
unit 150 may take various corrective actions. In one embodiment,
the control unit 150 may inform the test unit 110 that the test
socket 120 is suspect, and the test unit 110 will prevent any
additional devices under test 170 from being loaded into the test
socket 120. This action will prevent other devices under test 170
from being damaged by trying to insert a pin from a subsequent
device under test 170 into an occupied opening 200 in the test
socket 120. If the test unit 110 is equipped with multiple test
sockets 120, the remaining sockets may be employed for testing
devices under test 170 without interruption. Another potential
corrective action that the control unit 150 may implement is to
send an electronic message (e.g., email) to a tool operator or
activate an alarm or status indicator identifying the potential
damaged pin 210. Yet another action the control unit 150 may take
is to send a scheduling request to a maintenance system (not shown)
in the fabrication facility. The maintenance system may
automatically take the test unit 110 out of service and/or schedule
a maintenance activity to inspect and repair the suspected test
socket 120.
[0040] The control unit 150 may also take corrective actions with
respect to the device or devices under test 170 tested since the
previous successful scan. The last device under test 170 tested may
be designated a being potentially faulty. In the embodiment where
multiple insertions are performed between each scan, all devices
under test 170 processed between scans may be identified as being
potentially faulty. Depending on which device under test 170 was
responsible for the damaged pin 210, those inserted after the
faulty device under test 170 may have bent or damaged pins of their
own.
[0041] Turning now to FIG. 7, a simplified flow diagram of a method
for determining the availability of a test socket is provided. In
method block 700, a test socket is scanned between insertions of
devices under test to generate scan data. In method block 710, the
scan data is compared to reference data (e.g., reference image,
intensity threshold, electrical threshold, etc.). In method block
720, the presence of a pin lodged in the test socket is identified
based on the comparison.
[0042] The particular embodiments disclosed above are illustrative
only, as the invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having
the benefit of the teachings herein. Furthermore, no limitations
are intended to the details of construction or design herein shown,
other than as described in the claims below. It is therefore
evident that the particular embodiments disclosed above may be
altered or modified and all such variations are considered within
the scope and spirit of the invention. Accordingly, the protection
sought herein is as set forth in the claims below.
* * * * *