Contact probe unit

An electronic device is interposed between a pair of contact units of a contact probe unit without using any soldering or other permanent connecting arrangement. Alternatively, the electronic device is interposed between a securing plate and a contact unit provided with a pair of arrays of contact modules. Thus, the electronic device may be incorporated in the contact probe unit without requiring any permanent connecting arrangement such as soldering which may produce any contaminants or other undesirable substances or cannot be readily detached and attached. This is particularly important in a clean room environment. According to a preferred embodiment of the present invention, said electronic device comprises an integrated circuit mounted on said sheet member. For instance, the electronic device may consist of a TAB for driving an LCD panel so that the LCD panel may be tested in a realistic condition.

CROSS REFERENCE TO RELATED PATENTS AND CO-PENDING APPLICATIONS 
The following patents and co-pending patent applications are directed to 
subject matters similar to those of the present application, and are 
commonly assigned to NHK Spring Co., Ltd. Reference should be made to the 
disclosure of these patents and patent applications, and the contents of 
the copending applications are hereby incorporated with the present 
application by reference. 
______________________________________ 
application 
Ser. No. Filing Date Remarks 
______________________________________ 
unknown even date 
08/148,488 
November 8, 1993 
U.S. Pat. No. 
5,414,369 
issued May 9, 1995 
08/148,489 
November 8, 1993 
U.S. Pat. No. 
5,410,260 
issued April 25, 1995 
08/013,465 
February 4, 1993 
U.S. Pat. No. 
5,394,099 
issued February 28, 1995 
07/739,051 
July 30, 1991 U.S. Pat. No. 
5,200,695 
issued April 6, 1993 
07/737,763 
July 30, 1991 U.S. Pat. No. 
5,189,364 
issued February 23, 1993 
07/600,198 
October 19, 1990 
Div. of 07/536,516 
U.S. Pat. No. 
5,084,673 
issued January 28, 1992 
07/536,516 
June 12, 1990 U.S. Pat. No. 
5,003,255 
issued March 26, 1991 
07/424,511 
October 20, 1989 
U.S. Pat. No. 
5,004,977 
issued April 2, 1991 
______________________________________ 
TECHNICAL FIELD 
The present invention relates to a contact probe unit, and in particular to 
a contact probe unit which is suitable for testing LCD panels and arrays 
of electronic components including points to be tested arranged at a high 
density. 
BACKGROUND OF THE INVENTION 
Conventionally, contact probe units have been widely used for testing 
electroconductive patterns of printing circuit boards and various 
electronic devices, and there have been attempts to modify them into more 
suitable forms for testing LCD panels. In testing an LCD panel, it is 
desirable to test it at a condition which closely simulates the actual 
condition of the final product, and it is therefore desirable to test the 
LCD panel by using a TAB (an LSI chip used for driving an LCD panel) 
identical to that used in the final product. Because a large number of 
wires must be connected between the LCD panel and the TAB, preferably, the 
TAB should be incorporated in the contact probe unit itself. 
However, the TAB may have to be replaced from time to time either due to a 
failure of the TAB or a change in the specification of the product. If the 
TAB is connected to the contact modules by soldering, a substantial amount 
of work is necessary for replacing the TAB. Also, soldering tends to 
produce a large amount of foreign particles, and it is detrimental to the 
clean room environment in which LCD panels are produced. Therefore, when 
replacing the TAB, it would be necessary to take the contact probe unit 
out of the clean room environment, and replace the TAB. Furthermore, it 
would be necessary to thoroughly clean the contact probe unit before 
bringing the contact probe unit back into the clean room. 
In some of the contact probe units proposed by the present inventor and 
disclosed in the above mentioned patents and patent applications, each 
contact module comprises a compression coil spring received in a support 
hole or a tubular receptacle, and a pair of needle members attached to the 
corresponding ends of the compression coil spring to urge them outward. 
The extent by which each of the needle members projects from the 
corresponding end of the support hole or the receptacle is determined by 
suitable stopper means. The inventor has considered the possibility of 
adapting such contact probe units for incorporating a TAB in such a manner 
as to allow replacement of the TAB in a simple manner. 
BRIEF SUMMARY OF THE INVENTION 
In view of such problems of the prior art, a primary object of the present 
invention is to provide a contact probe unit which can incorporate therein 
an electronic device in a readily replaceable manner. 
A second object of the present invention is to provide a contact probe unit 
which can incorporate therein an electronic device in such a manner as to 
allow replacement of the electronic device without producing any foreign 
matters detrimental to maintaining a clean room environment. 
A third object of the present invention is to provide a contact probe unit 
which can incorporate therein an electronic device without substantially 
increasing the size of the contact probe unit. 
A fourth object of the present invention is to provide a contact probe unit 
which can incorporate therein an electronic device without substantially 
increasing the complexity of the contact probe unit. 
These and other objects of the present invention can be accomplished by 
providing a contact probe unit for electrically accessing parts to be 
tested, comprising: a first contact unit comprising a base having an upper 
surface and a lower surface, and a plurality of contact modules arranged 
in the base, each of the contact modules comprising an upper needle member 
and a lower needle member projecting from the upper and lower surfaces of 
the base, respectively, and spring means for resiliently urging at least 
one of the needle members in a direction to project from the associated 
surface of the base, the lower needle members being adapted to be 
contacted with the parts to be electrically accessed; a second contact 
unit comprising a base having an upper surface and a lower surface, and a 
plurality of contact modules arranged in the base, each of the contact 
modules comprising an upper needle member and a lower needle member 
projecting from the upper and lower surfaces of the base, respectively, 
and spring means for resiliently urging at least one of the needle members 
in a direction to project from the associated surface of the base; an 
electronic device including a sheet member carrying a first array of 
terminals on a lower surface thereof and a second array of terminals on an 
upper surface thereof; means for assembling the first and second contact 
units one over the other with at least part of the sheet member of the 
electronic device interposed therebetween in such a manner as to contact 
the upper needle members of the first contact unit with the first array of 
terminals, and contact the lower needle members of the second contact unit 
with the second array of terminals; and means for connecting the upper 
needle members of the second contact unit to an external circuit. 
According to the present invention, it is also possible to incorporate all 
of the contact modules in a common single base. In this case, a first 
array of contact modules and a second array of contact modules are 
arranged in a first part of the base and a second part of the base, 
respectively, each of the contact modules comprising an upper needle 
member and a lower needle member projecting from the upper and lower 
surfaces of the base, respectively, and spring means for resiliently 
urging at least one of the needle members in a direction to project from 
the associated surface of the base, the lower needle members of the first 
array of contact modules being adapted to be contacted with the parts to 
be electrically accessed; and an electronic device including a sheet 
member carrying a first array of terminals and a second array of terminals 
on different parts of a lower surface thereof is interposed between a 
securing plate for securing the electronic device on the upper surface of 
the base in such a manner as to contact the upper needle members of the 
first contact module array with the first array of terminals, and contact 
the upper needle members of the second contact module array with the 
second array of terminals. The lower needle members of the second contact 
module array are connected to an external circuit by suitable means. 
Thus, the electronic device may be incorporated in the contact probe unit 
without requiring any soldering or other connecting means which may 
produce any contaminants or other undesirable substances or cannot be 
readily detached and attached. This is particularly important in a clean 
room environment. 
According to a preferred embodiment of the present invention, the 
electronic device comprises an integrated circuit mounted on the sheet 
member. For instance the electronic device may consist of a TAB for 
driving an LCD panel so that the LCD panel may be tested in a realistic 
condition. 
Preferably, the base comprises a layered structure including an upper 
insulating plate, an intermediate insulating plate and a lower insulating 
plate, each of the contact modules being received in a through hole passed 
through the base, and each of the through holes consists of a relatively 
large support hole passed through the intermediate insulating plate, a 
pair of relatively small support holes passed through the upper and lower 
insulating plates, all in a substantially coaxial relationship, each of 
the needle members being provided with a shoulder surface (which for 
instance may be defined by a radial flange) which engages with an annular 
shoulder surface defined between the large support hole and a 
corresponding one of the small support holes so as to determine an extent 
by which the corresponding needle member resiliently projects from the 
corresponding surface. Because the needle members are received in the 
through holes formed directly in the base without using any tubular 
receptacles, each contact module may have an extremely small outer 
diameter, and can be arranged close to one another. This is important when 
applying the contact probe unit to integrated circuits and other 
electronic devices where densely distributed parts are to be accessed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a perspective view of a first embodiment of the contact probe 
unit according to the present invention as it is applied to an LCD panel 
2. The LCD panel 2 is lighted up for testing purpose by driving each cell 
thereof before it is finally connected to a TAB which serves as an LSI for 
driving the LCD panel 2. 
As shown in FIG. 1, the contact probe unit 1 comprises a lower contact unit 
4 incorporating a plurality of contact modules 3 for contact with input 
terminals 2a of the LCD panel 2, an upper contact unit placed over the 
lower contact unit 4 incorporating similar contact modules for contact 
with a printed circuit board 8 which leads to an external testing circuit, 
and a TAB assembly consisting of a TAB 6 and a securing plate 7 interposed 
between the upper and lower contact units 4 and 5. 
Referring to FIGS. 2 and 3, the lower contact unit 4 is provided with 
layered structure comprising a relatively thin lower insulating plate 
member 10, a pair of relatively thick intermediate insulating plate 
members 11, and a relatively thin upper insulating plate member 12 in that 
order. The intermediate plate members 11 are each provided with a 
plurality of relatively large support holes 11a, and the upper and lower 
plate members 12 and 10 are each similarly provided with a relatively 
small support hole 12a or 10a. These support holes 10a, 11a and 12a are 
mutually aligned so as to form a plurality of through holes passed 
vertically through the lower contact unit 4. 
A compression coil spring 13 is coaxially received in each of the support 
holes 11a in a slightly prestressed condition, and the two ends of each 
compression coil spring 13 are integrally connected to the base ends of 
the needle members 14 and 15, respectively, for instance by soldering or 
brazing. The soldering connection between the compression coil spring and 
the needle members results in a small fluctuation in electric resistance 
(at most a few %), and a highly stable measurement or test can be made 
possible. Each of the needle members 14 and 15 is provided with a radial 
flange defining an annular shoulder surface which rests on a corresponding 
annular shoulder surface defined between the corresponding larger support 
hole 11a and the associated one of the smaller support holes 10a or 12a. 
Thus, each of the needle members 14 and 15 is urged outward by the 
corresponding compression coil spring 13, but is prevented from coming out 
of the support hole by virtue of the engagement between the radial flange 
and the associated shoulder surface of the support hole. The contact 
modules 3 each consisting of the coil spring 13 and the two needle members 
14 and 15 are provided by the same number as the number of the input 
terminals 2a. 
The insulating plates 10 to 12 are registered with each other by locating 
pins 16 passed through them, and are integrally joined together by 
threaded bolts 17 passed through them. The locating pins 16 ensure that 
the support holes 10a to 12a are kept in a coaxial relationship. The upper 
end of each of the locating pins 16 projects from the upper surface of the 
upper insulating plate member 12 by a certain length, and the 
aforementioned securing plate 7 is positioned on the upper surface of the 
upper insulating plate member 12 with the aid of these locating pins 16. 
The TAB 6 is secured to the lower surface of the securing plate 7. The TAB 
6 is identical to the TABs incorporated in the completed LCD panels for 
driving them, and consists of an LSI chip having terminals printed on a 
sheet member 6a. The TAB main body is received in a recess 7a provided in 
the lower surface of the securing plate 7 which is in turn secured to a 
front end of the upper surface of the lower contact unit 4 with threaded 
bolts 17. The terminals printed on the upper surface of the sheet member 
6a are designed to be connected to the printed circuit board 8 via the 
upper contact unit 5 as described hereinafter, and the terminals printed 
on the lower surface of the sheet member 7a are designed to be connected 
to the input terminals 2a of the LCD panel 2 via the lower contact unit 4. 
The upper end of each of the needle members 14 and 15 projects by a certain 
length from the upper surface or the lower surface of the lower contact 
unit 4 as the case may be. Therefore, when the TAB 6 is placed onto the 
upper surface of the lower contact unit 4, the upper needle members 14 are 
pushed into the support holes 12a against the spring force of the 
compression coil springs 13, and a favorable electric contact can be 
established between the TAB 6 and the terminals 2a of the LCD panel 2. 
The sheet member 6a of the TAB 6 extends to the rear part of the upper 
surface of the lower contact unit 4, and the upper contact unit 5 is 
placed over the upper surface of the rear part of the lower contact unit 4 
with the sheet member 6a interposed between them. 
The upper contact unit 5 has a similar layered structure as the lower 
contact unit 4, and comprises a lower insulating plate member 20, a pair 
of intermediate insulating plate members 21, and an upper insulating plate 
member 22 in that order. The intermediate plate members 21 are each 
provided with a plurality of relatively large support holes 21a, and the 
upper and lower plate members 22 and 20 are each similarly provided with a 
relatively small support hole 22a or 20a. These support holes 10a, 11a and 
12a are mutually aligned so as to form a plurality of through holes passed 
vertically through the upper contact unit 5. A contact module consisting 
of a compression coil spring 23 and a pair of needle members 24 and 25 
attached to the respective ends of the compression coil spring 23 is 
received in each of these through holes. 
Likewise, locating pins 26 are passed through the upper contact unit 5 to 
secure the insulating plates 20 to 22 in properly registered condition, 
and the upper ends of the locating pins 26 are fitted into the associated 
holes of a securing plate 9 clamping the printed circuit board 8 between 
the securing plate 9 and the upper surface of the upper contact unit 5. 
The securing plate 9 is secured to the upper contact unit 5 with threaded 
bolts 27. 
In the assembled state, the terminals printed on the upper surface of the 
sheet member 6a of the TAB 6 are resiliently contacted by the lower needle 
members 25, and the printed terminals of the printed circuit board 8 are 
resiliently contacted by the upper needle members 24. The printed circuit 
board 8 is in turn connected, via a connector, to a flat cable 28 leading 
to an external control or testing circuit. Typically, the number of 
individual wires in the flat cable 28 may be substantially less than the 
number of the terminals 2a of the LCD panel 2. 
The securing plate 9 extends rearward beyond the rear end of the upper 
contact unit 5, and a frame member 29 is interposed between the upper 
surface of the lower contact unit 4 and the lower surface of the securing 
plate 9. As best shown in FIG. 2, the thickness or the vertical dimension 
of the frame member 29 is identical to the combined vertical dimension of 
the upper contact unit 5 and the sheet member 6a. The lower ends of the 
locating pins 26 for the upper contact unit 5 project from the lower 
surface of the upper contact unit 5, and fit into associated holes formed 
in the lower contact unit 4. Thus, the locating pins 26 ensure proper 
registrations not only between the insulating plates 20 to 22 but also 
between the upper contact unit 5 and the lower contact unit 4 and between 
the securing plate 9 and the upper contact unit 5. Threaded bolts 27 and 
30 are passed between the upper securing plate 9 and the upper contact 
unit 5 and between the upper securing plate 9 and the frame member 5, 
respectively. Threaded bolts not shown in the drawings are passed through 
the lower contact unit 4, and are threaded into the frame member 29. Thus, 
the two contact units 4 and 5 are placed one over the other, and are 
mutually joined together via the frame member 29. 
The LCD panel 2 can be tested by mounting a plurality of contact probe 
units 1 as described above on the frame member 29 arranged along the X- 
and Y-axes of the LCD panel 2, and contacting the lower needle members 15 
of the lower contact unit 4 to the terminals 2a of the LCD panel 2. A 
control signal is supplied to the printed circuit board 8 for activating 
the TAB 6, and the TAB 6 in turn drives and lights up the LCD panel 2. 
The contact probe unit 1 is assembled by joining a number of component 
parts together by using threaded bolts, and can be dissembled by 
unfastening these threaded bolts. As best illustrated in FIG. 3, the upper 
contact unit 5 can be separated from the lower contact unit 4 by 
unfastening the threaded bolts 30, and the securing plate 9 can be removed 
and the printed circuit board 8 can be exposed by unfastening the threaded 
bolts 27. By unfastening the threaded bolts 17, the securing plate 7 can 
be separated from the lower contact unit 4 to expose the TAB 6. 
According to the present invention, the connection to the TAB 6 and the 
printed circuit board 8 is accomplished via contact modules instead of 
soldering. Therefore, in case of a failure of the TAB 6, it can be readily 
removed from the contact probe unit 1, and replaced by a new TAB simply by 
unfastening and fastening threaded bolts. This can be accomplished not 
only in a simple manner but also in such a manner as not to disrupt a 
clean room environment. 
FIGS. 4 and 5 show a second embodiment of the present invention, and in 
these drawings the parts corresponding to those of the previous embodiment 
are denoted with like numerals. 
In this embodiment, the lower contact unit 4 is provided with larger 
support holes 11b and smaller support holes 10b and 12b similar to the 
holes 11a, 10a and 12a in a parallel relationship. The support holes 11b, 
10b and 12b likewise jointly form through holes passed vertically through 
the lower contact unit 4, and a contact module consisting of a compression 
coil spring 33 and a pair of needle members 34 and 35 attached to the 
corresponding ends of the compression coil spring 33 is received in each 
of these through holes. 
A securing plate 7 is attached to the upper surface of the lower contact 
unit 4 with threaded bolts 17, and a TAB 6 is attached the bottom surface 
of a recess 7a formed in the lower surface of the securing plate 7. The 
TAB 6 is provided with a sheet member 6a extending in both forward and 
rearward directions, and an array of laterally arranged printed terminals 
are formed on each of the forward and rearward extending parts of the 
sheet member 6a. The positions of the contact modules are arranged in two 
different arrays in such a manner that the upper needle members 14 and 34 
of the first and second arrays of contact modules are brought into contact 
with the first and second arrays of printed terminals, respectively. 
In this embodiment, a printed circuit board 8 is attached to the lower 
surface of a rear part of the lower contact unit 4, and is secured thereto 
by a securing plate 9 which is in turn secured to the lower insulating 
plate 10 with threaded bolts 27. The control signal supplied to the 
printed circuit board 8 is transmitted to the lower needle members 35, and 
then to the upper needle members 34 of the second contact module array. 
The upper needle members 34 are in contact with the array of terminals in 
the rear extension of the sheet member 9. The array of terminals in the 
front extension of the sheet member 9 are in contact with the upper needle 
members 14 of the first contact module array, and are thus electrically 
connected to the terminals 2a of the LCD panel 2 via the compression coil 
springs 13 and the lower needle members 15. 
According to this embodiment, as there is no upper contact unit, and the 
entire assembly is incorporated into the lower contact unit, the overall 
height of the contact probe unit can be substantially reduced as compared 
with the previous embodiment. The reduced height of the contact probe unit 
improves the visibility of the front surface of the LCD panel at the time 
of testing. The TAB 6 may have to be replaced from time to time, and it 
can be readily achieved by 10 unfastening the threaded bolts 17, and 
removing the securing plate 7. The printed circuit board 8 can be also 
readily removed by unfastening the threaded bolts 27 and removing the 
securing plate 9. As opposed to the soldering which tends to produce 
foreign particles, the work involved in replacing these component parts 
according to the present invention produces almost no particles which 
could be detrimental to clean room environment. 
Thus, according to the present invention, an electronic device may be 
incorporated in the contact probe unit without requiring any permanent 
connecting arrangement such as soldering which may produce any 
contaminants or other undesirable substances or cannot be readily detached 
and attached. This is particularly important in a clean room environment. 
Also, the work involved in replacing the electronic device is very little, 
and can maintain and remodel the contact probe unit quickly and 
economically. 
Although the present invention has been described in terms of specific 
embodiments thereof, it is possible to modify and alter details thereof 
without departing from the spirit of the present invention.