U.S. patent application number 09/871377 was filed with the patent office on 2002-08-08 for press-fit pin connection checking method and system.
Invention is credited to Fukagawa, Kazunari, Matsumoto, Hideaki, Teshima, Yasuhiro.
Application Number | 20020104683 09/871377 |
Document ID | / |
Family ID | 18895861 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020104683 |
Kind Code |
A1 |
Teshima, Yasuhiro ; et
al. |
August 8, 2002 |
PRESS-FIT PIN CONNECTION CHECKING METHOD AND SYSTEM
Abstract
A press-fit pin connection checking method using a first printed
circuit board having a plurality of through holes in which a
plurality of press-fit pins of a first press-fit connector are
adapted to be respectively press-fitted, and a checking conductor
pattern formed so as to be electrically insulated from all of the
through holes and to surround all of the through holes for
engagement with the first press-fit connector. The press-fit pin
connection checking method includes the steps of mounting the first
press-fit connector on the first printed circuit board, providing a
checking jig having a second printed circuit board and a second
press-fit connector mounted on the second printed circuit board,
engaging the second press-fit connector of the checking jig with
the first press-fit connector, and selectively connecting the
checking conductor pattern of the first printed circuit board to
output lands of the checking jig.
Inventors: |
Teshima, Yasuhiro;
(Kawasaki, JP) ; Matsumoto, Hideaki; (Kawasaki,
JP) ; Fukagawa, Kazunari; (Kawasaki, JP) |
Correspondence
Address: |
KATTEN MUCHIN ZAVIS ROSENMAN
575 MADISON AVENUE
NEW YORK
NY
10022-2585
US
|
Family ID: |
18895861 |
Appl. No.: |
09/871377 |
Filed: |
May 31, 2001 |
Current U.S.
Class: |
174/262 |
Current CPC
Class: |
G01R 31/70 20200101;
H05K 1/0268 20130101; H05K 1/116 20130101; H01R 43/205
20130101 |
Class at
Publication: |
174/262 |
International
Class: |
H05K 001/11 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2001 |
JP |
2001-031837 |
Claims
What is claimed is:
1. A printed circuit board suitable for mounting of a press-fit
connector having a plurality of press-fit pins, comprising: a
substrate; a plurality of through holes formed through said
substrate in which said press-fit pins are adapted to be
respectively press-fitted; and a checking conductor pattern formed
on an upper surface of said substrate so as to be electrically
insulated from all of said through holes and to surround all of
said through holes for engagement with said press-fit connector;
said checking conductor pattern being exposed without being covered
with a resist.
2. A printed circuit board according to claim 1, wherein the upper
surface of said substrate is exposed at a portion having a
predetermined width between each of said through holes and said
checking conductor pattern.
3. A printed circuit board according to claim 1, wherein the upper
surface of said substrate is covered with a resist at a portion
having a predetermined width between each of said through holes and
said checking conductor pattern.
4. A printed circuit board according to claim 1, further comprising
a checking output land electrically connected to said checking
conductor pattern.
5. A press-fit pin connection checking system comprising: a first
press-fit connector having a plurality of first press-fit pins; a
first printed circuit board having a first substrate, a plurality
of first through holes formed through said first substrate in which
said first press-fit pins are adapted to be respectively
press-fitted, and a first conductor pattern formed on an upper
surface of said first substrate so as to be electrically insulated
from all of said first through holes and to surround all of said
first through holes for engagement with said first press-fit
connector; a second press-fit connector having a plurality of
second press-fit pins and adapted to engage with said first
press-fit connector; a second printed circuit board having a second
substrate, a plurality of second through holes formed through said
second substrate in which said second press-fit pins are adapted to
be respectively press-fitted, a plurality of second conductor
patterns formed on said second substrate so as to be respectively
connected to said second through holes, and a plurality of output
lands respectively connected to said second conductor patterns; and
means for selectively connecting said first conductor pattern to
said output lands.
6. A press-fit pin connection checking system according to claim 5,
wherein said first conductor pattern is exposed without being
covered with a resist, and the upper surface of said first
substrate is exposed at a portion having a predetermined width
between each of said first through holes and said first conductor
pattern.
7. A press-fit pin connection checking system according to claim 5,
wherein said first conductor pattern is exposed without being
covered with a resist, and the upper surface of said first
substrate is covered with a resist at a portion having a
predetermined width between each of said first through holes and
said first conductor pattern.
8. A press-fit pin connection checking system according to claim 5,
wherein said first printed circuit board further has a checking
output land electrically connected to said first conductor
pattern.
9. A press-fit pin connection checking method comprising the steps
of: providing a first printed circuit board having a plurality of
first through holes in which a plurality of first press-fit pins of
a first press-fit connector are adapted to be respectively
press-fitted, and a first conductor pattern formed so as to be
electrically insulated from all of said first through holes and to
surround all of said first through holes for engagement with said
first press-fit connector; press-fitting said plurality of first
press-fit pins of said first press-fit connector into said
plurality of first through holes of said first printed circuit
board to thereby mount said first press-fit connector on said first
printed circuit board; providing a checking jig including a second
printed circuit board and a second press-fit connector mounted on
said second printed circuit board, said second printed circuit
board having a plurality of second through holes, a plurality of
second conductor patterns respectively connected to said second
through holes, and a plurality of output lands respectively
connected to said second conductor patterns, said second press-fit
connector having a plurality of second press-fit pins press-fitted
in said plurality of second through holes of said second printed
circuit board; engaging said second press-fit connector of said
checking jig with said first press-fit connector mounted on said
first printed circuit board; and selectively connecting said first
conductor pattern of said first printed circuit board to said
output lands of said second printed circuit board; wherein when
there is no electrical continuity between said first conductor
pattern and each of said output lands, it is determined that the
connection of said first press-fit pins and said first through
holes is acceptable, whereas when there is electrical continuity
between said first conductor pattern and each of said output lands,
it is determined that the connection of said first press-fit pins
and said first through holes is defective.
10. A press-fit pin connection checking method according to claim
9, wherein: said first printed circuit board further has a checking
output land electrically connected to said first conductor pattern;
and the selective connection of said first conductor pattern and
said output lands is provided by connecting a probe pin to said
checking output land and selectively bringing said probe pin into
contact with said output lands.
11. A press-fit pin connection checking method according to claim
9, wherein said first conductor pattern is exposed without being
covered with a resist, and a substrate of said first printed
circuit board is exposed at a portion having a predetermined width
between each of said first through holes and said first conductor
pattern.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a press-fit pin connection
checking method and system.
[0003] 2. Description of the Related Art
[0004] In recent communications equipment, high-density packaging
has proceeded in response to the demands for high performance and
multi-functionality to devices to be packaged, so that an increase
in number of printed wiring boards layered and a decrease in
bonding area and conductor spacing are remarkably proceeding. A
component mounting method is also changing from an insert mount
technology (IMT) such that a lead is inserted into a through hole
and is bonded by flow soldering to a surface mount technology (SMT)
such that a component is mounted on a surface pattern and is bonded
by reflow soldering, and the SMT is becoming mainstream. At
present, the component mounting method is in the shift from the IMT
to the SMT, and a printed circuit board (plug-in unit) using both
the technologies as mixed is most dominating.
[0005] In such a recent trend, a connector component for connecting
the printed circuit board to a back wiring board has also changed,
and the shift from an insert mount device (IMD) to a surface mount
device (SMD) as the connector component has been examined. However,
a bonding force for each pin is reduced by adopting the SMT, and
the connector component cannot endure a total pressure applied in
connecting the printed circuit board and the back wiring board. To
cope with this problem, a press-fit connector bonding technique
(gastight bonding technique) of press-fitting a press-fit pin into
a through hole has risen.
[0006] The press-fit connector bonding technique has such merits
that the bonding force for each pin is high to ensure a strong
holding force of the connector as a whole, that the flow soldering
step as a main bonding method in the IMT can be omitted, that the
shift to the SMT can be made smoothly, and that the connector is
repairable. As seen from the connection between a plug-in unit and
a back wiring board, it is considered that the press-fit connector
bonding technique will become a dominating technique in the future
connector bonding for communications equipment. However, although
the IMT is being currently shifted to the SMT, there exist many
IMDs that cannot support the SMT, and it is therefore difficult to
completely shift the IMT to the SMT in the near future.
[0007] In recent communications equipment, not only the
high-density packaging has proceeded, but also a signal
transmission speed has been increased year by year. Accordingly,
increasing a signal transmission speed between a plug-in unit (PIU)
and a back wiring board (BWB) is also proceeding. The technique
required for high-speed signal transmission includes the
suppression of transmission loss, the suppression of reflected
waves, and the unification of propagation delay. Accordingly, a
connector structure supporting high-speed signal transmission
includes a shielding structure, shortening the length of a
press-fit pin, and equalizing the lengths of differential signal
pair lines. A characteristic impedance is controlled by the
shielding structure to suppress the transmission loss. The length
of a press-fit pin is shortened to suppress the reflected waves.
The lengths of differential signal pair lines are equalized to
unify the propagation delay.
[0008] While a plug-in unit and a back wiring board are connected
by a press-fit connector in general as described above, a plurality
of press-fit pins are press-fitted into a plurality of through
holes to thereby mount the press-fit connector on the back wiring
board or the plug-in unit. Accordingly, it is necessary to check
that the press-fit pins are completely press-fitted in the through
holes. At present, whether or not the connection of the press-fit
pins and the through holes after press-fitting the press-fit pins
is acceptable is checked by only visual check for the plug-in unit
and by visual check and electrical check in combination for the
back wiring board.
[0009] FIG. 1 is a schematic sectional view for illustrating a
plug-in unit checking method in the prior art. Reference numeral 2
denotes a plug-in unit having a plurality of through holes 4, and
reference numeral 6 denotes a press-fit connector having a
plurality of press-fit pins 8. The press-fit pins 8 of the
press-fit connector 6 are press-fitted into the through holes 4 of
the plug-in unit 2 to thereby mount the press-fit connector 6 on
the plug-in unit 2. In the conventional visual checking method,
whether or not the connection of the press-fit pins 8 and the
through holes 4 is acceptable is checked by seeing the through
holes 4 from one side (back side) of the plug-in unit 2 opposite to
the press-fit connector 6 after press-fitting the press-fit pins 8
into the through holes 4 and by determining whether or not the
front ends of the press-fit pins 8 project from the back side of
the plug-in unit 2.
[0010] Referring to FIG. 2, there is shown a schematic sectional
view for illustrating a back wiring board checking method in the
prior art. Reference numeral 10 denotes a back wiring board having
a plurality of through holes 12, and reference numeral 14 denotes a
press-fit connector having a plurality of press-fit pins 16. The
press-fit pins 16 of the press-fit connector 14 are press-fitted
into the through holes 12 of the back wiring board 10 to thereby
mount the press-fit connector 14 on the back wiring board 10. The
press-fit connector 6 on the PIU side is preliminarily mounted on a
checking printed circuit board 18. The press-fit connector 6 on the
PIU side is engaged into the press-fit connector 14 on the BWB side
to thereby electrically connect the checking printed circuit board
18 to the back wiring board 10. The checking printed circuit board
18 has a plurality of conductor patterns respectively corresponding
to the press-fit pins of the press-fit connector 6 and a plurality
of output lands respectively formed at the front ends of the
conductor patterns.
[0011] In the conventional electrical checking method for the
press-fit pins 16 on the BWB side as shown in FIG. 2, two checking
printed circuit boards 18 are electrically connected to the back
wiring board 10, and the output lands of the two checking printed
circuit boards 18 are selectively connected to check the electrical
continuity, thereby determining whether or not the press-fitted
condition of the press-fit pins 16 is acceptable. The wiring in the
back wiring board 10 is complicatedly connected to a plurality of
plug-in units 2. Accordingly, to check the connection of all the
press-fit pins 16 without omission, a continuity check program is
prepared for each design of the back wiring board 10 and the
plug-in units 2 in combination, and the continuity check is
performed in accordance with this program. The visual check for the
back wiring board 10 is similar to that for the plug-in unit 2 as
mentioned above with reference to FIG. 1. That is, whether or not
the connection of the press-fit pins 16 and the through holes 12 is
acceptable is checked by determining whether or not the front ends
of the press-fit pins 16 project from the back side of the back
wiring board 10.
[0012] FIGS. 3A to 3C are sectional views showing an acceptable
mode and a defective mode. More specifically, FIG. 3A shows an
acceptable mode, and FIGS. 3B and 3C show defective modes. The
defective modes shown in FIGS. 3B and 3C can be detected by the
visual check. However, the defective mode shown in FIG. 3C cannot
be detected by the electrical check, because the press-fit pin 16
is in electrical continuity to the through hole 12.
[0013] Although the visual check is low in efficiency and detection
power to defective connection, all kinds of buckling of the
press-fit pin 16 as shown in FIGS. 3B and 3C can be detected as
detectable defective modes by the visual check. On the other hand,
although the electrical check is high in efficiency, only the
complete buckling of the press-fit pin 16 as shown in FIG. 3B such
that the press-fit pin 16 is not in contact with the through hole
12 can be detected as a detectable defective mode by the electrical
check, and another kind of buckling of the press-fit pin 16 as
shown in FIG. 3C such that the press-fit pin 16 is in contact with
the through hole 12 cannot be detected as a defective mode by the
electrical check.
[0014] In the conventional press-fit pin connection checking
method, only the visual check is performed for the plug-in unit, so
that the omission of detection of defectives is prone to occur.
Also in the connection check for the press-fit pins on the BWB
side, the defective mode shown in FIG. 3C can be detected only by
the visual check, so that there is a possibility of omission of
detection of defectives. In the case that the omission of detection
of defectives occurs, the defectives omitted may be detected in
subsequent function check or the like. However, a large number of
man-hours are needed to seek real defectives.
[0015] Further, the conventional connection checking method
requires a dedicated jig (including a checking printed circuit
board on the PIU side, testing device, and program) for the
electrical check for the back wiring board in each product, so that
a cost and time for preparation of the connection check are
required. Moreover, the visual check for detection of defectives is
important in the conventional connection checking method, so that
the length of each press-fit pin must be larger than the thickness
of a substrate, so as to ensure the detection power. However, a
reduction in length of each press-fit pin of a press-fit connector
supporting high-speed signal transmission is now being pursued, and
it is becoming general that the length of each press-fit pin is
smaller than the thickness of the substrate. In this case, the
front end of each press-fit pin does not project from the back
surface of the substrate, and the visual check cannot therefore be
performed.
SUMMARY OF THE INVENTION
[0016] It is therefore an object of the present invention to
provide a press-fit pin connection checking method and system which
can detect defective press-fit of all the press-fit pins by only
electrical check.
[0017] It is another object of the present invention to provide a
press-fit pin connection checking method and system which can
detect defective press-fit of each press-fit pin even in the case
that the length of each press-fit pin is smaller than the thickness
of the substrate.
[0018] It is a further object of the present invention to provide a
printed circuit board structure required for realization of such a
press-fit pin connection checking method.
[0019] In accordance with an aspect of the present invention, there
is provided a printed circuit board suitable for mounting of a
press-fit connector having a plurality of press-fit pins,
comprising a substrate; a plurality of through holes formed through
said substrate in which said press-fit pins are adapted to be
respectively press-fitted; and a checking conductor pattern formed
on an upper surface of said substrate so as to be electrically
insulated from all of said through holes and to surround all of
said through holes for engagement with said press-fit connector;
said checking conductor pattern being exposed without being covered
with a resist.
[0020] Preferably, the upper surface of said substrate is exposed
at a portion having a predetermined width between each of said
through holes and said checking conductor pattern. Alternatively,
the upper surface of said substrate may be covered with a resist at
a portion having a predetermined width between each of said through
holes and said checking conductor pattern. Preferably, the printed
circuit board further comprises a checking output land electrically
connected to said checking conductor pattern.
[0021] In accordance with another aspect of the present invention,
there is provided a press-fit pin connection checking system
comprising a first press-fit connector having a plurality of first
press-fit pins; a first printed circuit board having a first
substrate, a plurality of first through holes formed through said
first substrate in which said first press-fit pins are adapted to
be respectively press-fitted, and a first conductor pattern formed
on an upper surface of said first substrate so as to be
electrically insulated from all of said first through holes and to
surround all of said first through holes for engagement with said
first press-fit connector; a second press-fit connector having a
plurality of second press-fit pins and adapted to engage with said
first press-fit connector; a second printed circuit board having a
second substrate, a plurality of second through holes formed
through said second substrate in which said second press-fit pins
are adapted to be respectively press-fitted, a plurality of second
conductor patterns formed on said second substrate so as to be
respectively connected to said second through holes, and a
plurality of output lands respectively connected to said second
conductor patterns; and means for selectively connecting said first
conductor pattern to said output lands.
[0022] In accordance with a further aspect of the present
invention, there is provided a press-fit pin connection checking
method comprising the steps of providing a first printed circuit
board having a plurality of first through holes in which a
plurality of first press-fit pins of a first press-fit connector
are adapted to be respectively press-fitted, and a first conductor
pattern formed so as to be electrically insulated from all of said
first through holes and to surround all of said first through holes
for engagement with said first press-fit connector; press-fitting
said plurality of first press-fit pins of said first press-fit
connector into said plurality of first through holes of said first
printed circuit board to thereby mount said first press-fit
connector on said first printed circuit board; providing a checking
jig including a second printed circuit board and a second press-fit
connector mounted on said second printed circuit board, said second
printed circuit board having a plurality of second through holes, a
plurality of second conductor patterns respectively connected to
said second through holes, and a plurality of output lands
respectively connected to said second conductor patterns, said
second press-fit connector having a plurality of second press-fit
pins press-fitted in said plurality of second through holes of said
second printed circuit board; engaging said second press-fit
connector of said checking jig with said first press-fit connector
mounted on said first printed circuit board; and selectively
connecting said first conductor pattern of said first printed
circuit board to said output lands of said second printed circuit
board; wherein when there is no electrical continuity between said
first conductor pattern and each of said output lands, it is
determined that the connection of said first press-fit pins and
said first through holes is acceptable, whereas when there is
electrical continuity between said first conductor pattern and each
of said output lands, it is determined that the connection of said
first press-fit pins and said first through holes is defective.
[0023] Preferably, said first printed circuit board further has a
checking output land electrically connected to said first conductor
pattern; and the selective connection of said first conductor
pattern and said output lands is provided by connecting a probe pin
to said checking output land and selectively bringing said probe
pin into contact with said output lands. The detection of no
electrical continuity indicates an acceptable mode, and the
detection of electrical continuity indicates a defective mode.
[0024] The above and other objects, features and advantages of the
present invention and the manner of realizing them will become more
apparent, and the invention itself will best be understood from a
study of the following description and appended claims with
reference to the attached drawings showing some preferred
embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a schematic sectional view for illustrating a
plug-in unit checking method in the prior art;
[0026] FIG. 2 is a schematic sectional view for illustrating a back
wiring board checking method in the prior art;
[0027] FIG. 3A is a sectional view showing an acceptable mode;
[0028] FIGS. 3B and 3C are sectional views showing defective
modes;
[0029] FIG. 4 is a partially cutaway plan view of a printed circuit
board according to a preferred embodiment of the present
invention;
[0030] FIG. 5 is a cross section taken along the line 5-5 in FIG.
4;
[0031] FIG. 6A is a perspective view showing a through hole and a
conductor pattern according to the preferred embodiment;
[0032] FIG. 6B is a view similar to FIG. 6A, showing another
preferred embodiment of the present invention;
[0033] FIGS. 7A to 7C are perspective views showing the steps of a
connection checking method for press-fit pins on the BWB side;
[0034] FIG. 8 is a perspective view showing the step of the
connection checking method subsequent to the step of FIG. 7C;
[0035] FIG. 9 is a sectional view showing the connection checking
method shown in FIG. 8;
[0036] FIG. 10 is a sectional view showing a connection checking
method for press-fit pins on the PIU side;
[0037] FIG. 11 is a sectional view for illustrating the principle
of acceptable/defective determination in the present invention;
and
[0038] FIG. 12 is a schematic diagram of a check circuit in the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] Referring to FIG. 4, there is shown a partially cutaway plan
view of a printed circuit board 20 such as a back wiring board
according to a preferred embodiment of the present invention. FIG.
5 is a cross section taken along the line 5-5 in FIG. 4. The
printed circuit board 20 is applicable also to a plug-in unit. In
the following description, the printed circuit board 20 is assumed
to be a back wiring board. The back wiring board 20 includes a
substrate 22, a plurality of through holes 24 formed through the
substrate 24 in which a plurality of press-fit pins of a press-fit
connector are adapted to be respectively press-fitted, and a
checking conductor pattern 26 formed on an upper surface 22a of the
substrate 22 so as to be electrically insulated from all the
through holes 24 and to surround all the through holes 24 for
engagement with the press-fit connector.
[0040] In general, the press-fit connector has a rectangular
connection surface, so that the checking conductor pattern 26 is
also rectangular. The checking conductor pattern 26 is formed from
a copper pattern, for example. The upper surface 22a of the
substrate 22 is exposed at a portion 28 having a predetermined
width between each through hole 24 and the checking conductor
pattern 26. Alternatively, each portion 28 may be covered with a
resist. Reference numeral 30 denotes a checking output land
electrically connected to the checking conductor pattern 26. As
shown in FIG. 5, the inner wall of each through hole 24 is plated
with copper, and it is in electrical continuity with an inner layer
32 formed from a copper foil. The periphery of the checking output
land 30 and the back surface of the back wiring board 20 are
covered with a resist 34. However, the checking conductor pattern
26 is exposed without being covered with a resist.
[0041] FIG. 6A is a schematic perspective view showing one of the
through holes 24 and a part of the checking conductor pattern 26
surrounding the through hole 24. Each through hole 24 is of a type
having no land, and it is a drilled hole having a diameter of 0.65
mm. For example, the part of the checking conductor pattern 26
surrounding the through hole 24 has a circular opening having a
diameter of 0.95 mm. FIG. 6B is a schematic perspective view
showing a through hole 24' of a type having a land 36 and a
checking conductor pattern 26' surrounding the through hole 24'.
The land 36 of the through hole 24' has an outer diameter of 0.9
mm. Since the through hole 24' has the land 36, the checking
conductor pattern 26' surrounding the through hole 24' has a
circular opening having a diameter of 1.2 mm, which is larger than
the circular opening of the checking conductor pattern 26 shown in
FIG. 6A. The present invention is applicable both to a printed
circuit board having the through holes of the type shown in FIG. 6A
and to a printed circuit board having the through holes of the type
shown in FIG. 6B.
[0042] FIGS. 7A to 7C show the steps of a connection checking
method for press-fit pins on the BWB side. Referring to FIG. 7A,
reference numeral 39 denotes a checking PIU jig composed of a
checking printed circuit board 40 and a press-fit connector 38
mounted on the checking printed circuit board 40. The checking
printed circuit board 40 has a plurality of conductor patterns 42
respectively connected to a plurality of press-fit pins (not shown)
of the press-fit connector 38, and a plurality of output lands 44
respectively formed at the upper ends (front ends) of the conductor
patterns 42. Reference numeral 14 denotes a press-fit connector on
the BWB side. The press-fit connector 14 has a plurality of
press-fit pins 16' each having a relatively small length. It is
assumed that the connection between the conductor patterns 42 of
the printed circuit board 40 and the press-fit pins of the
press-fit connector 38 in the checking PIU jig 39 is preliminarily
checked to be complete.
[0043] As shown in FIG. 7B, the press-fit pins 16' are press-fitted
into the through holes 24 of the back wiring board 20 as shown by
an arrow 46 to thereby mount the press-fit connector 14 on the back
wiring board 20. Thereafter, the press-fit connector 38 of the
checking PIU jig 39 is engaged into the press-fit connector 14 on
the BWB side as shown by an arrow 48 in FIG. 7C. As a result, the
checking PIU jig 39 is electrically connected to the back wiring
board 20. Thereafter, the output land 30 of the checking conductor
pattern 26 is selectively and sequentially connected to the output
lands 40 of the checking PIU jig 39 as shown by a broken line 50 in
FIG. 8, thereby checking a connected condition of each press-fit
pin 16' of the press-fit connector 14 to the corresponding through
hole 24 of the checking conductor pattern 26 of the back wiring
board 20.
[0044] The selective and sequential connection of the output land
30 of the checking conductor pattern 26 to the output lands 44 of
the checking PIU jig 39 may be made by connecting a probe pin to
the output land 30 of the checking conductor pattern 26 and
sequentially bringing this probe pin into contact with the output
lands 44 of the checking PIU jig 39, for example. In this
connection check, the detection of no electrical continuity
indicates an acceptable mode, and the detection of electrical
continuity indicates a defective mode, because any one of the
press-fit pins 16' is in contact with the checking conductor
pattern 26.
[0045] FIG. 9 is a sectional view showing a connection checking
method for the press-fit pins on the BWB side. In this method, two
checking PIU jigs 39 are mounted on the back wiring board 20. One
of the two PIU jigs 39 is fitted with a press-fit connector 14
having a plurality of relatively long press-fit pins 16, and the
other PIU jig 39 is fitted with a press-fit connector 14' having a
plurality of relatively short press-fit pins 16'. The front ends of
the relatively long press-fit pins 16 project from the back surface
of the back wiring board 20, and the front ends of the relatively
short press-fit pins 16' retract from the back surface of the back
wiring board 20. Thus, the present invention is applicable to the
connection check for both types of press-fit pins. The continuity
check may be made by connecting a probe pin to the output land 30
of the checking conductor pattern 26 and sequentially bringing this
probe pin into contact with the output lands 44 of the checking PIU
jig 39.
[0046] Referring to FIG. 10, there is shown a schematic sectional
view showing a connection checking method for the press-fit pins on
the PIU side. Reference numeral 51 denotes a checking BWB jig. The
checking BWB jig 51 includes a checking printed circuit board 52
and a press-fit connector 54 mounted on the printed circuit board
52 and having a plurality of press-fit pins (not shown). The
checking printed circuit board 52 has a plurality of conductor
patterns (not shown) respectively connected to the press-fit pins
of the press-fit connector 54 and a plurality of output lands (not
shown) respectively formed at the front ends of the conductor
patterns. It is assumed that the connection of the press-fit
connector 54 and the checking printed circuit board 52 is
preliminarily checked to be complete.
[0047] Reference numeral 56 denotes a plug-in unit. The plug-in
unit 56 has a plurality of through holes 58, a checking conductor
pattern similar to the conductor pattern 26 shown in FIG. 4, and a
checking output land similar to the output land 30 shown in FIG. 4.
Reference numeral 6 denotes a press-fit connector having a
plurality of press-fit pins 8'. The press-fit pins 81 of the
press-fit connector 6 are press-fitted into the through holes 58 of
the plug-in unit 56 to thereby mount the press-fit connector 6 on
the plug-in unit 56. Thereafter, the press-fit connector 6 is
engaged into the press-fit connector 54 of the checking BWB jig 51
to thereby electrically connect the plug-in unit 56 to the checking
BWB jig 51.
[0048] The continuity check for the press-fit pins 8' may be made
by connecting a probe pin to the checking output land of the
plug-in unit 56 and sequentially bringing this probe pin into
contact with the output lands of the checking BWB jig 51. In this
continuity check, the detection of no electrical continuity
indicates an acceptable mode, and the detection of electrical
continuity indicates a defective mode. FIG. 11 is a sectional view
for illustrating the principle of acceptable/defective
determination in the present invention. In FIG. 11, (A) and (C)
indicate the case of no electrical continuity=acceptable mode, and
(B) and (D) indicate the case of electrical continuity=defective
mode.
[0049] FIG. 12 is a schematic diagram of a check circuit in the
present invention. The back wiring board 20 and the checking
printed circuit board 40 are connected by the plural press-fit pins
16'. The checking output land 30 of the back wiring board 20 and
the output lands 44 of the checking printed circuit board 40 are
selectively and sequentially connected by a checking device 60
having a continuity check circuit 62 to perform the connection
check for the press-fit pins 16'. In the case that the connection
of any one of the press-fit pins 16' is defective, a switch becomes
on as shown by an arrow 64 to detect the electrical continuity.
[0050] According to the present invention as described above, even
in the case that the length of each press-fit pin is smaller than
the thickness of the substrate, defective press-fit of each
press-fit pin can be detected by electrical check only. Further, it
is sufficient that a checking jig be prepared according to the type
of a press-fit connector. Accordingly, the checking jig for
electrical check can be simplified and the cost and time for
electrical check can be reduced. Further, no visual check is needed
and it is therefore possible to prevent the omission of detection
of any defective connection.
[0051] The present invention is not limited to the details of the
above described preferred embodiments. The scope of the invention
is defined by the appended claims and all changes and modifications
as fall within the equivalence of the scope of the claims are
therefore to be embraced by the invention.
* * * * *