Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – Distinct contact secured to panel circuit
Reexamination Certificate
2001-01-23
2001-10-30
Ta, Tho D. (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
Distinct contact secured to panel circuit
C439S751000
Reexamination Certificate
active
06309228
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a C-shaped compliant contact composed of a connection portion adapted to be connected to an electric cable or the like, a press-fitting portion adapted to be press-fitted in a through-hole of a printed circuit board, and a contact portion adapted to be in contact with a contact of a mating connector, and more particularly to a C-shaped compliant contact capable of preventing from bending when it is being inserted into a through-hole of a printed circuit board.
A hitherto used C-shaped compliant contact will be explained by referring to
FIGS. 5
to
6
.
FIG. 5
illustrates the press-fitting portion
16
and the connection portion
18
of the C-shaped compliant contact
40
of the prior art in a partly perspective view.
FIGS. 6A
,
6
B and
6
C illustrate the C-shaped compliant contact of the prior art in a plan view, a longitudinal sectional view taken along the line A—A in
FIG. 5 and a
cross-sectional view taken along the line B—B in
FIG. 5
, respectively.
FIG. 7
illustrates the C-shaped compliant contact of the prior art in various states in one drawing from the first step to the last step for press-fitting the contact into a printed circuit board.
In general, the C-shaped compliant contact is made of a springy copper alloy such as phosphor bronze, beryllium copper or the like. It is best to manufacture the C-shaped compliant contact so as to apply uniform stresses onto the inner surface of the through-hole of a printed circuit board in which the press-fitting portion of the contact has been press-fitted.
In order to fulfil such a requirement, the applicant has proposed in Japanese Patent Application Opened No. H8-31,476 a C-shaped compliant contact
40
including a press-fitting portion
16
having an inner periphery forming a U-shaped groove having two arc portions
28
and a straight portion
30
therebetween so that the circle inscribing the U-shaped inner periphery is in an eccentric relation to the two arc portions
28
. The thickness of the arc portions
28
become progressively thinner on proceeding toward the open end of the U-shaped groove so as to make longer the length of the arc portions
28
contacting the through-hole
26
of a printed circuit board as much as possible.
With such a proposed C-shaped compliant contact
40
, because of the spring-like property of the walls of the U-shaped groove of the press-fitting portion
16
and because of the arc-shaped outer periphery to be press-fitted in the through-hole
26
, the press-fitting portion
16
elastically deforms and contacts the through-hole
26
with wide contacting surfaces, thereby achieving a uniform deformation of the printed circuit board
24
.
The C-shaped compliant contact
40
of the prior art has the press-fitting portion
16
constructed as described above and the thickness of the arc portions
28
becoming thinner on proceeding toward the ends of the walls of the U-shaped groove. When the contact
40
is being inserted into the through-hole
26
of a printed circuit board
24
, the walls of the U-shaped groove are forced toward each other as shown by arrows P and Q in
FIG. 5
so as to reduce the size of that portion to facilitate the insertion into the through-hole
26
. As a result, a force will act on the inner surface
19
in the groove
22
of the contact
40
in a direction (toward the connection portion
18
) as shown by an arrow R in
FIG. 6B
so that the connection portion
18
will be bent in the direction opposite to the outer surface
17
of the connection portion
18
, which is a problem to be solved.
As shown at the lowermost position in
FIG. 7
, the distal end of the connection portion
18
of the contact
40
is shifted by a distance of the order of
0
.
8
to
0
.
85
mm away from the extension D of the outer line of the contact
40
which has press-fitted in the through-hole
26
of the printed circuit board
24
.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a C-shaped compliant contact having a press-fitting portion which can be press-fitted in a through-hole of a printed circuit board without being bent at its connection portion adjacent the press-fitting portion.
In order to accomplish this object, in a C-shaped compliant contact composed of a connection portion to be connected to an electric cable, a connector on the rear side of a printed circuit board or the like, a press-fitting portion to be fixed in a cylindrical through-hole of the printed circuit board by press-fitting, and a contact portion to be in contact with a contact of a mating connector, said press-fitting portion formed to have an inner periphery forming a U-shaped groove in cross-section and an outer periphery having at least one arc portion in cross-section, circles inscribing said inner periphery of said U-shaped groove and circumscribing said arc portion of said outer periphery being in an eccentric relation, and the thickness of said arc portion in cross-section progressively decreasing on proceeding toward the open end of the U-shaped groove to make longer said arc portion contacting said through-hole of said printed circuit board, according to the invention said U-shaped groove is formed with a ramp surface located inside said inner periphery near to said connection portion, connected to the bottom of said U-shaped groove and inclined to make shallower said U-shaped groove.
With the C-shaped compliant contact constructed described above, however, it may be supposed that if there are differences or irregularities in diameters of through-holes caused by manufacturing errors or should a press-fitting stress more than a predetermined value be applied, the ends of the walls of the U-shaped groove of the press-fitting portion are forced toward each other in excess of the limit of their elastic deformation with resultant permanent deformation thereof. As a result, the distal ends of the walls of the U-shaped groove would separate from the inner surface of the through-hole to reduce the contacting area, resulting in unstable contact between the contact and the printed circuit board and reduction in holding force therebetween.
To overcome this problem, in a preferred embodiment of the present invention a protrusion projecting from the center of the bottom of the U-shaped groove toward its outside, which has been proposed by the applicant in Japanese Patent Application No. H10-388,374, is provided along substantially the full length of the U-shaped groove to an extent such that the protrusion does not adversely affect the flexibility of the ends of the walls of the U-shaped groove. Such a protrusion located at the bottom of the U-shaped groove of the C-shaped compliant contact effectively serves to prevent the separation of the distal ends of the walls of the U-shaped groove from the inner surface of the through-hole and the reduction in contacting area therebetween, thereby eliminating the unstable contact between the contact and the through-hole and reduction in holding force therebetween.
In another preferred embodiment, the ramp surface is: provided such that grooves on both the sides of the protrusion become progressively shallower with a decrease in size of the press-fitting portion adjacent to the connecting portion for facilitating the insertion into the through-hole.
The connected position of the ramp surface to the inner surface of the U-shaped groove at a location where the walls of the U-shaped groove close together on the side of the connection portion is preferably located between the top of the protrusion and the outer surface of the press-fitting portion of the contact. The nearer the connected position to the outer surface of the press-fitting portion of the contact, the greater will be the strength of the inner surface of the U-shaped groove on which the force tilting it acts, as a result of which the connection portion of the contact is prevented from being bent.
The C-shaped compliant contact constructed as described above according to the invention can bring about the following significant effects.
(1) A
Mashiyama Jin-ichi
Otsuki Tomonari
Takeda Yoshiaki
Baker & Botts L.L.P.
DDK Ltd.
Ta Tho D.
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