Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – Distinct contact secured to panel circuit
Reexamination Certificate
1999-09-20
2001-12-04
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
06325643
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an improvement of a press-in contact composed of a connection portion to be connected to an electric cable, a circuit of a board or the like, a contact portion to contact a contact of a mating connector, and a press-fitting portion adapted to be fitted in a through-hole of a printed circuit board by press-fitting in a manner eliminating any damage to the press-in contact and the plated through-hole of the printed circuit board, which would otherwise occur.
Hitherto used press-in contacts of this kind are generally made of phosphor bronze or beryllium copper. It is ideal to construct a press-in contact so as to uniformly distribute the stresses on the inner wall of a cylindrical through-hole of a printed circuit board when the press-in contact has been fitted in the through-hole by press-fitting. For this purpose, the press-in contact disclosed in Japanese Patent Application Opened No. H7-245131 includes the press-fit pin having a press-fitting portion which is elastically deformable in its cross-section and adapted to be fitted in a through-hole of a printed circuit board by press-fitting. This press-fitting portion is characterized to have a V-shaped cross-section.
Moreover, Japanese Patent Application No. 186,273/94 filed on Jul. 15, 1994, with Opened No. H8-31476 corresponding to U.S. Pat. No. 5,667,412 filed by the assignee of this application discloses the press-in contact having a press-fitting portion whose inner periphery forms a U-shape groove and outer periphery consists of two arc portions and a straight portion. The straight portion is located between the two arc portions. Circles inscribing the inner periphery and circumscribing the outer periphery are in an eccentric relation and the thickness of walls of the two arc portions becomes progressively thinner toward the open end of the U-shaped groove to provide longer outer peripheries contacting a through-hole.
With the former press-in contact of the prior art, on fitting it in a through-hole of a printed circuit board, the ends of the V- or U-shaped press-fitting portion at its open end have a springiness so as to be resiliently deformed easily, particularly, stepwise deformed at respective parts in accordance with irregularity in diameter of through holes. With the latter press-in contact of the prior art, as the parts of the contact to be press-fitted in a printed circuit board are circular arcs, the area contacting a through-hole becomes larger so that the printed circuit board is uniformly deformed.
With these known press-in contacts, however, due to the irregularities in diameter of through-holes and press-fitting stresses in excess of predetermined values, the distal ends of walls forming the U-shaped cross-section at its open end often tend to deform inwardly toward each other beyond the elastic limit and set in the excess deformation. As a result, the distal ends would separate from the inner wall of the through-hole to reduce the contacting area, resulting in unstable contact between the press-in contact and the printed circuit board and reduction in holding force therebetween.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved press-in contact which eliminates all the disadvantages of the press-in contacts of the prior art described above to provide stable holding force and stable contact between the press-in contact and a printed circuit board.
In order to accomplish this object, in press-in contact composed of a connection portion to be connected to an electric cable, a circuit of a board or the like, a press-fitting portion to be fixed in a cylindrical through-hole of a printed circuit board by press-fitting, and a contact portion to contact against a contact of a mating connector, said press-fitting portion formed to have an inner periphery forming a U-shaped groove and an outer periphery having two arc portions and a straight portion between the two arc portions, and circles inscribing the inner periphery of said U-shaped groove and circumscribing the outer periphery being in an eccentric relation, the thickness of walls of said two arc portions becoming progressively thinner toward the open end of the U-shaped groove to make longer said arc portions contacting said through hole, according to the invention a protrusion projecting from the center of the bottom of said U-shaped groove is provided along the full length of said U-shaped groove to an extent such that the protrusion does not adversely affect the flexibility of the ends of the walls of said two arc portions at the open end of the U-shaped groove.
When a press-in contact is being fitted in a through-hole of a printed circuit board by press-fitting, ends of the press-fitting portion of the press-in contact at the open end of the U-shaped cross-section tend to deform inwardly. With the press-in contact thus constructed according to the invention, however, internal stresses will occur in the protrusion located at the bottom of the U-shaped groove, so that the internal stresses oppose the bending of the ends of the press-fitting portion and prevent the plastic deformation of the distal ends as much as possible. Therefore, the press-in contact according to the invention gives the uniform deformation to the inner wall surface of the through-hole of the printed circuit board, as a result of which the contact between the press-in contact and the through-hole is maintained in a stable condition.
As the ends of the walls forming the U-shaped groove of the press-fitting portion of the press-in contact according to the invention have the springiness likely to deform, and the press-fitting portion has the arc portions, the amount of deformation of the printed circuit board can be uniformly distributed. Therefore, stresses acting upon the board are uniformly distributed, so that even if an interference is somewhat large, no whitening occurs in the board and sufficient holding force can be maintained without any reduction of dielectric strength and disconnection in circuits.
The existence of the protrusion according to the invention, moreover, can prevent any plastic-deformation of the ends of the walls forming the U-shaped groove beyond the elastic limit and hence prevent any loss of springiness due to such an excess deformation. In this manner, the protrusion according to the invention can prevent the ends of the press-fitting portion from separating from the inner wall of the through-hole to reduce the contacting area between the press-in contact and the printed circuit board, and hence can prevent the unstable contact therebetween and reduction in holding force against the board.
The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings.
REFERENCES:
patent: 5667412 (1997-09-01), Takahaski et al.
patent: 5738550 (1998-04-01), Sakuraoka et al.
patent: 5796588 (1998-08-01), Machida et al.
patent: 5944563 (1999-08-01), Nagafuji
patent: 8031476 (1994-07-01), None
patent: 07245131 (1995-09-01), None
Mashiyama Jin-ichi
Ohtsuki Tomonari
Baker & Botts LLP
DDK Ltd.
McCamey Ann
Ta Tho D.
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