Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – Distinct contact secured to panel circuit
Reexamination Certificate
1999-11-16
2001-04-03
Bradley, Paula (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
Distinct contact secured to panel circuit
C439S078000, C439S876000
Reexamination Certificate
active
06210181
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to press-fit terminals for use in circuit boards, etc. and electrical connectors having such a terminal.
2. Description of the Related Art
Japanese UM patent application Kokoku No. 3-14782 discloses such a press-fit terminal.
As shown in
FIG. 6
, this press-fit terminal comprises a pin-like metallic terminal body
51
and a metallic sleeve
52
provided with a flange. The terminal body
51
has a square cross-section and has a press-fit section tapered toward the tip. The metallic sleeve
52
is put over the press-fit section.
In use, when the press-fit terminal is press-fitted into a through-hole which is provided in a circuit board P and lined with a conductive layer P
1
, the metallic sleeve
52
engages the circuit board P with the flange, and only the terminal body
51
is press-fitted. As the terminal body
51
is press-fitted, the tapered square press-fit section broadens the metallic sleeve
52
with the edges. Consequently, the terminal body
51
is connected electrically under the contact pressure to the conductive layer P
1
of the circuit board P via the metallic sleeve
52
.
However, such a conventional press-fit terminal has the following drawbacks:
(1) The metallic sleeve lacks a spring property. The metallic sleeve has a closed annular shape and lacks a spring property so that when the terminal body is press-fitted, satisfactory amounts of expansion are not provided, resulting in the low contact pressure between the metallic sleeve and the conductive layer.
(2) Amounts of expansion of the metallic sleeve tend to be different. The expansion of the metallic sleeve is made by the press-fit of the tapered press-fit section into the metallic sleeve. Consequently, if the length of press-fit (the distance traveled by the terminal body) is constant, manufacturing errors in the radial direction of respective members produce different amounts of sleeve expansion and thus different contact pressures. Consequently, when a plurality of press-fit terminals are press-fitted by the same length of press-fit, there are different contact pressures among the press-fit terminals. If an attempt is made to make the contact pressure constant, then the length of press-fit varies. In addition, since the degree of taper is small, the length of press-fit is large.
(3) A precise finish is required. If an attempt is made to keep the contact pressure within a predetermined range under a constant length of press-fit, high precision work is necessary for the inside diameter of the conductive layer, the inside and outside diameters of the metallic sleeve, and the outside diameter of the press-fit section.
(4) The press-fit terminal is prone to coming out. Since the terminal body is tapered, it tends to come out in the direction. If the degree of taper is reduced to minimize the coming out, then the length of press-fit is too large to be practical.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a press-fit terminal able to produce a satisfactory contact pressure by a small length of press-fit and an electrical connector having such a press-fit terminal.
A press-fit terminal relative to the invention is press-fitted in the through-hole of a circuit board and brought into contact with a conductive section of the through-hole.
According to the invention the press-fit terminal comprises a pin-like terminal body and a spring contact element attached around the terminal body. The terminal body has a support section at a middle portion in the longitudinal direction for supporting the spring contact element. The spring contact element has a tubular form with at least one opening groove extending in the longitudinal direction to make the spring contact element flexible at the radial direction. It has an outer contact portion at an utmost outer position in the radial direction and inner contact portions at an utmost inner position in the radial direction. The outer contact portion normally lies outside of the diameter of the conductive section of the through-hole.
When the press-fit terminal is press-fitted in the conductive section, however, the spring contact element is compressed to bring the outer and inner contact portions into resilient contact with the conductive section and the support section, respectively.
According to one aspect of the invention, the support section has a stepped-down tubular form with shoulders at opposite ends, and the spring contact element has the maximum diameter at the central position in the axial direction as the outer contact portion and the minimum diameter at the opposite ends as the inner contact portions which engage the shoulders to control axial movement of the spring contact element so that the outer contact portion makes contact with the conductive section in a large area and the terminal is fixed in the through-hole by the spring contact element which engages the shoulders.
According to another aspect of the invention, the spring contact element has at least one of a boss at a middle portion in the axial direction and a ridge extending in the axial direction as the outer contact portion and the minimum diameter at opposite ends as the inner contact portions which engage the shoulders to control axial movement of the spring contact element. Consequently, the press-fit terminal is easy to press-fit and in contact with the conductive section of the through-hole in a large area in the longitudinal direction to prevent tilt of the terminal. The outer contact portion has a gentle slope in the press-fit direction and a steep slope in the removal direction so that it is easy to press-fit but difficult to remove.
Such press-fit terminals are mounted in a housing to provide an electrical connector. The housing has a control face which abuts on the circuit board to control the depth of press-fitting of the terminal into the through-hole so that the quantity of press-fitting is determined automatically to provide a constant contact pressure.
REFERENCES:
patent: 4076356 (1978-02-01), Tamburro
patent: 4684203 (1987-08-01), Bihler
patent: 4735575 (1988-04-01), Shaffer
patent: 3120629 (1982-12-01), None
patent: 405144490 (1982-06-01), None
patent: 3-14782 (1991-04-01), None
patent: 7413113 (1976-04-01), None
patent: 7505494 (1976-11-01), None
Bradley Paula
Hirose Electric., Ltd.
Kanesaka & Takeuchi
Ta Tho D.
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