Electronic circuit board fastening member

Details Electronic circuit board fastening member Electronic circuit board fastening member

2003-02-05

2004-08-31

Vu, Phuong T. (Department: 2841)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S740000, C361S741000, C361S747000, C361S756000, C361S801000, C361S802000, C361S807000

Reexamination Certificate

active

06785146

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electronic circuit board fastening member, particularly to a fastening member for securing an electronic circuit board, more particularly to a claw-like hook for securing an electronic circuit board.
2. Description of the Related Art
A claw-like fastening member like that shown in
FIG. 16
has been widely used to fasten an electronic circuit board. This claw-like fastening member, designated by reference numeral
100
in the drawing, is composed of a leg
104
that is elastically deformed during insertion of an electronic circuit board
102
and a projection
106
that immobilizes the electronic circuit board
102
at a prescribed location by restricting its movement in the vertical direction. Lateral movement of the electronic circuit board
102
is restricted by the leg
104
in cooperation with another such leg or a side wall.
This conventional faster
100
has a drawback, however, in the point that play will arise in the vertical direction should the thickness of the electronic circuit board
102
be smaller than the distance between a board contact surface
106
a
of the projection
106
and a mounting surface
108
(as indicated by the broken line in the drawing). Play will also arise in the lateral direction should the distance between the leg
104
and its counterpart or the side wall be larger than the width of the electronic circuit board
102
.
In order to eliminate this drawback, the dimensions of the fastening member
100
and the electronic circuit board
102
must be strictly controlled. But such strict dimensional control is disadvantageous from the cost aspect. In addition, the fastening member
100
and the electronic circuit board
102
experience repeated thermal expansion and thermal contraction when used in an environment subject to extreme temperature changes. If the fastening member
100
is designed based on the dimensions during thermal expansion, lateral and vertical play is liable to arise during thermal contraction.
On the other hand, if the design is based on the dimensions during thermal contraction, excessive stress comes to act on the fastening member
100
and the electronic circuit board
102
during thermal expansion. This may break the fastening member
100
and/or warp the electronic circuit board
102
to the point of cracking its soldering. In addition, the fastener
100
also becomes susceptible to damage under the action of heavy stress produced by vibration or the like.
SUMMARY OF THE INVENTION
An object of the present invention is therefore is to overcome the aforesaid problem by providing a fastening member for an electronic circuit board that can tolerate greater molding error than prior art fastening members and can readily cope with stress produced by volumetric variation owing to temperature change and by vibration.
In order to achieve the foregoing object, this invention in a first aspect provides a fastening member for an electronic circuit board including: an elastically deformable leg formed in a case for housing the electronic circuit board; and a projection formed continuous with the leg to be engaged with the electronic circuit board so as to fasten the electronic circuit board on a prescribed mounting surface in the case; wherein the improvement comprises: the projection is engaged with the electronic circuit board such that a prescribed angle is formed between a surface of the projection contacting the electronic circuit board, when the electronic circuit board is fastened on the mounting surface in the case.
The structure is such that when the electronic circuit board is fastened on the mounting surface, a prescribed angle is formed between the surface of the projection in contact with the electronic circuit board (board contact surface) and the electronic circuit board. Specifically, the board contact surface and the electronic circuit board form the prescribed angle and contact each other tangentially. Since the tangent between the board contact surface and the electronic circuit board is variable within the range of the board contact surface, molding error can be tolerated (absorbed) and volumetric variation produced by temperature change can be readily coped with.
In a second aspect, this invention provides a fastening member for an electronic circuit board, wherein the prescribed angle is determined based on stress acting at a time when the electronic circuit board is fastened on the mounting surface in the case.
Since the prescribed angle is defined in accordance with stress acting (on the electronic circuit board and the fastening member) at a time when the electronic circuit board is in the fastened state, such as stress produced by volumetric variation and/or vibration, the foregoing effects can be obtained to an even higher degree, making utilization possible in virtually any environment.


REFERENCES:
patent: 4692571 (1987-09-01), Trinh et al.
patent: 5452184 (1995-09-01), Scholder et al.
patent: 5973926 (1999-10-01), Sacherman et al.
patent: 6424540 (2002-07-01), Chen et al.
patent: 6445588 (2002-09-01), Masterton et al.

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