Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1999-11-16
2001-12-25
Gaffin, Jeffrey (Department: 2841)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S261000, C174S263000, C174S265000, C361S791000, C361S792000, C361S803000
Reexamination Certificate
active
06333471
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a technique for manufacturing a double-sided printed circuit board for use in electronic equipment, especially to a technique for improving the construction of a sheet metal component for double pattern conduction to be used in the manufacture of a printed circuit board.
DESCRIPTION OF THE BACKGROUND ART
FIG. 3
is a perspective view of a publicly-unknown conventional sheet metal component
9
for double pattern conduction (hereinafter referred to as a conventional sheet metal component) which is used to establish connection between patterns on both sides of a printed circuit board.
FIG. 4
is a longitudinal cross-sectional view of the component
9
mounted on a printed circuit board.
In
FIGS. 3 and 4
, the reference
1
designates a printed circuit board (PCB);
1
a
designates a base material;
2
designates solder;
3
designates a solder resist;
4
designates an A-plane pattern of the PCB
1
;
5
designates a B-plane pattern of the PCB
1
;
6
designates a through hole in the PCB
1
;
7
designates cream solder;
9
c
designates a ceiling portion of the conventional sheet metal component
9
;
9
b
designates a surface portion to be soldered which is bent inwardly from the end of the ceiling portion
9
c
so as to form a bend R
1
and further extends to face the ceiling portion
9
c;
and
9
a
designates a lead portion which protrudes downwardly from the surface portion
9
b.
Now the action of the sheet metal component
9
will be described.
As a way for establishing connection between patterns on both sides of a printed circuit board which forms a predetermined circuit, there have been proposed methods of (1) plating through holes with copper; (2) filling through holes with silver pastes for hardening; (3) inserting and caulking eyelets for soldering; and (4) inserting jumpers for soldering; however, each method has a problem. In the prior art methods (1) and (2), a substrate becomes costly because of the necessity of processing on the substrate. The methods (3) and (4), on the other hand, are free from such a cost problem, but thermal expansion or contraction of the PCB due to environmental temperature changes during device operation tends to cause stress cracking at solder joints.
The method of manufacturing a printed circuit board shown in
FIGS. 3 and 4
is devised to resolve such problems simultaneously.
First, the cream solder
7
is printed on the A-plane pattern
4
of the printed circuit board
1
by a cream-solder printing machine. Then, the sheet metal component
9
for double pattern conduction in
FIG. 3
is mounted on the cream solder
7
by general-purpose surface-mount-component placement equipment. At this time, the lead portions
9
a
of the conventional sheet metal component
9
are inserted into the through hole
6
in the printed circuit board
1
, and their respective end portions slightly protrude from the B plane. During the same process, other surface-mount electronic components are also mounted on corresponding patterns.
The surface portions
9
b
of the conventional sheet metal component
9
on the side of the A plane are then soldered to the A-plane pattern
4
by melting the cream solder
7
using a reflow device. The mounting described so far is feasible with a series of surface-mount line processes which would not increase in complexity. Besides, the use of the surface-mount-component placement equipment for mounting prevents scattering of unmolten cream solder
7
.
Next, through-hole-mount components are inserted into corresponding through holes. Then, the through-hole-mount components and the end portions of the respective lead portions
9
a
which protrude from the conventional sheet metal component
9
are soldered to the B-plane pattern
5
by a flow soldering device. At this time, capillary action of solder causes solder wicking in between the two opposing lead portions
9
a
of the conventional sheet metal component
9
, resulting in an increase in the volume of the lead portions
9
a
by the amount of solder wicking. Thus, the allowed value for current slightly increases.
When this printed circuit board
1
is integrated into electronic equipment, the base material
1
a
of the printed circuit board
1
undergoes continuous temperature changes due to environmental temperature changes in starting or stopping the electronic equipment; consequently, stress such as contraction occurs in the material
1
a,
causing a problem of cracking of solder at the solder joints. The conventional sheet metal component
9
in
FIG. 3
, however, can prevent such occurrence of cracking of solder because it can distribute the stress at its bends R
1
.
As above described, the conventional sheet metal component
9
with the construction in
FIG. 3
achieves several effects: high packing density, low cost, and the prevention of cracking of solder. The component
9
, however, may be mounted nearly in close contact with the printed circuit board
1
as shown in FIG.
4
and it may fail to completely distribute the stress at its bends R
1
because of high rigidity of the bends R
1
due to large ceiling and surface areas
9
c,
9
b.
Further, a distance between the solder joints on the A, B planes may be relatively short from a viewpoint of stress distribution. Therefore, the conventional sheet metal component
9
still carries a problem of the impracticability of completely distributing the stress.
For these reasons, even if both patterns are brought into conduction with the conventional sheet metal component
9
in
FIG. 3
, there remains not a small probability that stress will be focused on a portion between the solder joints and thereby cause cracking of solder at the joints.
SUMMARY OF THE INVENTION
A first aspect of the present invention is directed to a sheet metal component for double pattern conduction, for establishing connection between a first plane pattern and a second plane pattern provided on first and second planes of a printed circuit board, respectively. The sheet metal component comprises: a lead portion; a coupling portion; a ceiling portion having a first portion and a second portion connected to the first portion; and a portion to be soldered, having a surface to be soldered which is parallel to the first plane and an end portion that can be soldered to the first plane pattern through the surface to be soldered, wherein the lead portion, the coupling portion, the ceiling portion, and the portion to be soldered are integrated; the lead portion is shaped and sized to be inserted into a through hole passing through the printed circuit board, with its end portion protruding from the second plane; the end portion of the lead portion is made of a material that can be soldered to the second plane pattern after the lead portion is inserted into the through hole; the lead portion is connected to the first portion of the ceiling portion by the coupling portion that is bent inwardly in the middle to form a first bend; the portion to be soldered is bent inwardly from an end portion of the second portion of the ceiling portion to form a second bend and further extends to face the second portion; and a height from the ceiling portion to the portion to be soldered is greater than a height from the ceiling portion to the coupling portion.
According to a second aspect of the present invention, in the sheet metal component for double pattern conduction according to the first aspect, the first portion is located in the center of the ceiling portion; the second portion corresponds to one side portion of the ceiling portion which extends longitudinally beyond the first portion; and a width of the end portion of the portion to be soldered is equivalent to a width of the second portion.
A third aspect of the present invention is directed to a printed circuit board comprising: a base material; a first plane pattern provided on a first plane of the base material; a second plane pattern provided on a second plane of the base material; a through hole passing through the first plane pattern, the b
Birch & Stewart Kolasch & Birch, LLP
Gaffin Jeffrey
Mitsubishi Denki & Kabushiki Kaisha
Patel I B
LandOfFree
Sheet metal component for double pattern conduction and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sheet metal component for double pattern conduction and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sheet metal component for double pattern conduction and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2597417