Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1998-09-10
2001-08-28
Paladini, Albert W. (Department: 2841)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S268000, C228S180210, C361S803000, C439S059000
Reexamination Certificate
active
06281449
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a printed board to be mounted with electronic components, and a method for making the printed board. The present invention also relates to a connecting arrangement of a conductive element to the printed board.
BACKGROUND ART
A printed board
1
shown in
FIG. 9 and a
printed board
1
′ shown in
FIG. 10
are both publicly well known. The printed board shown in
FIG. 9
comprises a substrate
10
made of an insulating material, a predetermined wiring pattern (not illustrated) formed on a surface of the substrate, and a metal terminal
11
made of a thin plate of nickel for example. The metal terminal
11
has end potions
11
A,
11
B spaced longitudinally from each other. The metal terminal
11
is fixed to the substrate
10
by solder (A) only at the end portion
11
A. The end portion
11
B is not directly supported by the substrate
10
.
Likewise, the printed board
1
′ shown in
FIG. 10
comprises a substrate
10
′ made of an insulating material, a predetermined wiring pattern (not illustrated) formed on a surface of the substrate, and a metal terminal
11
′ made of a thin plate of nickel for example. Differing from the metal terminal
11
in
FIG. 9
, the metal terminal
11
′ in
FIG. 10
has its entire back face fixed to the substrate
10
′ by solder (A′).
Each of the metal terminals
11
,
11
′ is attached with another conductive element (
12
,
12
′) made of metal for establishing electrical connection with an external circuit (see
FIGS. 13
,
14
.) Through this additional conductive element, electric components mounted on the printed boards
1
,
1
′ can be supplied with drive voltage for example.
The substrates
10
,
10
′ can be respectively connected to the metal terminals
11
,
11
′ by means of re-flow soldering. There is a problem, however, according to this method. Specifically, the arrangement of the printed board shown in
FIG. 9
does not render self-alignment of the metal terminal
11
to the substrate
10
. As a result, positioning accuracy of the metal terminal
11
is not very good.
The term self-alignment in the re-flow soldering as used herein may be described as follows: Referring now to
FIG. 11
, a piece of metal
30
is to be fixed to a printed board by re-flow soldering. As shown in the figure, the metal piece
30
is an oblong strip of metal, with two end portions
30
a,
30
b
apart longitudinally from each other. The printed board is formed with deposits of solder
35
at predetermined locations respectively corresponding to the two end portions
30
a,
30
b.
Then the metal piece
30
is lowered on the printed board so that the two end portions
30
a,
30
b
will locate at respective predetermined regions, contacting the deposits of solder. Under this state, the solder
35
is heated to melt, and then cooled to solidify, completing the re-flow soldering. During this process, surface tension will act on the melted solder, displacing the end portions
30
a,
30
b.
As a result, the entire piece of the metal
30
comes under alignment relative to the locations applied with solder
35
. This process is referred to as the self-alignment. Once the alignment is made for the metal piece
30
, the solder
35
is allowed to cool as mentioned earlier.
According to the connection shown in
FIG. 9
, only one end portion
11
A is soldered. Therefore, there is no self-alignment on the end portion
11
B. Further, the connection shown in this figure also has a following problem:
Specifically, as shown in
FIG. 12
, the substrate
10
can be obtained from a single master substrate
3
, by forming a regular pattern of the substrate
10
, and then separating individual substrates
10
from this master substrate
3
. As will be easily understood, the single master substrate
3
should preferably yield as many individual substrates
10
as possible for reasons of manufacturing cost. Each substrate
10
is soldered with the metal terminal
11
before the substrate is separated from the master substrate
3
. For this reason, the substrate
10
before separation must be spaced sufficiently away from each other to allow for a projected portion of the metal terminal
11
. As a result, yield from the master substrate
3
must be sacrificed.
According to the connection shown in
FIG. 10
, the entire back surface of the metal terminal
11
′ is soldered to the substrate
10
′. Thus, the metal terminal
11
′ will self-align in the re-flow soldering. In addition, the metal terminal
11
′ does not project out of the substrate
10
′. Therefore, a single master substrate can yield an efficient number of the printed board
1
′. However, even in the arrangement shown in
FIG. 10
, there is a problem in which the metal terminal
1
′ is dislocated off the alignment as described below:
As already mentioned, in actual use of the printed boards
1
,
1
′, the metal terminals
11
,
11
′ are respectively attached with conductive elements
12
,
12
′. The attachment is achieved usually by spot welding. The spot welding is performed as follows: Referring first to
FIG. 13
, the metal terminal
11
and the conductive element
12
are contacted to each other, then pinched and pressed by a pair of positive and negative terminals
2
A,
2
B. Under this state, an electric current is passed between the pair of terminals for heating a portion of intended junction. The heating will weld the members
11
,
12
together.
Now, in the printed board
1
′ shown in
FIG. 10
, the pair of metal terminal
11
′ and the conductive element
12
′ cannot be pinched by the electric terminals
2
A,
2
B. Alternatively, therefore, the metal terminal
11
′ is overlapped to an end portion of the conductive element
12
′ as shown in
FIG. 14
, and the upper face of the end portion is pressed by the pair of electric terminals
2
A,
2
B. Under this state, an electric current is passed between the pair of terminals for welding a portion of intended junction. The problem is that part of the generated heat is conducted through the bottom face of the metal terminal
11
′ to the substrate
10
′, melting the solder between the substrate
10
′ and the metal terminal
11
′, allowing the metal terminal
11
to be dislocated off the alignment.
The present invention is made under such circumstances, and it is therefore an object of the present invention to provide accurate soldering of the metal terminal to the substrate. Another object of the present invention is to provide connection of the conductive element to the aligned metal terminal, without causing the metal terminal to be dislocated off the alignment. Still another object of the present invention is to provide an arrangement for compactly attaching a conductive element to the metal terminal.
DISCLOSURE OF THE INVENTION
According to a first aspect of the present invention, there is provided a printed board comprising an insulating substrate, and at least one metal terminal. The substrate has at least one opening penetrating the substrate. The metal terminal is fixed to the substrate so as to bridge the opening.
According to the above arrangement, a bottom face of the metal terminal, which is the surface fixed to the substrate, is exposed at the opening. Therefore, it becomes possible to advantageously perform the spot welding for connecting the metal terminal to the conductive element for electrical connection to an external circuit. Specifically, it becomes possible to pinch the metal terminal and the conductive element vertically by the pair of positive and negative spot welding terminals. Under this state, an electric current is passed between the pair of terminals to generate Joule heat for welding together the conductive element and the metal terminal.
The metal terminal may be an oblong strip, and may have a first end portion and a second end portion longitudinally away from each other. By performing the re-flow soldering for fixin
Nakamura Satoshi
Tanaka Masaharu
Merchant & Gould P.C.
Paladini Albert W.
Rohm & Co., Ltd.
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