Structure for inspecting electrical component alignment

Details Structure for inspecting electrical component alignment Structure for inspecting electrical component alignment

2001-12-14

2003-02-11

Paladini, Albert W. (Department: 2827)

Electricity: conductors and insulators

Conduits, cables or conductors

Preformed panel circuit arrangement

C029S832000, C257S786000, C356S401000, C348S087000, C361S777000, C382S151000

Reexamination Certificate

active

06518512

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure for inspecting the alignment of a mounted electrical component (hereinafter, referred to as a structure for inspecting the electrical component alignment), which is suitable for use in printed circuit boards used in various electronic devices.
2. Description of the Related Art
Referring to
FIGS. 5 and 6
, a known structure for inspecting the electrical component alignment will now be described. A planar insulated substrate
31
constituting a printed circuit board has a wiring pattern
34
having a first wiring pattern
32
and a second wiring pattern
33
both formed thereon, and an insulating resist layer
35
formed thereon so as to cover the wiring pattern
34
.
The first wiring pattern
32
has a plurality of connections
32
a
formed by partially removing the resist layer
35
.
An electrical component
36
has a rectangular outer casing
36
a
and a plurality of electrodes (not shown) mounted on the bottom surface of the outer casing
36
a.
Mounting of the electrical component
36
on the printed circuit board is performed by applying solder cream (not shown) on the connections
32
a
of the first wiring pattern
32
, placing the electrodes on the solder cream, and heating the printing circuit board in a furnace so as to solder the electrodes to the connections
32
a
in that order.
Surface mounting of the electrical component
36
is achieved by performing reflow soldering as described above. Alternatively, the electrodes can be soldered to the connections
32
a
in a state such that a ball grid array having metal balls adheres to the electrodes in this soldering process.
The first wiring pattern
32
is formed for mounting and wiring the electrical component
36
. The second wiring pattern
33
is additionally formed for a desired electrical circuit.
Fiducial marks
37
are formed on the resist layer
35
by silk-screen printing. More particularly, the fiducial marks
37
are formed as an L-shape at a pair of orthogonally opposing corners of the outer casing
36
a
of the electrical component
36
along the edges of the rectangular outer casing
36
a.
The fiducial marks
37
are formed on the resist layer
35
before mounting the electrical component
36
. After the electrical component
36
is mounted, visual inspection of the fiducial marks
37
is performed to determine whether or not the electrical component
36
is aligned properly relative to the fiducial marks
37
.
Since the fiducial marks
37
are formed on the resist layer
35
by silk-screen printing, the known structure for inspecting the electrical component alignment requires an additional step of silk-screen printing, thereby resulting in lower productivity and higher production cost.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a more productive and less expensive structure for inspecting the electrical component alignment.
To this end, a structure for inspecting the alignment of a mounted electrical component is provided. The structure comprises a printed circuit board having a wiring pattern and a rectangular electrical component mounted on the printed circuit board. The wiring pattern has fiducial portions extending closely along at least two mutually orthogonal outer edges of the rectangular electrical component.
The electrical component is preferably formed as a chip type comprising a rectangular outer casing and a plurality of electrodes mounted on the bottom surface of the outer casing.
The wiring pattern may further have a first wiring pattern which forms the fiducial portions extending along at least two mutually orthogonal outer edges of the electrical component.
The fiducial portions may further extend along the three or four outer edges of the electrical component.
The wiring pattern may further have a first wiring pattern for mounting the electrical component and a second wiring pattern which forms the fiducial portions extending along at least two mutually orthogonal outer edges of the electrical component.
The fiducial portions may further extend along the three or four outer edges of the electrical component.
The wiring pattern may further have a first wiring pattern for mounting the electrical component and a second wiring pattern so that the first wiring pattern and the second wiring pattern form the fiducial portions extending along at least two mutually orthogonal outer edges of the electrical component.
The structure for inspecting the alignment of a mounted electrical component may further comprise an insulating resist layer, which covers the fiducial portions, on the printed circuit board, wherein the fiducial portions are visible through the resist layer.


REFERENCES:
patent: 4776088 (1988-10-01), Biggs et al.
patent: 5627913 (1997-05-01), Spigarelli et al.
patent: 5643835 (1997-07-01), Chia et al.
patent: 5701234 (1997-12-01), Wong
patent: 4737845 (1998-04-01), Susuki et al.
patent: 5953447 (1999-09-01), Jin
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patent: 06302925 (1988-02-01), None
patent: 05-037197 (1993-02-01), None
patent: 07-240431 (1995-09-01), None
patent: 11135898 (1999-05-01), None
patent: 2000031611 (2000-01-01), None
patent: WO 9957954 (1999-11-01), None
European Search Report, issued Apr. 4, 2002, corresponding to EPA No. 01310240.5.

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