Wire structure of substrate for layout detection

Details Wire structure of substrate for layout detection Wire structure of substrate for layout detection

1999-10-08

2001-11-06

Gaffin, Jeffrey (Department: 2841)

Electricity: conductors and insulators

Conduits, cables or conductors

Preformed panel circuit arrangement

C174S261000, C361S768000, C361S777000

Reexamination Certificate

active

06313413

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a wire structure of Chip on Substrate (COS) for layout detection and more particularly to traces of a ball-side surface connecting ball pads and bonding pads through holes to the wire of a die-side surface.
2. Description of the Related Art
BGA (Ball Grid Array) packages of the electronic and computer industries have been required to support higher lead counts within the same package footprint area. BGA packaging mainly includes a substrate which provides bonding pads for wire bonding and ball pads for ball soldering. The bonding pads and ball pads of the substrate are electroplated on its surface to prevent oxidization so as to increase the bondability and solderability so that a wire electrically connects all of the traces which connect to all of bonding pads and ball pads. In order to electroplate a metal layer on the surface of all of bonding pads and ball pads, all of bonding pads and ball pads are cathodes during the electroplating process. When traces of the substrate need to be checked to determine whether bonding pads connects to ball pads, we cannot use the socket of the test machine to detect the quality of an individual trace because all traces of bonding pads and ball pads are connected to one another by a wire resulting in a closed loop of all traces. Therefore, we must use an Automatic Optical Inspection device to detect quality of the traces of the substrate. This takes a long time to complete, thus substrate detection has the drawback of low efficiency. As shown in
FIG. 1
, a substrate
100
has a plurality of bonding pads
101
and a plurality of ball pads
102
. The bonding pads
101
are located at the edge of a slot
110
of the substrate
100
for wire bonding, and the ball pads
102
are located at the periphery of the substrate
100
for ball soldering. Bonding pads
101
are connected to ball pads
102
to form a closed loop through traces
103
and holes
104
. A wire
111
is electrically connected to the extensions of all traces
103
at the edge of the substrate
100
. We must use an Automatic Optical Inspection device to detect traces of the substrate
100
, because all bonding pads
101
are connected to the corresponding ball pads
102
by the corresponding wires
111
forming a closed loop. This takes a long time to complete so that substrate detection has the drawback of low efficiency.
As shown in
FIG. 2
, a substrate
200
has a plurality of bonding pads
201
and a plurality of ball pads
202
. The bonding pads
201
are located at the edge of a slot area
210
of the substrate
200
for wire bonding, and the ball pads
202
are located at the periphery of the substrate
200
for ball soldering. Bonding pads
201
are connected to ball pads
202
to form closed loops through traces
203
and holes
204
. A first wire
211
is provided at the edge of the substrate
200
; a second sire
212
is provided in the slot area
210
and is electrically connected to the first wire
211
at the two ends of the slot area
210
. The extensions of the traces
203
in the slot area
210
are electrically connected to the second wire
212
such that the traces
203
, the first wire
211
and the second wire
212
form a closed loop. All bonding pads
201
are connected to all ball pads
202
through the first wire
211
and the second wire
212
because the traces
203
are extended to the slot area
210
for connection to the second wire
212
. Therefore, slot sawing is performed at the slot area
210
to form an opened loop between the traces
203
and the second wire
212
such that the bonding pads
201
are connected to the corresponding ball pads
202
by the traces
203
. The tensions of the traces
203
from the bonding pads
201
in the slot area
210
are too close one another and are not covered by solder mask such that the extensions are exposed on the substrate
200
. Then when slot sawing is performed at the slot area
210
, the ends of the extensions at the edge of the slot area
210
have lateral malleability and the substrate
200
is thereby broken down so that the adjacent ends are connected one another.
The present invention intends to provide a wire structure of substrate for layout detection in which traces of the ball-side surface of the substrate connect to ball pads and a wire of the chip-side surface of the substrate through holes. The wire is located at a slot area which is covered by solder mask to mount the ends of the traces to prevent a short of the traces after slot sawing. The present invention provides a wire connection to traces covered with solder mask in such a way as to mitigate and overcome the above problem.
SUMMARY OF THE INVENTION
The primary objective of this invention is to provide a wire structure of substrate for layout detection in which traces of the ball-side surface of the substrate connect to ball pads and a wire of the chip-side surface of the substrate through holes. The wire is located at a slot area on which the covering solder mask is used to mount the ends of the traces. The present invention thereby increases adhesion of the traces to the substrate to prevent the traces peeling off the substrate and being too close to the other traces after slot sawing such that the substrate of the present invention can use the socket of the test machine to increase efficiency.
The present invention is a substrate in accordance with an embodiment; the substrate mainly includes a plurality of bonding pads, a plurality of ball pads, a plurality of traces, a plurality of holes, a first wire and a second wire. The bonding pads and ball pads are located on a first surface of the surface and are connected to one another by the traces. The first wire is arranged at the edge of the first surface of the substrate; the second wire is arranged at a slot area of a second surface of the substrate which is adhesively covered by a solder mask and further has two ends connecting to the first wire. The holes connect the first surface to the second surface. The traces connect the bonding pads and ball pads of the first surface by passing through the corresponding holes and a slot area to the second wire of the second surface to form closed loops. In the slot area, the solder mask adhesively covers the traces. During the slot sawing process on the slot area, some parts of the traces of the slot area and the second wire are cut to form opened loop. Then the ends of the traces at the edge of the slot area have little lateral malleability the adjacent ends of traces cannot be connected to one another such that the substrate of the present invention can use the socket of the test machine to increase efficiency.
Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description and the accompanying drawings.


REFERENCES:
patent: 4195195 (1980-03-01), de Miranda et al.
patent: 4758459 (1988-07-01), Mehta
patent: 5572346 (1996-11-01), Sakamoto et al.
patent: 5949657 (1999-09-01), Karabatsos
patent: 6157541 (2000-12-01), Hacke

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