Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2001-03-07
2002-12-10
Sherry, Michael (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S1540PB, C228S103000, C228S110100, C228S180500
Reexamination Certificate
active
06492828
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to schemes for detecting bonding status of a bonding wire of a semiconductor package, particularly a package in which the resistance resulting from the adhesion layer and Cupric Oxide layer between the semiconductor unit (such as a chip or die) and its carrier is not low enough for forming a current loop.
BACKGROUND OF THE INVENTION
The electrical connection status between a bonding wire and a semiconductor unit as well as that between the bonding wire and a solder ball pad in a package shall always be checked to see if it is good after wire bonding process. As shown in
FIG. 1
, after bonding wire
35
was bonded to a bonding pad
6
(or called wire bonding pad) of a semiconductor unit
1
to make an electrical connection between the bonding wire
35
and the semiconductor unit
1
, it is bonded to bonding finger
10
, which is followed by cutting off the bonding wire
35
at a proper position (such as the location slightly left to the point
18
in the figure), so that the capillary
24
of wire bonding machine may continue bonding another bonding wire to another wire bonding pad of semiconductor unit
1
. After capillary
24
completes bonding wire bonding pad
6
by bonding wire
35
, wire bonding machine applies an electrical potential difference between bonding wire
35
and a press plate
14
, thereby a current is expected to flow through bonding wire
35
(the part between capillary
24
and bonding pad
6
), bonding pad
6
, semiconductor unit
1
, conductive adhesion layer
2
, heat dissipater
3
, and hot plate
14
back to the wire bonding machine to form a loop current (the direction shown by arrows
45
,
46
, and
47
is a possible current flowing direction). In case the bonding status between bonding wire
35
and bonding pad
6
is not good, the loop current will be very small or negligible as a result of bad electrical connection between bonding wire
35
and wire bonding pad
6
. A normal loop current resulting from normal bonding status will thus be indicative of the good bonding status (good electrical connection) between bonding wire
35
and semiconductor unit
1
.
Shown in
FIG. 2
is a conventional art in which a layer
4
of Cupric Oxide is coated on a surface of heat dissipater
3
in order to enhance the adhesive force between heat dissipater
3
and semiconductor unit
1
, encapsulant body, as well as substrate
7
, resulting in the infeasibility of forming the loop current because the layer
4
of cupric oxide is nonconductive. This is why the current direction represented by arrow
47
of
FIG. 1
does not exist in
FIG. 2
, leading to the extreme difficulty of detecting the bonding status (or called electrical connection status) between bonding wire and semiconductor unit in a package, particularly during wire bonding process.
Although the arts disclosed by U.S. Pat. Nos. 5,712,570 and 5,893,508 are also used for detecting the bonding status of bonding wire in a semiconductor package, they are subject to a condition: chip and its carrier or some devices on its carrier form a conductive path for a current loop, therefore these arts cannot be applicable to the case illustrated in
FIG. 2
where the layer
4
of Cupric Oxide or the adhesion layer
2
is not electrically conductive. The present invention is thus developed to resolve the problem resulting from either the nonconductive layer of Cupric Oxide or the nonconductive adhesion layer, and thereby to provide convenience for related industries to take advantage of the benefit of the layer of Cupric Oxide, while still be able to detect the bonding status of a bonding wire when packaging a Ball Grid Array package or similar types of packages, leading to more convenient, more systematic, and more flexible operation for detecting the bonding status of bonding wires in a semiconductor package, particularly during wire bonding process.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method associated with a wire bonding machine or a wire bonding process, for detecting bonding status of a bonding wire of a Ball Grid Array package or similar types of packages (such as those with solder ball pads thereof located on the same surface of a substrate as are semiconductor units thereof), the method achieving more convenient, more systematic, more flexible or less confined (allows the existence of insulation between semiconductor unit and its carrier, for example) schemes for detecting bonding status of a bonding wire, particularly for detecting abnormal bonding status during wire bonding process in order to make up it early enough.
Another object of the present invention is to provide a system associated with a wire bonding machine or a wire bonding process, for detecting bonding status of a bonding wire of a Ball Grid Array package or similar types of packages (such as those with solder ball pads thereof located on the same surface of a substrate as are semiconductor units thereof), the system achieving more convenient, more systematic, more flexible or less confined (allows the existence of insulation between semiconductor unit and its carrier, for example) schemes for detecting bonding status of a bonding wire, particularly for detecting abnormal bonding status during wire bonding process in order to make up it early enough.
A further object of the present invention is to provide the industries related to Ball Grid Array package or similar types of packages, with the convenience or flexibility of selecting, according to individual requirements or conditions, proper schemes for detecting the bonding status of bonding wires of a package. For example, it provides convenience or flexibility of selecting from among the three schemes: only detecting the bonding status between bonding wire and semiconductor unit, only detecting the electrical connection status between bonding wire and solder ball pad, and detecting both the above.
The present invention may be represented by a system associated with a wire bonding process, for detecting bonding status of at least a bonding wire of a package including at least a semiconductor unit and at least a package-connection-means such as solder ball pad. The system primarily comprises: at least a carrier such as a substrate, a heat dissipater, or a piece of tape, or any object capable of supporting the semiconductor unit and/or package-connection-means; at least an electrical conduction means such as an object made of electrically conductive metal, or electrically conductive rubber, or anisotropically conductive film, or the combination of these material, the electrical conduction means contacting at least a selected one of the package-connection-means; at least a preset connection means such as an electrical connection system (an electric wire or a system composed of a trace, a bonding finger, and a bonding wire, for example) established in the beginning of the wire bonding process, for electrically connecting the selected one of the package-connection-means and the semiconductor unit; a voltage source which may be a direct or alternate source or a capacitor, for providing an electrical potential difference between the electrical conduction means and the bonding wire; and a detector such as a current meter, for measuring, when the bonding wire is so bonded (by the wire bonding process, for example) as to electrically connect at least one of the semiconductor unit and the package-connection-means, a current passing the voltage source, and for providing, according to the measured current, at least a status indicating signal reflecting the bonding status (or electrical connection status) between the bonding wire and the semiconductor unit, and/or the bonding status (or electrical connection status) between the bonding wire and a component which may be a bonding finger on the carrier supporting the package-connection-means, and which electrically connects the package-connection-means via the carrier (a trace on the carrier, for example) supporting the package-connection-means.
The prese
Chin-Te Chen
Ming-Hsun Lee
Klarquist & Sparkman, LLP
Nguyen Tung X.
Sherry Michael
Siliconware Precision Industries
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