JP3017004B2 - Wire bonding method using solder wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing various electronic parts, for example, a first bonding portion such as a semiconductor chip mounted on a lead frame or a printed board, and a lead terminal on the lead frame or a circuit on the printed board. Between the second bonding portion such as a pattern,
The present invention relates to a wire bonding method using a solder wire as the metal wire when performing wire bonding with a thin metal wire.

[0002]

2. Description of the Related Art In this type of wire bonding, a gold wire or a copper wire is generally used as a metal wire. However, the gold wire is very expensive and the cost is greatly increased. In addition, since a gold wire or a copper wire cannot be used as a temperature fuse or an overcurrent fuse because of its high melting point, a solder having a low melting point has recently been used instead of the gold wire or the copper wire. There is a need to use wires.

Meanwhile, when the metal wire used for wire bonding gold wires or copper wires, due to its high melting point, by blowing the way by heating, this
Since a relatively large lower end ball portion can be easily formed at the lower end of the metal wire at the same time as the fusing operation , the occurrence of bonding errors in bonding to the first bonding portion can be reduced.

[0004]

However, when a solder wire is used, its melting point is low. Therefore, it is extremely difficult to form a lower ball portion at the lower end of the solder wire only by melting the middle of the solder wire by heating. Difficult (this field
The reason is that the molten solder melts at the same time
In addition, it is considered that the first bonding portion is strongly oxidized by the melting, so that the bonding strength to the first bonding portion is reduced, and the wire bonding error frequently occurs.

According to the present invention, a lower end ball portion having a large diameter can be reliably formed at a lower end of a solder wire in a state where oxidation is reduced, thereby increasing the bonding strength of the solder wire to a first bonding portion. An object of the present invention is to reduce the occurrence of wire bonding errors.

[0006]

In order to achieve this technical object, the present invention relates to a method for holding a solder wire in a substantially vertical shape by a bonding tool, and moving the solder wire by a first bonding by moving the bonding tool. in parts and wire bonding method as wire bonding between the second bonding portion, said Bonde
Of the solder wires held by the bonding tool
The oxygen-free gas flow is located at the lower end projecting below the
After forming the lower end ball portion by heating and melting in a state where it is blown , the lower end ball portion is bonded to the first bonding portion by the downward movement of the bonding tool, and then the bonding tool Only after ascending, the bonding of the solder wires
Shearing the middle part between the tool and the first bonding part
Cutting by a cutting mechanism into a portion held by the bonding tool and a solder wire piece bonded to the first bonding portion, and bending the solder wire piece in the direction of the second bonding portion. Te, while bonding the tip to the second bonding portion, said
One of the solder wires held by the bonding tool
An oxygen-free gas at the lower end projecting below the
Bottom ball by heating and melting while blowing
Forming a portion . It is.

[0007]

[Operation] In this manner, held by the bonding tool
Of the solder wire below the bonding tool
With the flow of oxygen-free gas blown against the protruding lower end
After the lower end ball portion is formed by heating and melting, the lower end ball portion is bonded to the first bonding portion by the downward movement of the bonding tool,
After raising only the bonding tool, the bonding tool and the first bonder among the solder wires are moved.
And cutting the intermediate portion between the second bonding portion and the portion held by the bonding tool into a portion held by the bonding tool and a solder wire piece bonded to the first bonding portion. And bond the tip to the second bonding portion
On the other hand, the solder wire held by the bonding tool
Lower end of which projects under side than the bonding tool out of ya
Heat and melt while blowing a stream of oxygen-free gas
By forming the lower ball portion by heating, the lower ball portion with respect to the lower end of the solder wire is always heated and melted in an oxygen-free gas atmosphere at the lower end of the solder wire projecting downward from the bonding tool. The lower ball portion having a much larger diameter than in the case where the middle of the solder wire is melted by heating, in a state where oxidation on the surface of the lower ball portion is suppressed,
It can be formed reliably.

Further , the cutting of the solder wire is performed by a shearing type cutting.
By using the cutting mechanism, the
Of the solder wire held below the bonding tool
The size and shape of the lower end protruding into
Is it possible to make it more uniform than when it is cut off?
The variation in the size of the lower end ball formed at this lower end
The attachment can be reliably reduced, and the large bottom ball portion is stable.
It can be formed in different sizes .

[0009]

As described above, according to the present invention, the bonding strength and reliability of the solder wire to the first bonding portion in the work can be significantly improved, so that the occurrence of wire bonding errors in wire bonding with the solder wire can be ensured. It has the effect of being able to reduce.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 to FIG. 5 show a first embodiment.

In the first embodiment, an electrode portion C1 of a semiconductor chip C die-bonded to an upper surface of the lead frame B, and a lead terminal B1 is wire-bonded with the solder wire 11.

In this figure, reference numeral 12 denotes a vertically movable capillary tool which is one embodiment as a bonding tool.
Is disposed substantially vertically above one electrode portion C1 of the semiconductor chip C, and the solder wire 11 is inserted into the capillary tool 12 downward from above to thereby obtain the solder. The wire 11 is held substantially vertically.

Between the capillary tool 12 and the semiconductor chip C, a gas ejection tube 13 having an ejection hole 13a on the upper surface is disposed so as to move in the lateral direction. Spout hole 13 in the gas spout tube 13
a moves forward so as to be located at a position directly below the capillary tool 12, and then is added to an inert gas such as nitrogen gas or argon gas, or approximately 4 to 5
% Of an oxygen-reducing gas, such as a redox gas, which is formed by mixing about 2% of hydrogen gas, and ejecting the oxygen-free gas upward from the ejection hole 13a as indicated by an arrow D, thereby forming the solder wire. A flow of an oxygen-free gas is blown upward from below to the lower end of 11 that projects below the capillary tool 12.

A fixed scissor piece 20b and a movable scissor piece 20 are provided between the gas ejection tube 13 and the semiconductor chip C.
and a shearing-type cutting mechanism 20 composed of a.

[0016] Then, under the state wherein the lower end of the solder wire 11 and this not abut blown directly anoxic gas you ejection <br/> from ejection holes 13a in the gas injection pipe 13, the hydrogen Hydrogen torch flame 14a ejected from torch nozzle 14
Heats and melts from the side.

Then, the molten solder at the lower end of the solder wire 11 grows into a large sphere due to surface tension without being oxidized and solidifies.
As shown in FIG. 2, a lower end ball portion 11a having a large diameter can be formed at the lower end of the first member 1.

When the lower end ball portion 11a is formed at the lower end of the solder wire 11 in this manner, as shown in FIG.
The gas ejection pipe 13 is retracted from below the capillary tool 12 in a state in which the gas supply valve (not shown) to the gas ejection pipe 13 is closed to stop the ejection of the oxygen-free gas, and the hydrogen torch nozzle 14 But Capillary Tool 1
2, the movable scissor piece 20a of the cutting mechanism 20 is retracted, and then the capillary tool 12 is moved downward, whereby the solder wire 11 is moved.
The lower end ball portion 11a at the lower end of the semiconductor chip C
Is bonded to one electrode part C1.

When the bonding is completed, as shown in FIG. 4, after the capillary tool 12 moves upward, the middle of the solder wire 11 is held by the bonding tool 12 by a shearing type cutting mechanism 20. And a solder wire piece 11 'bonded to the first bonding portion.

Following this cutting, the capillary tool 12
As shown in FIG. 5, while returning to the state of FIG. 1, while repeatedly forming the lower end ball portion 11 a at the lower end of the solder wire 11 protruding from the capillary tool 12,
The solder wire piece 11 ′ cut in a state of being bonded to the electrode portion C 1 of the semiconductor chip C is bent by appropriate means in the direction of the lead terminal B 1 as the second bonding portion, and then pressed by the bonding tool 21. This is bonded to the lead terminal B1.

In particular, according to the first embodiment, the step of forming the lower end ball portion 11a on the solder wire 11 and the step of bonding the tip of the solder wire piece 11 'to the lead terminal B1 are time-dependent. By wrapping, the time required for wire bonding can be reduced.

FIG. 6 shows a second embodiment.

In the second embodiment, a cover 19 covering the entire lead frame B is attached to the block A, and a jet hole 19a is formed on the upper surface of the cover 19,
The capillary tool 1 is located above the ejection hole 19a.
2. Arrange the hydrogen torch nozzle 14 and the cutting mechanism 20,
The redox gas supplied into the cover body 18 from the ejection hole 19a is ejected as shown by an arrow E, thereby causing the lower end of the solder wire 11 inserted into the capillary tool 12 to have a redox property. The flow of gas is directly blown upward from below, and the above-described wire bonding is performed in the ejection holes 19a.

It should be noted, in the above respective embodiments, but was to use the hydrogen torch flame 14a ejected from hydrogen torch nozzle 14 as heat melting means, the present invention is, however, as shown in FIG. 7 8, the lower end of the solder wire 11 is heated and melted by moving the electric heater body 16 from the side, or as shown in FIG.
A spark torch 17 is provided upward in the gas ejection tube 13, and a spark discharge is generated between the spark torch 17 and a lower end of the solder wire 11, thereby forming the solder wire 1.
The lower end of the solder wire 11 is heated and melted, and the lower end of the solder wire 11 is heated and melted by a laser beam emitted from a laser beam transmitter 18 as shown in FIG. You can do it.

[Brief description of the drawings]

1 is a diagram of a first working state diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram of a second operation state in the first embodiment.

FIG. 3 is a diagram of a third operation state in the first embodiment.

FIG. 4 is a diagram of a fourth operation state in the first embodiment.

FIG. 5 is a diagram of a fifth operation state in the first embodiment.

FIG. 6 is a diagram showing a second embodiment of the present invention.

FIG. 7 is a view showing a modification of the heating and melting means.

FIG. 8 is a view showing another modification of the heating and melting means.

FIG. 9 is a view showing still another modification of the heating and melting means.

[Description of References] A Block body B Lead frame B1 Lead terminal C Semiconductor chip D Oxygen-free gas flow E Redox gas flow 11 Solder wire 11a Lower ball portion 11 'Solder wire piece 12 Capillary tool 13 Gas ejection pipe 13a Spout hole 14 Hydrogen torch nozzle 16 Electric heater 17 Spark torch 18 Laser beam transmitter 19 Cover body 19a Spray hole 20 Shear type cutting mechanism

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Chojiro Kuriyama 21 Saito Mizozakicho, Ukyo-ku, Kyoto

Claims (1)

(57) [Claims] 1. A wire in which a solder wire is held in a substantially vertical shape by a bonding tool, and the solder wire is wire-bonded between a first bonding portion and a second bonding portion by moving the bonding tool. In the bonding method, a solder wire held by the bonding tool is used.
No acid on the lower end protruding below the bonding tool
After forming the lower end ball portion by heating and melting in a state where the flow of the raw gas is blown , the lower end ball portion is bonded to the first bonding portion by the downward movement of the bonding tool, After lifting only the bonding tool, the solder wire
Halfway between the bonding tool and the first bonding part
And cutting the solder wire piece into a portion held by the bonding tool and a solder wire piece bonded to the first bonding portion by a shearing type cutting mechanism. And bond the tip to the second bonding portion .
On the other hand, the solder wire held by the bonding tool
Lower end protruding below the bonding tool
Heat and melt while blowing a stream of oxygen-free gas
A wire bonding method using a solder wire, characterized in that a lower end ball portion is formed by using a solder wire.