JP2789395B2 - Wire bonding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding method for connecting a first bond point and a second bond point with a wire.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor assembly device such as an IC,
There is a wire bonding process. By this step, FIG.
As shown in (1), the pad of the pellet 1 (first bonding point)
1a and lead (second bond point) 2a of lead frame 2
Is connected to the wire 3.

Various methods have been proposed as wire bonding methods in the wire bonding step. The most general method is shown in FIG. In FIG. 3, first, as shown in FIG. 3A, a ball 3 a is formed on a wire 3 extending from a lower end of a capillary 4 by spark discharge using an electric torch 5. Thereafter, the electric torch 5 moves in the direction of the arrow. Next, as shown in (b), the capillary 4 is the first
It moves above the bonding point 1a. Subsequently, as shown in (c), the capillary 4 descends and connects the ball 3a at the tip of the wire 3 to the first bond point 1a. Thereafter, as shown in (d), the capillary 4 rises. Subsequently, as shown in (e), the capillary 4 moves above the second bond point 2a. Next, as shown in (f), the capillary 4 descends to connect the wire 3 to the second bond point 2a. Thereafter, after the capillary 4 is raised to a predetermined position, the clamper 6 is closed, and both the capillary 4 and the clamper 6 are raised, and the wire 3 is cut as shown in FIG. This allows
One wire connection is completed. Japanese Patent Application Laid-Open No. Sho 5 (1988) discloses a method related to this type of wire bonding method.
JP-A-7-87143 and JP-B-1-26531.

[0004]

In the above prior art, the distance L ₁ (see FIG. 4 ) for moving the capillary 4 from the first bond point 1a to the second bond point 2a is determined by the distance between the first bond point 1a and the second bond point. equal to the distance _{L 0} connecting the point 2a. By the way, the connection to the first bond point 1a (see FIG. 3 (c))
The ball 3a is pressed by the entire circumference of the lower end of the capillary 4. However, the connection to the second bond point 2a is made by the first bond point 1 of the capillary 4 as shown in FIG.
This is performed by the lower surface on the a side. Therefore, when equal distances L ₁ for moving the capillary 4 as in the prior art the distance L ₀ of the first bonding point 1a and the second bonding point 2a, the wire 3 is first bonded only ΔL from the second bonding point 2a Point 1
Connected to a side, poor bonding accuracy.

It is an object of the present invention to provide a wire bonding method capable of performing high-precision bonding.

[0006]

According to a first aspect of the present invention, there is provided a wire bonding method for connecting a first bond point and a second bond point with a wire.
The distance to move the capillary from the first bond point to the second bond point is determined by the radius of the outer circumference of the lower end of the capillary.
The length of the first half of the total length of the bottom hole
The wire is connected to the second bond point by moving the wire more than the distance from the bond point to the second bond point.

[0007]

The distance by which the capillary is moved from the first bond point to the second bond point is determined by the outer radius of the lower end of the capillary.
It is half the length of the bottom of the capillary plus the radius of the hole
Then , it is moved more than the distance from the first bond point to the second bond point. As a result, when the capillary moves over the second bond point, the center of the bond surface on the lower surface of the capillary on the first bond point side is located at the second bond point. For this reason, the bonding accuracy is improved.

[0008]

An embodiment of the present invention will be described below with reference to FIG. The capillary 4 is moved from the first bond point 1a to the second bond point 2a to connect the wire 3 to the second bond point 2a. In this case, the distance _{L 2} for moving the capillary 4 to the second bonding point 2a from the first bonding point 1a is longer by [Delta] L ₀ from the distance _{L 0} from the first bonding point 1a to the second bonding point 2a. Here, ΔL ₀ is set to be substantially equal to the length of the center 6 of the capillary 4 from the center 5 of the bonding surface of the capillary 4 at the time of bonding to the second bonding point 2 a, or to the length of the outer circumference of the capillary 4. 4 is a length obtained by adding the lower end hole radius dimension r to half the length obtained by subtracting the lower end hole radius dimension r. This relationship can be expressed as a number
It looks like 1. That is, the capillary 4 is moved to the first bond point 1
The distance _{L 2} is moved from a to second bonding point 2a is Canon
The lower end hole of the capillary 4 is formed at the lower end outer radius radius R of the capillary 4.
Half length ΔL ₀ = (R +
r) / 2 from the first bond point 1a to the second bond point 2a
Many move than the distance L ₀ up.

(Equation 1) ΔL ₀ = (R−r) / 2 + r = (R + r) / 2

As described above, when the capillary 4 is moved by L ₂ , the center 5 of the bonding surface of the capillary 4 coincides with the second bonding point 2a, so that the bonding accuracy is improved. Although the above embodiment has been described with reference to the case where the bonding surface of the capillary 4 is a plane, it is needless to say that the present invention can be applied to a case where the bonding surface is formed in an arc.

[0010]

According to the present invention, the distance to move the the capillary from the first bonding point to the second bonding point, the capillary
Add the radius of the bottom edge of the capillary to the radius of the bottom
The capillary is moved by a half of the obtained length more than the distance from the first bonding point to the second bonding point, so that the center of the bonding surface on the lower surface of the capillary on the first bonding point side is located at the second bonding point. The bonding accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a wire connection state to a second bond point according to an embodiment of the present invention.

FIG. 2 is a plan view of a wire-bonded sample.

FIG. 3 shows the most common wire bonding method,
(A) thru | or (g) are process drawings.

FIG. 4 is a diagram showing a conventional example in which a wire is connected to a second bond point.

[Explanation of symbols]

1a First bond point 2a Second bond point 3 Wire 4 Capillary 5 Center of bond surface of capillary 6 Center of capillary L ₀ Distance from first bond point to second bond point L ₂ Distance for moving capillary ΔL ₀ Move much The length to be made R The outer radius of the lower end of the capillary r The radius of the lower end of the capillary

Claims (1)

(57) [Claims] In a wire bonding method for connecting a first bond point and a second bond point with a wire, a distance for moving the capillary from the first bond point to the second bond point is determined by an outer radius of a lower end of the capillary. Under the capillary
A wire bonding method characterized in that the wire is connected to a second bond point by moving the wire by a length that is a half of a length including an end hole radius dimension more than a distance from a first bond point to a second bond point. .