JPS6333295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire bonding method and apparatus.

When assembling semiconductor devices, semiconductor integrated circuit devices, etc., when connecting pellets (circuit elements) and leads with extremely thin wires (gold wire, etc.), if the bonding is not done with wires of the appropriate length, the first bonding point and the first bonding point If the wire loop connecting the two bonding points is too long or too short, the wire may come into contact with an undesired part (device or external lead, etc.), causing shoot failure.

For this reason, wire bonding is performed with a constant tension always applied to the wire being held, so that the wire can smoothly protrude or return within the capillary that holds the wire, and achieve the desired result. Care is taken to form a wire loop.

However, the distance between bondings varies even in the assembly of a single semiconductor device, and it is difficult for all the wire loops to have a desired shape with the above-described tensioning method. That is, for example, if the distance between bondings is long, it is necessary to draw more into the capillary, which is a bonding tool, and if the distance between bondings is short, the amount of drawing into the capillary needs to be smaller.

On the other hand, a clamper that grips and breaks the wire operates as shown in FIG. That is, the clamper clamps the wire when the first bonding (B _P ) and the second bonding (B _L ) are completed, grasps the wire, and pulls it, and the first bonding can be performed from the time when the wire breaks. The wire is clamped until such a state is reached (for example, the tip of the Au wire is made into a ball shape so that the wire does not come out of the capillary). In addition,
The solid line indicates the vertical movement of the capillary, and the chain line indicates the opening/closing operation of the clamper.

Therefore, by clamping the wire with this clamper before the second bonding, the wire that has come out of the capillary more than necessary is pulled back into the capillary, thereby creating a proper wire loop. I thought about shaping it.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a wire bonding method and apparatus that can form a proper wire loop.

The gist of the present invention to achieve such an object is to crimp and fix the tip of the wire to the first bonding point while holding the wire with a bonding tool, and then crimping and fixing the tip of the wire at the first bonding point while untying the wire from the bonding tool. In the wire bonding method, the wire is crimped and fixed at two bonding points, and then the wire is grabbed with a clamp and pulled to break near the second bonding part, wherein the bonding tool reaches the second bonding point from the first bonding point. The wire is gripped by a clamper used to break the wire in between, and the time point at which the wire is clamped is varied depending on the distance between the bonding points from the first bonding point to the second bonding point. A wire bonding method characterized by controlling a wire loop between a bonding point and a second bonding point.

The present invention will be explained below with reference to Examples.

2a and 2b show an embodiment of the wire bonding method of the present invention. In both cases, the capillary 1 holds (clamps) the wire 2, and after fixing the tip of the wire 2 to the electrode (first bonding point) of the pellet 4 fixed on the tab 3, the capillary 1 is raised as shown by the arrow. , horizontally move and lower the wire 2 to press and fix the middle of the wire 2 to the lead (second bonding point) 5. Then, the clamper 6 grabs the wire 2 and as the capillary 1 rises, the wire 2 is moved to the second bonding point.
A stretch of wire bonding is completed by breaking near the bonding point. by the way,
Figure a shows capillary 1 during the second bonding work.
shows the state in which the clamper 6 closes and clamps the wire 2 at a high position;
This shows a state in which the clamper 6 closes and clamps the wire 2 at a low height position. In the former case, where the capillary 1 is at a high position, the clamper 6 closes earlier, so that the wire 2 is pulled back into the capillary 1 more than in the latter case. In this way, if the closing operation (clamping) of the clamper is performed in accordance with the distance between bondings, the desired wire loop can be obtained, and shot defects caused by wire collapse due to the wire loop being too large can be avoided. Shooting defects due to insufficient wires do not occur because hill-shaped wire loops are not formed. Note that FIG. 4 shows an example of the clamper 6, which is fixed to a clamp arm (not shown) and located above the capillary.
The wire 2 is held by a pair of claws 8 that are mutually opened and closed by an electromagnet 7. In the figure, 9 is a spring that closes the pair of claws 8, and 10 is a ring-shaped wire guide fixed to one of the claws.

The opening/closing operation of the clamper 6 is as shown in Fig. 3.
Controlled by the clamper opening/closing circuit. A pulse signal is sent from the encoder to the clamper opening/closing circuit, and bonding data is sent from the memory to the comparator. A comparator compares the bonding distance (L) with a plurality of preset reference distances. And L
When is l ₁ (or less than l ₁ ), the clamper closes and holds the wire at the N _1st pulse number after T ₁ hour. Also, when L is l ₂ (or more than l ₂ )
T ₂ hours later N The clamper closes at _{the second} pulse. In actual wire bonding, a reference distance of 2 to 3 is sufficient. Further, the number of pulses during one-tension wire bonding is always constant.

According to such an embodiment, since the point at which clamping of the wire starts can be freely controlled, the length of the wire forming the wire loop can be controlled in accordance with the bonding distance, and a desired wire loop can be formed. In addition, in this embodiment, the second
Before bonding, the wire is clamped and the capillary is lowered in this state, so the wire is squeezed and crushed (crimped). As a result, the rising angle of the crimped part of the wire increases, and when the wire breaks, the wire breaks near the crushing of the second bonding point, and the broken part of the wire extends long from the crimped part (tail). ) so it doesn't remain. Therefore, contact with other wires etc. does not occur.

Note that the present invention is not limited to the above embodiments.

As described above, according to the present invention, the wire length can be freely adjusted during wire bonding, so that an appropriate wire loop that does not cause shoot defects can be formed. Further, since no tail is left behind, shot defects can be prevented and yields can be improved.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the movement of the capillary and clamper, Fig. 2 a and b are explanatory diagrams showing the wire bonding state according to an embodiment of the present invention, Fig. 3 is a block diagram, and Fig. 4 is a graph showing the movement of the clamper. The perspective view, FIG. 5, is also a graph showing the movement of the clamper. 1... Capillary, 2... Wire, 3... Tab, 4... Pellet, 5... Lead, 6... Clamper, 7... Electromagnet, 8... Claw, 9... Spring, 10... Wire guide .

Claims (1)

[Claims] 1 After crimping and fixing the tip of the wire to the first bonding point while holding the wire with a bonding tool, crimping and fixing the middle of the wire to the second bonding point while untying the wire from the bonding tool, and then grasping the wire with a clamper. In the wire bonding method in which the wire is pulled and broken near the second bonding part, the bonding tool is a clamper used to break the wire while the wire is being pulled from the first bonding point to the second bonding point. controlling the wire loop between the first bonding point and the second bonding point by gripping the wire and changing the point at which the wire is clamped according to the distance between the bonding points from the first bonding point to the second bonding point; A wire bonding method characterized by: