JPH07106374A - Bonding tool - Google Patents

Abstract

PURPOSE:To make possible the stable use of a bonding tool usable over a long period of time by a method wherein the junction interfaces of a tool point part and a tool shank part are joined together, heat from the side of the shank part is made easy to transfer to the point part, the distribution of the tempera ture of the tool and the temperature response characteristic of the tool are improved and crack and breakage in the point part consisting of a hard sub stance is prevented from being generated. CONSTITUTION:A semiconductor packaging bonding tool, which consists of a tool point part 1 and a tool shank part 2, has an intermediate layer 3 consisting of one layer of the soft metal layer or two or more layers of the soft metal layers, which is/are selected from among soft metal layers, such a gold, silver, copper, platium, tantalum, nickel and aluminum layers, between the point part 1 and the shank part 2 and the point part 1 is mechanically fixed to the shank part 2 by pressing the point part 1 to the side of the tool shank part 2 by a plane, which is provided on a locking means 4 and has an area of 10mm<2> or wider.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a bonding tool used when mounting semiconductor elements such as ICs and LSIs.

[0002]

2. Description of the Related Art In order to bring out the electrical characteristics of a semiconductor element, it is necessary to electrically connect an electrode formed on the semiconductor element to a lead of a package and the lead and an external terminal such as a wiring board. is there. Conventionally, the electrode on the semiconductor element side and the lead wire are joined together by using a metal thin wire made of gold or copper as a conducting wire and using a tool called a capillary.
A method called wire bonding in which each piece is joined, and a lead wire called a film carrier tape formed by plating tin on a patterned copper foil is heated to a predetermined temperature using a bonding tool to form all electrodes on a semiconductor element. TAB method (Tape A
It is carried out by a method called utomated Bonding).

On the other hand, a lead wire is connected to an external terminal such as a wiring board or a lead frame by using a tin-plated lead wire or a lead wire which is not plated and a solder electrode formed on the wiring board by screen printing or the like. Or a gold-plated lead wire is bonded to a gold-plated or silver-plated lead frame using a bonding tool heated to a predetermined temperature.

The bonding tools used here are conventionally Mo, Fe--Ni alloys, Ni alloys, Ti and Ti.
Alloys, W and W alloys, Fe-Ni-Co alloys, and other metal tool shanks are used to improve the flatness of the tool surface, wear resistance, and temperature distribution. Crystal, diamond sintered body, cBN
A tool tip made of a hard material such as a sintered body or silicon nitride is attached, and it is used by heating it to a predetermined temperature by inserting a heater into the tool shank of the bonding tool. .

[0005]

In recent years, semiconductor elements have tended to become larger and longer due to their multi-functionality and higher integration.
Furthermore, in order to improve the mounting efficiency, a method of mounting a plurality of semiconductor elements at a time has begun to be adopted, and in response to this, the bonding tool is also required to be large and long. Especially when joining the lead wire of the film carrier tape to the wiring board or lead frame, the pressing load of the bonding tool tends to increase in order to obtain a reliable joining strength as well as the size of the tool tip. It is in.

However, as the bonding surface becomes larger or longer, the tip portion of the tool also becomes larger, which tends to increase the joint area with the tool shank portion. Generally, the hard material used for the tip portion of the tool has a lower coefficient of thermal expansion than the tool shank portion. Therefore these two
When the two parts are joined by brazing, the thermal stress generated at the joint interface becomes even greater, which causes the problem that the tip of the tool separates from the tool shank during use. Even if peeling did not occur, the tool pressing surface was warped due to the effect of internal thermal stress, and the tip of the tool was cracked due to repeated mounting loads.

In order to solve this problem, a method of fixing the joining of the tool shank portion and the tip portion of the tool with a screw or a clamp pin has been proposed by the applicant (Japanese Patent Laid-Open No. 3-191538). However, in this case, even a joint surface that has been carefully processed has a warp of several μm to 10 μm, and due to the influence of surface roughness, the entire joint surface of the tool tip and tool shank part Do not contact each other uniformly, the heat applied from the heater to the tool shank side is not sufficiently transmitted to the tool tip, and the temperature distribution of the tip pressing surface and the followability of temperature rise / fall, that is, the temperature responsiveness It was inferior to the accessories.

Furthermore, since the tool tip portion, which is mainly made of brittle material, is fixed to the tool shank portion directly by screwing, clamping pin fastening, etc., a tightening force is applied to a narrow range of the tool tip portion, so that it is in use. There was also a problem that the tip of the tool was chipped, cracked or loosened.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and provides a semiconductor mounting bonding tool comprising a tool tip and a tool shank. Gold between the tool shanks,
It has one or more intermediate layers selected from soft metals such as silver, copper, platinum, tantalum, nickel, and aluminum, and the tool tip has an area of 10 mm ² or more provided on a metal stopper. A flat surface having a contact point with the tool tip portion, and the stopper is pressed against the tool shank portion side to thereby mechanically fix it, and the soft metal of the intermediate layer has a thickness of 1 layer. The width is 0.005 mm or more and 10 mm or less.

In the bonding tool of the present invention, by inserting a soft metal into the bonding interface between the tool tip and the tool shank portion, the deformation of the metal is used to bring the bonding interfaces into close contact with each other, so that the shank side The heat can be easily transferred to the tip of the tool, and the temperature distribution and temperature response of the tip can be improved. The soft metal layer preferably has a thickness of 0.005 mm or more and 10 mm or less per layer.

Further, since the tool tip portion is applied with a tightening force on the tool shank portion side in a plane of 10 mm ² or more provided on the stopper, the tool tip portion does not come into direct contact with the screw, so that it is made of a hard substance. The tip of the tool will not be cracked or chipped, and stable use will be possible for a long time. In addition, gold is also used at the contact interface between the stopper and the tip of the tool,
By inserting one or more metals selected from soft metals such as silver, copper, platinum, tantalum, nickel and aluminum, the attachment force applied to the tool tip becomes more uniform.

[0012]

The bonding tool of the present invention will be described in detail below with reference to FIGS.

The bonding tool of the present invention has a structure as shown in the exploded perspective view of FIG.
Is a tool shank, 3 is gold, silver, copper, platinum, tantalum,
An intermediate layer made of a soft metal such as nickel or aluminum,
Reference numeral 4 denotes a metal stopper, and 5 denotes a fixing screw.

To join the tool tip portion 1, the intermediate layer 3 and the tool shank portion 2, without using brazing, the stopper 4 on the tool tip portion 1 is screwed to the tool shank portion 2 with a screw 5. Mechanical joining is performed by tightening with. The tool tip portion 1 is pressed downward from above by the stopper 4 so that it is fixed to the tool shank portion 2 via the intermediate layer 3. In this case, the screw 5 is the tool tip 1
Since it passes through the convex portions on both ends of the stopper 4 which coincide with the cutout portion of the intermediate layer 3, the screw 5 and the tool tip 1 and the intermediate layer 3 do not come into direct contact with each other.

FIG. 2 and FIG. 3 show a bonding tool which is integrated by this screwing. This bonding tool is attached to a bonding device (not shown) at the device mounting portion 8 of the tool shank 2. In use, a cartridge heater is attached to the heater hole 6 of the bonding tool, and a thermocouple is attached to the thermocouple hole 7, and then the bonding tool is heated to a predetermined temperature so that the semiconductor lead wire and the lead frame are heated. , The wiring board or the like is crimped and joined by using the tip pressing surface 9.

FIG. 4 is a plan view of the bonding tool of the present invention seen from above, and the contact surface 10 between the stopper 4 and the tool tip 1 is a flat surface of 10 mm ² or more. 5 is a partially cutaway sectional view taken along the line AA of FIG.
As shown in (3), the joining portion between the tool tip portion 1 and the tool shank portion 2 has the intermediate layer 3 in between and is not in direct contact. Also, the screw 5 and the tool tip 1 are not in direct contact,
The tool tip portion 1 is pressed against the stopper 4 in a surface contact state with the contact surface 10, and is clamped and fixed to the tool shank portion 2 together with the intermediate layer 3.

In the present invention, since the tool tip portion 1 is attached to the tool shank portion 2 by mechanical joining through the soft metal intermediate layer 3, the intermediate layer 3 is deformed, and the tool tip portion 1 and the tool are Uniform contact is made over the entire joint surface of the shank portion 2. For this reason, compared to the conventional mechanical joining in which there is no soft intermediate layer and there is a gap in the joint due to the warped surface roughness of the joint surface, when the tool shank is heated, it is even The heat is transmitted. As a result, a uniform temperature distribution is obtained during heating, and the temperature rises,
It is possible to obtain a bonding tool having excellent descent response.

Further, the tool tip 1 is used as a mechanical joining means.
Since there is no threaded hole in the tool shank, and the tool shank part 2 is tightened with a stopper 4 having an area of 10 mm ² or more provided in this stopper 4, tightening in a narrow range of the tool tip. No stress is applied, and the tip of the tool is less likely to be cracked or chipped during use as in the case of mechanical joining using a conventional screw or the like directly on the tip of the tool.

[0019]

EXAMPLE A tool tip portion made of silicon carbide having two tip pressing surfaces each having a length of 30 mm and a width of 1 mm and a tool shank made of a tungsten alloy as an intermediate layer have a thickness of 0.1 mm and a purity of 99.9% gold. It was screwed with a stopper via. From the viewpoint of preventing loosening during use, the screw is heated to 550 ° C., which is the operating temperature, and tightened at that temperature. Then, as shown in FIG.
The tip of the screw 11 was processed to have the same curvature as the inner diameter of the heater hole 6 and the heater was inserted to prepare the bonding tool of the present invention having a structure in which the screw is not loosened during use.

On the other hand, for comparison, a bonding tool similar to the above was prepared without an intermediate layer of gold, and a tool shank portion and a tool tip portion were joined by silver brazing to prepare 550 ° C.
Temperature distribution, flatness, from room temperature to 55
A comparison was made regarding the durability of the joint when heating and cooling were repeated at 0 ° C. The results are shown in Table 1.

[0021]

[Table 1]

[0022]

As described above, according to the bonding tool of the present invention, the soft metal inserted into the joining interface between the tool tip and the tool shank allows the joining interfaces to be sufficiently formed by utilizing the deformation of the metal. The heat from the shank side can be easily adhered to the tool tip to facilitate transfer to the tool tip, and the temperature distribution and temperature responsiveness of the tip can be improved. Further, since the tip of the tool is joined to the tool shank with a flat surface of 10 mm ² or more provided on the stopper, it does not come into direct contact with a joining member such as a screw and is made of a hard substance. The tip of the tool will not crack or chip,
It enables stable use over a long period of time.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a structure of a bonding tool of the present invention.

FIG. 2 is a perspective view of the bonding tool of the present invention.

FIG. 3 is a front view of the bonding tool of the present invention.

FIG. 4 is a plan view of the bonding tool of the present invention.

5 is a partially cutaway sectional view taken along the line AA shown in FIG.

[Explanation of symbols]

 1 Tool Tip 2 Tool Shank 3 Intermediate Layer 4 Stopper 10 Contact Surface between Stopper and Tool Tip

Claims (2)

[Claims] 1. A bonding tool for mounting a semiconductor, comprising a tool tip and a tool shank, wherein gold, silver, copper, platinum, tantalum, nickel, aluminum or the like is provided between the tool tip and the tool shank. It has one or two or more intermediate layers selected from soft metals, and the tool tip is pressed against the tool shank side with a plane having an area of 10 mm ² or more provided on a metal stopper. Bonding tool characterized by being mechanically fixed by. 2. The bonding tool according to claim 1, wherein the soft metal of the intermediate layer has a thickness of 0.005 mm or more and 10 mm or less per layer.