JP4101695B2 - Tool for thermocompression bonding and manufacturing method thereof - Google Patents

Description

[0001]
[Industrial application fields]
TECHNICAL FIELD The present invention relates to a thermocompression bonding tool used when performing thermocompression bonding such as crimping of a flip chip and a mounting base, and crimping of a liquid crystal driver and a liquid crystal glass plate, and a manufacturing method thereof. is there.
[0002]
[Prior art]
Some thermocompression bonding tools are coated with a diamond film on the crimping surface. However, conventional thermocompression bonding tools are used with the heat resistant resin film still formed, so that the flatness is sufficient. In addition, although the wear resistance when removing the adhered molten alloy can be improved, the adhesion of the molten alloy, which is the root cause, cannot be prevented, and the maintenance cost of the thermocompression bonding tool increases, which is uneconomical. There was a drawback that would be
Moreover, as shown in Patent Document 1, a technique for preventing adhesion of molten metal such as solder by applying a fluororesin coating on the surface of a crimping tool is disclosed. However, the coated crimping surface does not have a sufficiently high flatness, and is insufficient for the highly accurate crimping required in recent years. Also, since the surface of the fluororesin film after coating with fluororesin has chemically unstable reactive groups, it is not sufficient to prevent adhesion of molten metal such as solder without taking measures against metal welding. The welding becomes noticeable immediately after use.
[Patent Document 1]
Japanese Patent Laid-Open No. 07-302818
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and provides a tool for thermocompression bonding that increases the flatness of the crimping surface and prevents welding with solder, resin, etc. during heating, and a method for manufacturing the same, and heat-melt bonding The purpose is to stabilize and improve economic efficiency.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the thermocompression bonding tool according to the present invention is composed of a thermocompression bonding tool for bonding a connection terminal and a substrate disposed on a flip chip, and a bonding between a liquid crystal driver and a liquid crystal glass plate. In the thermocompression bonding tool used in the above, a heat-resistant and adhesion-resistant resin film is formed on the crimping surface of the crimping tool. The thermocompression bonding tool according to the present invention is a thermocompression bonding tool for forming a heat-resistant and adhesion-resistant resin film on the pressure-bonding surface of a crimping tool using a silk printing technique or the like, and solidifies the coated fluororesin or silicon resin. However, the surface is processed.
As the heat-resistant and adhesion-resistant coating, either a fluororesin or a silicon resin shown in the present invention, which is extremely low in reactivity with molten metal and resin and does not wet, is most suitable.
Further, the present invention is characterized in that the surface of the formed resin is removed. By removing, the reactive reactive group on the chemically unstable film surface at the time of film formation is removed, making it difficult to adhere to other materials, making the surface state of the film uniform and improving its flatness be able to. The flatness of the tool has a higher effect because it directly affects the accuracy and speed of the joining process. In addition, as a method for removing the coating surface, it is preferable to perform surface grinding or surface polishing while spraying a cooling medium such as water on the coating, since an adhesive reactive group is not formed on the coating surface.
[0005]
Further, the surface roughness of the film must have an arithmetic average roughness Ra of 10 μm or less (JIS standard 1994 version). If the surface roughness is rougher than this, the contact area between the coating and the molten metal or resin becomes large, and the molten metal or resin melts and deforms in accordance with the unevenness of the surface during cooling, and cooling unevenness is likely to occur. .
[0006]
In the tool for thermocompression bonding, a heat-resistant resin film is formed on the crimping surface, and a property that does not get wet with the molten metal or resin occurs on the crimping work surface. It will not adhere to the surface. In the method for manufacturing a thermocompression bonding tool, a heat-resistant resin film is formed in a predetermined region of the pressure bonding tool with a uniform film thickness by using a silk printing technique.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The thermocompression bonding tool of the present invention has a heat-resistant resin film of fluororesin or silicon resin at least on the surface of the crimping part.
A fluororesin is one in which all or only four hydrogen atoms of ethylene, which is a monomer in the molecular structure of polyethylene, become fluorine. Accordingly, the fluororesin includes, for example, PTFE (polytetrafluoroethylene).
In addition, the type of silicon resin is not particularly limited as long as it has heat resistance above the melting point (use temperature or higher) of resin or molten metal.
In this way, in a crimping tool having a heat-resistant and adhesive resin film made of a fluororesin formed on the crimping surface, a property of repelling the molten metal occurs on the crimping work surface. Or resin does not adhere to the crimping work surface.
The heat-resistant and adhesion-resistant resin film used in the present invention can be formed on a crimping tool base material by a silk printing technique used for manufacturing a printed wiring board or the like. A fluororesin can be obtained on the surface by subsequent heat drying and solidification. In addition, as a formation method of a heat-resistant adhesion-resistant resin film, the method of forming by vapor deposition other than the above silk printing technique may be used, and the method is not ask | required.
In addition, the base material of the crimping tool can be selected from various materials such as iron, stainless steel, silicon nitride, silicon carbide, aluminum nitride, aluminum oxide, and silicon oxide. The materials made are likewise suitable.
Next, processing is applied to the surface of the obtained heat and adhesion resistant resin coating. The processing is preferably grinding using a diamond grindstone or the like, and abrasive processing using ceramics or diamond abrasive grains. The flatness in that case is 0. 1μ or less is also possible. By this processing, the thermocompression bonding tool of the present invention can obtain sufficient flatness and can cope with more precise joining.
The thickness to be removed needs to be 0.05 μm or more. If it is less than 0.05 μm, the reactive group may remain on the surface.
In addition, the crimping tool in which the heat-resistant and anti-adhesive resin coating shown in the present invention is formed on the crimping surface has a property that the crimping work surface does not get wet with molten metal such as solder, and the molten metal adheres to the crimping work surface. Disappear.
Hereinafter, the present invention will be described in more detail by way of examples.
[0008]
【Example】
Example 1
A PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) film was formed as a heat-resistant and adhesion-resistant resin film on a flip-chip crimping tool made mainly of aluminum nitride by a silk printing technique. Then, a PFA film could be obtained on the surface by heating and drying in air at 50 ° C. to solidify. The thickness of the film was about 30 μm.
Next, processing was applied to the surface of the obtained heat and adhesion resistant resin coating. Processing was performed with a surface grinder having a cup-shaped diamond grindstone, and the grindstone # 1000 was used. When the film thickness was measured after grinding, it was about 20 μm.
When this crimping tool was mounted and operated on a flip-chip crimping tool and the temperature was raised to 250 ° C., it was hot-pressed, and because of its high flatness, good bonding could be achieved. The heat-bonded surface had an arithmetic average roughness Ra of 0.3 μm and a flatness of 0.02 μm with respect to the size of 8 mm × 8 mm of the pressure-bonded surface. Also, no solder welding occurred during use.
[0009]
(Comparative Example 1)
A crimping tool sample was prepared in the same manner as in Example 1, and the PFA film surface was not processed.
As a result of conducting the same experiment as in Example 1, the surface roughness was good with an arithmetic average roughness Ra of 1.0 μm, but the flatness was 22 μm, and pressure could not be evenly applied to the pressure-bonding surface. High precision crimping was not possible.
[0010]
(Comparative Example 2)
A sample in which a PFA film was not formed on the same sample as in Example 1 was prepared.
Due to the processing of the aluminum nitride part, the flatness was excellent at 0.05 μm, but the solder adhered to the crimping surface of the tool at the time of joining, and it was necessary to remove it frequently.
[0011]
(Comparative Example 3)
A crimping tool sample was prepared in the same manner as in Example 1, and the PFA film surface was processed on a milling machine equipped with a plurality of high-speed steel throwaway tips.
As a result of conducting the same experiment as in Example 1, the surface roughness was a rough surface with an arithmetic average roughness Ra of 12 μm. Pressure could not be applied evenly to the crimping surface, and as a result, highly precise crimping was not possible.
[0012]
(Example 2)
A vapor-deposited film of PTFE (polytetrafluoroethylene) was formed as a heat-resistant and welding-resistant resin film on a liquid crystal driver crimping tool mainly composed of silicon nitride. Thereafter, a PTFE film could be obtained on the surface by heating and drying in the air at 80 ° C. to solidify. The thickness of the film was about 10 μm.
Next, the obtained PTFE membrane was processed. Processing was performed by abrasive grinding with silicon carbide abrasive grains. When the film thickness was measured after grinding, it was about 5 μm.
When this crimping tool is mounted as a crimping tool for liquid crystal drivers and the temperature is raised to 265 ° C., the liquid crystal driver and the glass substrate are pressure-bonded by soldering between them. Can be joined. The surface roughness was as good as arithmetic average roughness Ra 0.6 μm, and the flatness was as good as 2.0 μm with respect to the size of 50 mm × 3 mm of the pressure-bonding surface.
No PTFE welding occurred during use.
[0013]
(Example 3)
A vapor-deposited film of silicon resin was formed as a heat-resistant and adhesive-resistant resin film on a pressure bonding tool for attaching ACF (anisotropic conductive film) using silicon nitride as a main material. Then, a silicon resin film could be obtained on the surface by heating and drying in the air at 50 ° C. to solidify. The thickness of the film was about 10 μm.
Next, the obtained silicon resin film was processed. Processing was performed by abrasive grinding with silicon carbide abrasive grains. When the film thickness was measured after grinding, it was about 5 μm.
This crimping tool is installed as a crimping tool for attaching ACF to a glass substrate. When the temperature is raised to 200 ° C., the ACF is melted and thermocompression bonded to the glass substrate. Good bonding could be performed. The flatness was 2.5 μm with respect to the size of 50 mm × 3 mm of the crimping surface. The arithmetic average roughness was as good as Ra 0.02 μm, and no ACF was welded to the crimping tool.
[0014]
【The invention's effect】
As described above in detail, according to the thermocompression bonding tool according to the present invention, the flatness is extremely high, precise bonding is possible, and compared with the conventional thermocompression bonding tool having a fluororesin coating. However, since the molten metal or resin does not adhere to the crimping work surface, the parallelism between the crimping work surface and the semiconductor element is good, the pressing force acts uniformly, and the heat-melt adhesion can be stabilized.
This technique is particularly suitable for bonding a flip chip to a substrate, ACF pressure bonding, liquid crystal driver bonding, and the like.

Claims (2)

And crimping surface for heat pressing the part, the thermocompression bonding tool having a heating portion for heating the bonding surface,
It has a film of either heat-resistant and adhesive-resistant fluorine resin or silicon resin from which the layer having an adhesive reactive group on the surface is removed on its pressure-bonding surface,
A tool for thermocompression bonding, wherein the film has an arithmetic average surface roughness Ra of 10 μm or less. After heat-resistant and adhesive fluorine resin or silicon resin is coated on the crimping surface of a thermocompression bonding tool having a crimping surface for crimping a component and a heating part for heating the crimping surface, surface grinding or surface polishing The surface layer is removed by at least 0.05 μm or more, and the arithmetic average surface roughness is Ra 10 μm or less.
more than