JPH02205332A - Film carrier and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a film carrier having a merit as a low dielectric constant, a fast signal transmission rate and the possibility of usage in a high-frequency region, by using fluoroplastics as an insulating layer and a bonding layer and bonding three layers constituted including a conductor layer through a thermocompression bonding system in a single operation. CONSTITUTION:Glass cloth is impregnated with fluoroplastics to form an insulating layer 2 as a base, and a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer is selected as a bonding layer 4, placed onto one surface of the insulating layer 2, thermocompression-bonded lightly and fixed temporarily. A device hole 5 and sprocket holes 6 are shaped, electrolytic copper foils are selected as conductive layers 3, and the foils are laminated onto the insulating layer 2 with the bonding layer 4. The foils are thermocompression-bonded for thirty min at a pressure of 30kg at a temperature of 370 deg.C for laminating. Accordingly, since the dielectric constant of a film carrier body manufactured is reduced, the rate of transmission is accelerated, and the film carrier can be used in a division such as a computer employed for arithmetic operation at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method of manufacturing a film carrier used for mounting integrated circuit chips such as ICs and LSIs.

<Prior art> As shown in Fig. 3, a conventional film carrier coats a liquid adhesive 4 on one side of an insulating layer 2 made of a polyimide film or a polyester film, and then laminates a copper foil as a conductive layer 3. As shown in FIG. 4, a conductive layer 3 is formed on one side of an insulating layer 2 made of the same material as the one described above by plating, vacuum deposition, etc. Two types of two-layer systems have been devised, in which the insulating layer 2 is formed by coating liquid polyimide on the insulating layer 2.

<Problems to be Solved by the Invention> Conventional film carriers had the following problems. In the case of the Φ three-layer type, there was a problem in heat resistance. That is, even if heat-resistant polyimide is used for the insulating layer 2, an epoxy-based material must be used for the adhesive layer 4, which plays the role of adhesion to the copper foil that is the conductive layer 3. Gender is 1
Since the temperature is as low as 50.degree. C., for example, when a solder bonding method is used to connect to a circuit board, heat of about 260.degree. C. is applied, so that only a few seconds of work time is allowed. This thing is
This was a constraint when carrying out such work.

In addition, when coating the insulating layer 2 with a liquid adhesive made of different materials, it is difficult to expect chemical bonding, so it is necessary to rely on the physical anchor effect to improve the adhesive strength. The manufacturing process requires time-consuming steps such as graining 9 of the insulating layer 2 by means such as liquid honing.

On the other hand, unlike the three-layer type, the two-layer type does not have the adhesive layer 4, so poor solder heat resistance does not occur.
There was a problem that the manufacturing process was frequent. That is,
In the case of a two-layer type, as described above, due to the structure, it is not possible to form the device holes 5 and sprocket holes 6 in the insulating layer 2 in advance by a simple method such as press punching, and the insulating layer 2 is formed by photolithography. It had to be formed into a pattern. In this case, the manufacturing method was quite complicated because it required two photolithography steps in addition to the patterning of the conductive layer 3.

Furthermore, because conventional film carriers use polyimide or polyester as an insulating layer, their dielectric constants are around 3.5 and 3.2 (IMHz), respectively. This caused inconveniences such as the department not being able to use it.

Furthermore, when polyester is used as the insulating layer 2, the heat resistance is even lower, and its applications such as inexpensive calculators are limited.

Means for Solving the Problems> An object of the present invention is to provide heat resistance, eliminate the graining process of the insulating layer 2 that was necessary in the three-layer method, and eliminate the need for a graining step for the insulating layer 2, which was required in the three-layer method. The purpose of the present invention is to provide a film carrier that can be produced by a simple manufacturing method, such as requiring only one photolithography process instead of two. Specifically, the object is to provide a manufacturing method in which a fluororesin is used for the insulating layer and the adhesive layer, and three layers including the conductor layer are bonded together by thermocompression bonding.

Function> Insulating layer 2 which is one of the characteristics of the film carrier of the present invention
The point of using a fluororesin will be explained below.

Information-related equipment such as computers is becoming larger in capacity, and it is desired to increase the signal propagation speed. The signal propagation velocity (V) is V - K x C/(T' - (K constant, C
- the speed of light, ε = dielectric constant), so the smaller the dielectric constant, the faster the propagation speed, which allows for higher-speed calculations. Fluororesin is a resin with the lowest dielectric constant of 2.2 to 2.5, and is most suitable as an insulating layer for this purpose. Polyimide and polyester, which are used for conventional film carriers, each have a dielectric constant of 3.5.
, is around 3.2, and comparing these, there is a possibility of increasing the signal propagation speed by 1.1 to 1.3 times in case of fluororesin. In addition, in the communication field, 12GH is used for satellite broadcasting.
Two bands of high frequency are used, and in this area, if polyimide with a high dielectric constant is used, it may generate noise and is not suitable.However, fluorine-based resin with a low dielectric constant has no problem, and is used as a converter for BS antennas. It can be used for etc.

The present invention will be compared with a conventional three-layer film carrier. Conventionally, as mentioned above, liquid adhesive was coated on the insulation N2, but in order to increase the adhesive strength, the surface of the insulation N2 had to be grained by means such as liquid honing. .

If a fluorine-based resin is used as the insulating layer 2 of the present invention and a sheet-like fluorine-based resin is used as the adhesive layer 4, since both are thermoplastic materials, if they are thermocompressed at a temperature higher than their melting point, they will melt and bond together. things are possible. Therefore, the step of milling the surface of the insulation N2 as in the conventional method is not necessary.

Examples of the fluororesin used in the present invention include polytetrafluoroethylene (hereinafter abbreviated as PTFE), polychlorotriolethylene, polyvinylidene fluoride, polyvinyl fluoride, and a copolymer of tetrafluoroethylene and hexafluoropropylene. However, PTFB is preferable in terms of heat resistance.

Possible forms of the insulating layer 2 include a single fluororesin, a glass cloth impregnated with it, and a structure containing closed cells. The appropriate thickness is 10 to 250 μm. In addition, as the adhesive layer 4, a tetrafluoroethylene-perfluoroalkali vinyl ether copolymer (hereinafter referred to as PF
(abbreviated as ^) is desirable.

The material of the conductive layer 3 is preferably copper, aluminum, nickel, iron-nickel alloy, stainless steel, silver, solder, gold, etc., and the thickness is suitably 5 to 200 μm.

The film carrier of the present invention and its manufacturing method will be described below using Examples.

<Example> 35m glass cloth (Arisawa Seisakusho 10BOA, thickness 8
0 μm) was impregnated with a fluororesin (PTF [!Fluon AD-1, manufactured by Asahi Glass ■) to form the base insulation N2.

Thereafter, PFA (manufactured by Daikin Industries, Ltd., thickness: 25 μm) was selected as the adhesive layer 4, and was placed on one side of the insulating layer 2 and lightly thermocompressed for temporary fixing. Furthermore, a device hole 5 and a sprocket hole 6 were formed using a press punching method according to wide type specifications (26.996+as in effect). Further, as the conductive layer 3, electrolytic copper foil (manufactured by Nikko Gould ■, JTC
A foil having a thickness of 35 μm and a width of 26.0 am) was selected and laminated with the insulating layer 2 with the adhesive layer 4 described above. For lamination, a vacuum press machine is used, and the temperature is set to PTF.
I! The temperature was set at 370°C, which is above the melting point (327"c) of 2.0 kg
/cta, and the adhesive strength was comparable to that of conventional polyimide bases. Also, the dielectric constant is 2.5
Met.

Thereafter, the copper foil serving as the conductive layer 3 was patterned in the same process as the conventional film carrier 1. That is,
Negative resist PM manufactured by Tokyo Ohka Kogyo ■! Using R,
After forming a resist, the copper foil was etched using a cupric chloride etchant to form inner leads 7 (pitch 160βm, flat medium 80/7m, number of pins 250). Thereafter, a solder resist was printed using the screen printing g++ method except for the tips of the inner leads 7 and outer leads 8. (The ink was CCR240GS manufactured by Asahi Chemical Research Institute) Furthermore, 9:1 solder plating (thickness: 7 μm) was applied to the portion where the solder resist was not formed, and a film carrier I was completed.

The film carrier 1 in which the insulating llI2 of the present invention is based on a fluororesin, manufactured in this manner, is used as a part of a converter for a BS antenna, and easily passes soldering heat resistance (260°C, 30 μm) during mounting. However, the product was in good condition, meeting all required specifications including reliability.

<Effects of the Invention> As described above, the film carrier of the present invention using a fluororesin as an insulating layer has high heat resistance, and also has advantages such as being able to shorten the manufacturing process. I was able to do something.

In addition, by using the film carrier of the present invention, the advantage of its low dielectric constant, that is, the signal propagation speed is high,
Since it can be used in the high frequency M range (for example, 12 GIIz or higher), it has become possible to use it in the fields of supercomputers and satellite broadcasting, which conventional film carriers could not handle.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a part of a tape carrier according to the present invention. FIG. 2 is a schematic cross-sectional view showing a part of a tape carrier according to the present invention. FIG. 3 is a schematic cross-sectional view showing a part of a conventional three-layer tape carrier. Figure 4: Schematic cross-sectional view showing part of a conventional two-layer tape carrier 1. Tape carrier 2. Insulating layer 3. Conductive layer 4, adhesive layer 5. Device hole 6, sprocket hole 7. Inner lead 8, Aether lead 9. Patent filed for Sunamokuro Kazuo Suzuki, Representative of Toppan Printing Co., Ltd.

Claims (2)

[Claims] (1) A film carrier in which the insulating layer and the adhesive layer are made of a fluororesin, and the insulating layer, the adhesive layer, and the conductive layer are bonded together by thermocompression bonding. (2) Temporarily adhere a film-like adhesive layer to the insulating layer, form a predetermined hole using a press punching method, then laminate a conductive layer using a thermocompression method, and form a predetermined pattern using a photolithography method. The method for producing a film carrier according to claim 1.