JPS5921199B2 - Manufacturing method of resin film substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin film substrate used for a substrate such as an electronic circuit.

Recently, when mounting parts such as semiconductor elements to form an electronic circuit, a technology that uses a resin film on a board on which wiring has been formed,
And excellent materials such as polyimide films have been developed as resin films for the same.

If you try to use this resin film as a board to mount components at high density, fine processing such as wiring patterns and contact windows between multilayer wiring will be required.In particular, if there are many through holes, the thinner the resin film is, the better. A fine and accurate substrate can be obtained. Also, for example, polyimide film is expensive, so
In order to reduce material costs, it is desirable to use something as thin as possible. However, when a very thin resin film is used, there are problems with the resin film's smoothness and bending during processing, and difficulty in handling. It was becoming a hindrance. The present invention provides a method for manufacturing a resin film substrate that enables fine processing by bonding a metal frame to an extremely thin resin film.One example of the method will be explained below along with the manufacturing process and drawings. do.

Figures 1A to 2A show the second diagram showing the manufacturing process of the resin film substrate.
It is an enlarged cross-sectional view taken along the line A-A in FIG. FIG. 1A shows a resin film, where 1 is a resin film base and 2 is an adhesive layer. This resin film substrate is preferably a heat-resistant and flexible resin film, such as a polyimide resin film, and in the present invention, the effect is particularly remarkable when using a very thin film of 50 μm or less. . Adhesive layer 2 has 2.
Although FEP resin having a thickness of approximately 5 μm to 25 μm is used, an equivalent epoxy resin or the like may be used. Reference numeral 3 is a metal frame made of stainless steel, nickel, or the like, formed in a lattice shape, and is thermocompression bonded to the adhesive layer 2 at about 300° C., and is fixed integrally with the resin film as shown in FIG. 1A.

At this time, resin films generally have a larger coefficient of expansion than metals. That is, since the temperature is quite high at the moment of adhesion, the resin film base 1 will bend. This deflection decreases as the temperature returns to room temperature, resulting in a taut, smooth film surface. In the state shown in Fig. 1A with the metal frame 3 bonded, the mechanical strength is high, but if you try to form contact windows or through holes on the resin film base 1 as it is, the following problems will occur. arise. During this processing, for example, when forming a mask by vapor deposition, it is necessary to raise the temperature to improve the adhesion between the metal vapor deposited film and the resin film, and when plasma etching is performed, the reaction heat increases. As a result, the temperature of the resin film base 1 to which the metal frame 3 is bonded rises, and deflection occurs again due to the difference in expansion coefficient between the resin film base 1 and the metal frame 3. At this time, the adhesion between the master plate and the resin film substrate 1 deteriorates, making it impossible to perform processing faithful to the pattern of the mask plate. Particularly when the mask plate is used as a substrate for a high-density device, the pattern of the mask plate becomes very fine, and the bending of the resin film base 1 due to temperature becomes an extremely important problem. Steps c and 1 in FIG. 1 are steps taken with this in mind, in which a metal coating is formed in advance when processing the resin film substrate 1. Reference numeral 4 denotes a first metal film thinly formed on the surface of the adhesive layer 2 of the resin film by vapor deposition or electroless plating.

Since this first metal film 4 is finally removed, it does not necessarily require strong adhesive strength and can be formed in a smooth state without raising the temperature of the resin film base 1. Next, a second metal film 5 is formed by electrolytic plating using a metal material having a coefficient of expansion comparable to that of the metal frame 3. This second metal film 5 has the purpose of imparting appropriate strength to the surface of the resin film base 1, and its film thickness is appropriately adjusted depending on the thickness of the resin film base 1. 6 is a mask board, for example 7
It has a mask hole for forming a through hole such as.

When this mask plate 6 is placed on the metal frame 3 or the surface of the resin film substrate 1 without the metal film as shown in FIG. Etching holes 8 are formed in the resin film substrate 1. During this plasma etching process, the temperature of the resin film base 1 rises, but the expansion coefficients of the first and second metal films 4 and 5 formed on the other surfaces are about the same as that of the metal frame 3. Since the resin film substrate 1 has a high degree of accuracy, bending does not occur in the resin film base 1, and highly accurate processing is possible. After the micromachining of the resin film base 1 is completed, the first step described above is completed.
Then, the second metal films 4 and 5 are removed by chemical etching to obtain a resin film substrate 5 having a shape as shown in FIG. When attaching a semiconductor element to the resin film substrate, it is convenient to fix it by thermocompression bonding to the adhesive layer 2 from the side where the metal frame 3 is located.

Further, the resin film substrate of this embodiment on which semiconductor elements and passive components are attached may be used as is with the metal frame 3, or may be used separately from the metal frame 3. Note that if a scale 9 as shown in FIG. 2 is provided on the metal frame 3, positioning when attaching or separating parts will be facilitated. In the resin film substrate manufactured by the manufacturing method of this embodiment, the resin film substrate 1 may be bent due to thermal expansion during processing such as vapor deposition or plasma etching, especially when high precision is required such as through-hole formation. Therefore, accurate machining is possible. Furthermore, since the metal frame 3 has the function of reinforcing the resin film base 1, it has become possible to make the thickness of the resin film base 1 extremely thin in order to perform accurate processing. Furthermore, it is possible to reduce material costs by using a thin resin film, and to facilitate handling by installing the metal frame 3. Note that if the semiconductor element is adhesively fixed to the adhesive layer 2, the thickness of the semiconductor element is about 200 .mu., while damage to the semiconductor element can be reduced by making the metal frame 3 about 500 .mu. thick. As described above, the present invention involves bonding a metal frame and a resin film having an adhesive layer, forming a metal coating on the side where the adhesive layer is, and applying the resin film from the opposite side using a mask. By removing the metal coating after processing and forming a resin film substrate, it is possible to perform high-precision microfabrication for high density, and to reduce material costs.This is an industrially superior resin film substrate. and its manufacturing method.

[Brief explanation of the drawing]

FIGS. 1A to 1H show an embodiment of the resin film substrate of the present invention and its manufacturing method, and are enlarged cross-sectional views of the steps, and FIG. 2 is a plan view of the resin film substrate. DESCRIPTION OF SYMBOLS 1... Resin film substrate, 2... Adhesive layer, 3... Metal frame, 4... First metal film, 5... -Second metal film, 6...Mask plate, 8...Etching hole.

Claims (1)

[Claims] 1 A step of adhering a metal frame and a thin resin film having an adhesive layer on one side, a step of forming a metal coating for preventing deflection on both sides with the adhesive layer, and a step of attaching the mask from the opposite side to the above-mentioned side. 1. A method for manufacturing a resin film substrate, comprising the steps of: processing a resin film using the metal film; and removing the metal film for preventing deflection.