JPH0373588A - Mold release film for manufacturing printed wiring board and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve rigidity of a film by manufacturing a mold release film from uniaxially oriented PMP film. CONSTITUTION:PMP contains polymer which mainly contains single polymer of 4-methyl-1-pentene or 4-methyl-1-pentene as a main ingredient. A PMP film melted and extruded through a T die by an extruder 1 is cooled to about 80 deg.C by a cooling roll 2, and supplied to elongation rolls 4, 4' in a state that it is heated to about 170 deg.C by heating rolls 3. ln this case, the rotating speed of the elongating roll is regulated to uniaxially orient it to 2.5 to 6 times or desirably 4 to 5 times, it is cut in a predetermined length by a cutter as a film product. Thus, a PMP film having excellent rigidity can be manufactured.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a release film for manufacturing printed wiring boards and a method for manufacturing the same.
The present invention relates to a release film for producing printed wiring boards with excellent rigidity, which is obtained by uniaxially stretching a film of methyl-1-pentene (hereinafter referred to as PMP), and a method for producing the same.

(Conventional technology) In recent years, electronic 11m! ! It is well known that printed wiring boards are increasingly being used to meet the demands for higher precision, higher density, and higher reliability as the degree of integration of ICs increases with the rapid advancement of i. It is being These printed wiring boards include single-sided printed wiring boards, double-sided printed wiring boards, multilayer printed wiring boards, and flexible printed wiring boards, but among them, three or more layers of conductors are integrated with an insulating layer placed between them, The fields of application of multilayer printed wiring boards are expanding because they can connect arbitrary conductor layers to each other and to connect leads of mounted electronic components to arbitrary conductor layers.

This multilayer printed wiring board has a pair of single-sided or double-sided steel-bonded laminates as the outer layer, and on the inside there is one or more inner layers of circuit boards, epoxy resin, unsaturated polyester resin, etc.! 7) Stack these alternately through prepreg:! It is made by holding the prepreg between tools and curing the prepreg with a Luth hot plate through a cushioning material to form an integrated τ1.1. In manufacturing, prepregs placed on copper foil are integrated by heating and pressing, but the body laminates are not made one by one, but multiple sheets can be press-formed at the same time. It is being said. At this time, each body-attached laminate is formed by inserting a mold release sheet in between, and after molding, the female sheet is peeled off to obtain a body-attached laminate one by one.

As the release sheet, a film or sheet made of a material such as polytetrafluoroethylene, acetate, polypropylene, cellophane, etc., which does not melt due to the heat during molding of the body-attached laminate has been used. However, these release films have low rigidity, so-called film stiffness, so the film softens or wrinkles when heated to about 180 degrees Celsius during molding of the body laminate, making it difficult to achieve excellent dimensional accuracy. There was a problem in that it was difficult to mold the body laminate in a stable state.

Under these circumstances, in recent years, it has been proposed that PMP film be used as a release film during the manufacture of the above-mentioned body-attached laminates due to its excellent heat resistance (Japanese Unexamined Patent Application Publication No. 1983-1999). Publication No. 70653, Special Publication No. 58-159
Publication No. 52).

Since this PMP has a high melting point of 235° C., it exhibits excellent heat resistance even in the molding of a body clad laminate at about 180° C., and is evaluated as an H-type sheet with few of the above-mentioned defects.

However, in recent years, there has been a trend in which high-quality multilayer printed wiring boards are required to increase wiring speed and improve reliability, and the body-attached laminates used to manufacture such printed wiring boards naturally The conditions for heating and pressing during manufacturing have become stricter, and it is becoming increasingly difficult to say that the rigidity of the PMP film alone is sufficient.

(Objective of the Invention) Therefore, an object of the present invention is to provide a release film that is even more rigid than the conventional PMP release film.

Still another object of the present invention is to provide a method for manufacturing a PMP film with excellent rigidity.

(Means for Solving the Problems) The present invention has been proposed to achieve the above objects, and is characterized by: - a release film for producing a printed cotton board made of an axially stretched PMP film; .

Further, the release film of the present invention can be obtained by uniaxially stretching a PMP film melt-extruded from an extruder at a stretching ratio of 2.5 to 6 times.

The release film of the present invention exhibits an excellent breaking strength in the machine direction of %700 to 1500 kg/cm" obtained by uniaxially stretching a melt-extruded PMP film at a specific stretching ratio, 150 to 40
Compared to unstretched PMP film, which has a breaking strength in the machine direction of approximately 0 kg/am, it is much stronger and can be laminated to the body without wrinkles even under severe pressing conditions. The plate can be released from the mold, and a body-attached laminate with excellent dimensional accuracy can be obtained.

(Description of preferred embodiments) PMP in the present invention is a homopolymer of 4-methyl-1-pentene, or a homopolymer of 4-methyl-1-pentene and other α-olefins, such as ethylene, propylene, 1-
Butene, ■-hexene, l-octene, 1-decene, l
- 2 to 2 carbon atoms such as tetradecene, 1-octadecene, etc.
copolymer with α-olefin of 0 and usually 4-methyl-1
- It is a polymer mainly composed of 4-methyl-1-pentene, which contains 85 mol% or more of pentene. Poly 4-methyl-i-
The melt flow rate of pentene (load = 5 kg, temperature: 260°C) is preferably 0.5 to 250 g/10
■It is within the range of in. Melt flow rate is 0.
If it is less than 5 g/l 0 w1n, the melt viscosity is high and the moldability is poor, and the melt flow rate is 200 g/l 0.
Those exceeding sin have low melt viscosity and poor moldability, and also have low mechanical strength.

In addition, PMP may include any known substances that are incorporated into polyolefins, such as heat-resistant stabilizers, weather-resistant stabilizers, rust inhibitors, copper damage-resistant stabilizers, antistatic + L agents, etc., to the extent that they do not impair the purpose of the present invention. Various additives can be added to PMP.
In order to improve the release properties of the film,
A small amount of silicone oil can also be added.

A first example showing an example of the process of manufacturing the H-type film of the present invention.
In the figure, the PMP film melt extruded from the extruder 1 through the T-die is heated to about 80°C by the cooling roll 2.
After being cooled down to a temperature of about 170 mm, the heating roll 3
It is supplied to the stretching rolls 4, 4' in a heated state to about .degree. In the present invention, by adjusting the rotation speed of the stretching roll, the
After uniaxial stretching, the film is cut into a predetermined length using a cutter to produce a product.

A PMP film having a thickness of 20μ or more is usually obtained by melt extrusion, but the release film in the present invention also includes a film with a thickness of 10 to 300μ, with a thickness of 25 to 70μ being particularly preferred. used. If the film is thinner than 10μ, it may not have sufficient strength during peeling, and if it is thicker than 300μ,
There is no particular advantage and it is economically disadvantageous.

The release film of the present invention can be obtained by the method described above, but both surfaces of the film can be roughened by sandblasting, embossing, etc. to increase the surface area of the film.

Figures 2 to 4 are for explaining the process of manufacturing a multilayer printed wiring board using the release film of the present invention, and Figure 2 shows the layer structure of the body-attached counterfeit board before pressing. FIG. A copper foil 14' is applied to the press plate 11' l: via a cushion material 12' and a press hot plate 13'.
A prepreg 15' is placed on the copper foil, which is integrated by heating and curing to form a shell laminate. The prepreg 15 and the copper foil 14 are placed on the prepreg 15' with a release sheet 16 interposed therebetween in the opposite direction to the E layer structure, and then placed on the press plate through the press heating plate 13 and the cushion material 12. By heating and pressurizing in steps 11 and 11', two single-sided body-bonded laminates in which the copper foil and prepreg are integrated are formed. FIG. 3 shows a state in which the body-attached laminate and the release film have been peeled off.

Prepreg usually includes various types of glass cloth such as roving cloth, cloth, chopped mat, and surfacing mat, synthetic fiber cloth such as vinylon, Tetoron, and acrylic, cotton cloth, linen cloth, felt, kraft paper, cotton paper, and carbon fiber paper. , refers to a material obtained by impregnating a base material such as semi-carbon fiber cloth with a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, or a cyanate ester resin, and converting it into a B-stage.

Next, the cured resin surfaces of the body-attached laminates 17° and 17' thus obtained are integrated by heating and pressing via a prepreg 15'' made of the same synthetic resin as the cured resin. It is a sectional view showing the state.At this time, some of the epoxy resin and unsaturated polyester used as prepreg melt due to the heat during pressurization and flow out, and the press hot plate 13, 13' and the press plate 11 .11', etc., and may harden as it is, and in this case, the function of the press hot plate or press plate will be significantly impaired.The release film of the present invention eliminates such inconveniences. In other words, the release film of the present invention cut into slightly larger pieces, press hot plate 1
3. Insert it between 13' and copper foil 14, 14' (
If the resin is peeled off after curing (not shown), it is possible to prevent the press hot plate and the press plate from being contaminated by the flowed out and cured resin.

Heating for forming the body-attached laminate and the multilayer printed wiring board was carried out at a temperature of approximately $180°C.

The pressure is 5 kg/cm"-Gt' l After preheating for 5 to 30 minutes, the pressure is 30 to 6 at 30 kg/cs+"G.
Although pressing is carried out for 0 minutes, the release film of the present invention can sufficiently withstand heating and pressurization at 180° C. and up to approximately SO kg/c-G without deformation.

The greatest feature of the release film of the present invention is that the melt-extruded PMP film is uniaxially stretched at a stretching ratio of 2.5 to 6 times. If the stretching ratio is less than 2.5 times, the improvement in rigidity will not be significant and the film will not be stretched uniformly, and if the stretching ratio is more than 6 times, although the rigidity will be improved, the film may break. , it will not be possible to obtain the desired product. Note that the temperature of the film during stretching is 130 to 200°C, preferably 150 to 170°C; at other temperatures, stretching at the above-mentioned stretching ratio becomes difficult.

As mentioned above, the mold release film of the present invention has extremely high rigidity and exhibits excellent mold release properties without wrinkles on the film surface even under severe heating and pressure during press molding. Therefore, it is fully applicable to the molding of inner layer circuit boards using high temperature and high pressure, which has recently become a requirement for high heat resistance in order to increase wiring speed and improve reliability.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

Example! 90 with a cast die using PMP with a melt flow rate of 25 measured at 250 °C and 5 kg load.
A PMP sheet with a thickness of 0.2 mm was extruded using a +mmφ single screw extruder. Extruder temperature is 300℃, die temperature is 2
The temperature was 80°C. The extruded sheet is cooled and solidified with a chill roll at 80°C, and then preheated with a preheating roll at 170°C. The preheated sheet is taken at a take-up speed of 20
It was stretched 5 times using m/win stretching rolls. Using the uniaxially stretched PMP film thus formed, a 30 μm copper foil and a 0.8+am glass fiber-containing revoxy prepreg (resin content = 52%) was press-molded in the configuration shown in FIG. 5.

The press was first heated at 130°C for 45 minutes at a press pressure of 15 kg/c-, then at a press pressure of 40 kg/am''.
Heating was performed at 180° C. for 1 hour to complete curing of the epoxy prepreg. This molded article was cooled to room temperature, and the molded article was peeled, and its peelability and appearance were examined. As a result, the mold releasability after pressing was good, and the appearance was also good.

Example 2 A film formed by the method of Example 1 was pressed with the layer structure shown in FIG. 6, and its releasability was evaluated.

Blackened steel foil was used as the copper foil.

The press was initially pressurized at 13 kg/am' with a press pressure of 15 kg/am'.
Heated at 0℃ for 45 minutes and then pressed at a pressure of 40kg/ci.
The molded product was heated at 180°C for 1 hour to complete the curing of the epoxy prepreg.The molded product was cooled to room temperature, and the molded product was peeled off to examine its releasability.As a result, after pressing, The female type was good and the appearance was also good.

Comparative Example 1 90 with cast die using PMP of Example 1
- A PMP film was extruded using a φ single screw extruder.

The temperature conditions of the extruder were as follows: cylinder temperature was 300°C, die temperature was 280°C, and 50 u (DT-die film was extruded). The extruded film was cooled and solidified with a chill roll at 80°C.

Using the T-die film thus formed, press molding was carried out in the same manner as in Example 1, and the mold releasability and appearance were examined. As a result, the film was torn during peeling and had poor mold releasability. In addition, wrinkles were observed on the peeled epoxy surface.

Comparative Example 2 Press molding was performed using the PMP T-die film molded in Comparative Example 1 with the same configuration as in Example 2, and its mold releasability was examined. As a result, the PMP film completely bit into the rough surface of the blackened copper foil and could not be peeled off.

[Brief explanation of drawings]

FIG. 1 is a diagonal diagram showing the manufacturing apparatus for a release film of the present invention, FIGS. 2 to 4 are cross-sectional views showing the manufacturing process of a multilayer printed wiring board, and FIGS. FIG. 3 is a cross-sectional view showing the layer structure. 1.-Extruder, 2.--cooling roll, 3.--heating roll, 4.4'--stretching roll, 5.--cutter 11.1
1'...Press plate, 12.12'...-Cushion material, 13.13'...-Brace heating plate, 14°14'...
Copper foil, 15.15'...Prepreg, 15~...Adhesive prepreg, 16.16'...Release film, 1
7.17'...Inner layer circuit board.

Claims (2)

[Claims] (1) A release film for producing printed wiring boards made of a uniaxially stretched poly-4-methyl-1-pentene film. (2) Poly-4-methyl- melt-extruded from an extruder
1. A method for producing a release film for producing printed wiring boards, which comprises uniaxially stretching a 1-pentene film at a stretching ratio of 2.5 to 6 times.