JP2790330B2 - Release film for manufacturing printed wiring board and method for manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a release film for producing a printed wiring board and a method for producing the same, and more particularly, to poly-4-methyl-1-pentene ( The present invention relates to a release film for producing a printed wiring board having excellent rigidity, which is obtained by uniaxially stretching a film of PMP at a predetermined stretching ratio, and a method for producing the same.

(Prior art) In recent years, with the rapid progress of electronic devices, as the degree of integration of ICs increases, the use of printed wiring boards is increasing in order to meet the demand for higher precision, higher density, and higher reliability. It is well known that this has been done. As this printed wiring board, there are a single-sided printed wiring board, a double-sided printed wiring board, a multilayer printed wiring board, and a flexible printed wiring board. Among them, an insulating layer is integrated in the middle of three or more conductors, and integrated. The field of application of the multilayer printed wiring board is widespread in that any conductor layers can be connected with each other and between leads of electronic components to be mounted and arbitrary conductor layers.

This multilayer printed wiring board is formed by alternately stacking a pair of single-sided or double-sided copper-clad laminates as an outer layer board, and inside one or more inner-layer circuit boards or prepregs such as epoxy resin or unsaturated polyester resin inside. The prepreg is manufactured by clamping these with a jig, curing the prepreg with a hot plate press through a cushion material, and integrating them. By the way, in the production of a copper-clad laminate performed prior to the production of a multilayer printed wiring board, a prepreg placed on a copper foil is integrated by heating and pressing, but one copper-clad laminate is used. Rather than being made one by one, a plurality of sheets are simultaneously pressed. At that time, each of the copper-clad laminates is obtained by inserting a release sheet in the middle thereof, peeling the release sheet after molding, and obtaining a copper-clad laminate one by one.

As the release sheet, a film or sheet made of a material that does not melt by heat at the time of forming a copper-clad laminate, such as polytetrafluoroethylene, acetate, polypropylene, and cellophane, has been used. However, these release films have low stiffness and the so-called stiffness of the film is weak, so that the film is softened or wrinkled by heating at about 180 ° C. during the formation of the copper-clad laminate, and has excellent dimensional accuracy. There is a problem that it is difficult to form a copper-clad laminate in a stable state.

Under these circumstances, it has been proposed to use a PMP film as a release film in the production of the copper-clad laminate, because of its excellent heat resistance in recent years. No. 70653, Japanese Patent Publication No. 58-15952).

Since this PMP has a high melting point of 235 ° C., it exhibits excellent heat resistance even in the formation of a copper-clad laminate at about 180 ° C., and is evaluated as a release sheet having few defects.

However, in recent years, there has been a tendency for high-quality multilayer printed wiring boards to be required in order to increase wiring speed and improve reliability, and copper-clad laminates used in the manufacture of such printed wiring boards are naturally The conditions of heating and pressurizing during production have become severe, and it is becoming difficult for PMP films alone to have sufficient rigidity.

(Object of the Invention) It is an object of the present invention to provide a release film that is more rigid than a conventional PMP release film.

Still another object of the present invention is to provide a method for producing a rigid PMP film.

(Means for Solving the Problems) The present invention has been proposed to achieve the above object, and has been proposed for producing a printed wiring board made of a PMP film uniaxially stretched at a stretching ratio of 2.5 to 6 times. It features a mold film.

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.

Release film of the present invention, a PMP films melt extruded was example by uniaxial stretching at a specific stretch ratio, which shows a breaking strength in the machine direction which is superior in that 700 to 1500 kg / cm ^2, 150 or than the unstretched PMP film exhibiting a breaking strength of 400 kg / cm ² approximately in the machine direction,
The release of the copper-clad laminate is achieved without much wrinkling of the film even under severe pressing conditions under severe press conditions, and a copper-clad 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 4-methyl-1-pentene and another α-olefin, for example, ethylene, propylene, 1-olefin.
Butene, 1-hexene, 1-octene, 1-decene, 1
-C2-C20 such as tetradecene, 1-octadecene, etc.
Is a copolymer with α-olefin, usually 4-methyl-1-
It is a polymer mainly composed of 4-methyl-1-pentene containing pentene of 85 mol% or more. Melt flow rate of poly-4-methyl-1-pentene (load: 5kg, temperature: 260 ° C)
Is preferably in the range of 0.5 to 250 g / 10 min. If the melt flow rate is less than 0.5 g / 10 min, the melt viscosity is high and the moldability is poor, and the melt flow rate is 200 g / 1 min.
Those exceeding 0 min have low melt viscosity and poor moldability, and low mechanical strength.

In addition, PMP is a heat-resistant stabilizer, a weather-resistant stabilizer, a rust preventive material, a copper damage-resistant stabilizer, a known anti-static agent which is blended with a polyolefin such as an antistatic agent, as long as the object of the present invention is not impaired. Various additives can be blended, and a small amount of silicone oil can be blended to further improve the releasability of the PMP film.

In FIG. 1 showing an example of a process for manufacturing a release film of the present invention, a PMP film melt-extruded from an extruder 1 through a T-die is cooled by a cooling roll 2 to about 80 ° C. 3 and supplied to the stretching rolls 4, 4 'while being heated to about 170.degree.
In the present invention, by adjusting the number of revolutions of the stretching roll, after performing uniaxial stretching to 2.5 to 6 times, preferably 4 to 5 times, a film of a predetermined length is cut by a cutter to obtain a product. .

PMP film is usually obtained by melt extrusion of a thickness of 20μ or more, as a release film in the present invention, also includes those having a thickness of 10 ~ 300μ,
Particularly, those having a size of 25 to 70 μm are preferably used. When the film is thinner than 10 μm, the strength at the time of peeling is not sufficient, and when the film is thicker than 300 μm, there is no particular advantage and it is economically disadvantageous.

The release film of the present invention is obtained by the above-mentioned method. However, both surfaces of the film may be roughened by sandblasting or embossing to increase the surface area of the film.

2 to 4 are diagrams for explaining a process of manufacturing a multilayer printed wiring board using the release film of the present invention, and FIG. 2 shows a layer configuration of a copper-clad laminate before pressing. FIG. On the pressing plate 11 ', cushion material 1
A copper foil 14 'is placed via 2' and a press hot plate 13 ', and a prepreg 15' is placed on the copper foil by heat curing to form a copper-clad laminate. On the prepreg 15 ′, a prepreg 15 and a copper foil 14 are placed via a release sheet 16 in a manner opposite to the above-mentioned layer configuration, and the prepreg 15, a pressing hot plate 13, , 1
By heating and pressing 1 ', two single-sided copper-clad laminates in which a copper foil and a prepreg are integrated are formed. FIG. 3 shows a state in which the copper-clad laminate and the release film have been peeled off.

The prepreg is usually, for example, a roving cloth,
Various glass cloth such as cloth, chopped mat, and facing mat, synthetic fiber cloth such as vinylon, tetron, acrylic, cotton cloth, linen, felt, kraft paper, cotton paper, carbon fiber paper, semi-carbon fiber cloth, etc. Impregnated with a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, and a cyanate ester resin;
Refers to a stage.

Next, the cured resin surfaces of the copper-clad laminates 17, 17 'thus obtained are integrated by heating and pressing via a prepreg 15' made of the same synthetic resin as the cured resin. FIG. 4 is a sectional view showing this state. At this time, some of the epoxy resin and unsaturated polyester used as the prepreg are melted by the heat at the time of pressurization and flow out, contaminating the press hot plates 13, 13 'and the press plates 11, 11', etc. It may be hardened, and in this case, the function of the hot plate or press plate is significantly impaired. The release film of the present invention is also used to prevent such inconvenience. That is, the release film of the present invention is cut to a slightly larger size, press hot plates 13, 13 'and copper foil 14,
If it is inserted between 14 '(not shown) and peeled off after curing, it is possible to prevent the hot press plate and the press plate from being contaminated by the resin that has flowed out and been cured.

Heating when forming the copper-clad laminate and the multilayer printed wiring board is usually performed at about 180 ° C., and the pressure is 5 kg / cm ^2.
G is preheated for 15 to 30 minutes and then pressed at 30 kg / cm ² · G for 30 to 60 minutes. The release film of the present invention has a temperature of 180 ° C. and 50 kg / cm ² · G. Can sufficiently withstand the heating and pressing 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. When the stretching ratio is 2.5 times or less, the rigidity is not so much improved, and the film is not stretched uniformly. When the stretching ratio is 6 times or more, although the rigidity is improved, the film may be stretched and cut. You will not be able to get the product. The temperature of the film at the time of stretching is 130 to 200 ° C., preferably 150 to 170 ° C. At other temperatures, it is difficult to perform stretching at the stretching ratio.

The release film of the present invention, as described above, has extremely excellent rigidity, and exhibits excellent release properties without being wrinkled on the film surface even under severe heating and pressurization during press molding. For this reason, it is possible to sufficiently cope with molding of an inner layer circuit board by high temperature and pressure due to a demand for high heat resistance in order to increase a wiring speed and improve reliability.

Hereinafter, the present invention will be described in detail with reference to examples.

Example 1 A 0.2 mm thick PMP sheet was extruded with a 90 mmφ single screw extruder having a cast die using a PMP having a melt flow rate of 25 measured at 250 ° C. under a load of 5 kg. The extruder temperature was 300 ° C and the die temperature was 280 ° C. The extruded sheet is cooled and solidified by a chill roll at 80 ° C, and then
Preheated by 170 ° C preheating roll. The preheated sheet was stretched 5 times by a stretching roll having a take-up speed of 20 m / min. Using the thus formed uniaxially stretched PMP film, a 30 μm copper foil and a 0.8 mm glass fiber-containing epoxy prepreg (resin content = 52%) were press-formed in the configuration shown in FIG.

The press was first heated at 130 ° C. for 45 minutes at a pressure of 15 kg / cm ² , and then for 1 hour at 180 ° C. at a pressure of 40 kg / cm ² to complete the curing of the epoxy prepreg. The molded product was cooled to room temperature, the molded product was peeled, and the peelability and appearance were examined. As a result, the release property after pressing was good, and the appearance was also good.

Example 2 The film formed by the method of Example 1 was pressed with the layer configuration shown in FIG. 6 to evaluate the releasability. A blackened copper foil was used as the copper foil.

The press was first heated at 130 ° C. for 45 minutes at a pressure of 15 kg / cm ² , and then for 1 hour at 180 ° C. at a pressure of 40 kg / cm ² to complete the curing of the epoxy prepreg. The molded product was cooled to room temperature, the molded product was peeled, and the peelability was examined. As a result, the releasability after pressing is good,
The appearance was also good.

Comparative Example 1 90 mm having a cast die using the PMP of Example 1
The PMP film was extruded with a φ single screw extruder. Extruder temperature conditions: cylinder temperature 300 ° C, die temperature 280 ° C
Extruded a 50μ T-die film. The extruded film was cooled and solidified with a chill roll at 80 ° C.

Using the T-die film thus formed, press-forming was performed in the same manner as in Example 1, and the releasability and appearance were examined. As a result, the film was broken at the time of peeling, and the releasability was poor. Also, wrinkles were observed on the peeled epoxy surface.

Comparative Example 2 Using the PMP T-die film molded in Comparative Example 1, press molding was performed in the same configuration as in Example 2, and the releasability was examined. As a result, the PMP film could not completely peel into the roughened surface of the blackened copper foil.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an apparatus for manufacturing a release film of the present invention, FIG. 2 to FIG. 4 are cross-sectional views showing a manufacturing process of a multilayer printed wiring board, and FIG. 5 and FIG. It is sectional drawing which shows a layer structure. 1 ... extruder, 2 ... cooling roll, 3 ... heating roll,
4,4 '... drawing roll, 5 ... cutter, 11,11' ... press plate, 12,12 '... cushion material, 13,13' ... press hot plate, 14,14 '... copper foil , 15,15 '…… prepreg, 15 ″
…… Adhesive prepreg, 16,16 ′ …… Release film, 17,
17 '... Inner circuit board.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05K 1/03

Claims (2)

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