JPS61294894A - Making of metal based laminate board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides an 8
The present invention relates to a method for obtaining an I-layer plate.

(Prior art) Metal-based printed wiring boards consist of a metal core plate and a conductive circuit layer provided on the surface of the metal core plate through an insulating layer, and have excellent heat dissipation and magnetic shielding properties, and are useful for hybrid IC boards, etc. It is used for various purposes.

Conventionally, as shown in the cross-sectional view of FIG. 3, the material of this metal-based printed wiring board is a laminate made of epoxy resin-impregnated glass fiber mat (glass Oil separation is made by heat-pressing epoxy 3' to cover the surface of the core plate 1, and at the same time, flowing the epoxy resin in the glass epoxy into the holes 11 to cover the surfaces of the holes 11. Ta.

(Problem to be Solved by the Invention) However, in the 81-layer board in which the core plate is coated with glass epoxy, air bubbles 12 tend to remain on the surface of the holes 11 (, ILl
A serious drawback was that insulation failure occurred when a through hole was drilled in the l. Furthermore, glass epoxy does not have sufficient high-frequency characteristics (and depending on the application, even higher performance is desired.

In order to solve the above problems, the present inventors investigated a method of covering the metal core plate, including the hole surface, with a highly heat-resistant thermoplastic resin. However, it has not yet been perfect in cases where even higher quality is required.

(Means for Solving the Problems) The present invention produces a laminate with extremely few remaining bubbles by hot pressing a heat-resistant thermoplastic resin film and a metal core plate provided with through holes in a reduced pressure atmosphere. It was successfully obtained.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing an example of a laminate obtained by the method of the present invention, and FIG. 2 is a sectional view showing another example.
The one shown in the figure has a metal core plate 1 coated and insulated with a film 2 of heat-resistant thermoplastic resin, and a conductive circuit is provided on the surface of the metal core plate 1. The layers are laminated and a conductive circuit is provided on this layer 3.

The metal core plate used in the present invention has a large number of through holes 11 formed in advance, and has a thickness of usually about 0.1 to 1.6 mm. Materials include iron, aluminum, copper, zinc, etc.

This core plate 1 is subjected to surface roughening treatments such as sandblasting, liquid honing, and etching to achieve a JIs surface roughness.
It is preferable that the surface is finely roughened so that the center line average roughness defined by B 0601 is 1 μm or more and 12 μm or less, particularly 1.2 μm or more. This is thought to be due to the fact that air between the layers easily escapes during hot pressing, and the anchoring effect of the rough surface combines to increase the adhesive strength.

At the same time, it is preferable to perform treatments such as alumite treatment, alodine treatment, and resin coating to improve adhesive strength.

As the heat-resistant thermoplastic resin film 2, a thermoplastic resin having soldering heat resistance, such as a film of polysulfone, polyetheretherketone, polyphenylene sulfide, etc., can be used.
Resins having a D648.18.6k(+/cn+2) of 200°C or higher, such as films of polyetherimide (200°C), polyethersulfon (203°C), polyamideimide (274°C), are preferred. .

The thickness of the film 2 is preferably about 0.25 to Q, about 5 mm, taking into account the thickness reduction during 1alI.

In order to laminate the core plate 1 and the film 2, they are overlapped and heated under reduced pressure. The degree of reduced pressure (difference between normal pressure and residual pressure) is 600n+mHg or more, preferably 650
mm1-I shall be 0 or more. If the degree of pressure reduction is lower than this, bubbles cannot be completely treated.

When heat pressing is performed under normal pressure, air bubbles remain in the pores and between the layers, and not only are these air bubbles not easily removed even when high temperature and pressure are applied, but the film 2 may flow out or undergo thermal deterioration due to the harsh heat and pressure bonding conditions. disadvantages arise. However, when hot pressing is performed under reduced pressure conditions with a degree of reduced pressure of about 600 mm1-1Q, most of the air between the layers and in the pores is easily removed while the film 2 is in a solid state, unlike those containing liquid components such as glass epoxy. Moreover, since pressure is constantly applied to the resin, there are almost no visible bubbles. It also has the great effect of providing high adhesive strength by suppressing oxidation of the entire bottom core plate surface due to heating during pressing.

Here, the heating temperature needs to be in the range above the flow start temperature of the resin constituting the film 2 and below the thermal decomposition temperature, so it naturally varies depending on the material of the film 2, but generally it is less than 200°C. The adhesive force between the core plate 1 and the film 2 is weak, and if the temperature exceeds 450°C, the film 2 will flow and the thickness will decrease significantly, which is not preferable, so the temperature should be in the range of 200 to 450°C. Preferred temperatures are, for example, 350 to 380°C for polyetherimide, 320 to 360'C for polyether rifane, 280 to 340'C for polysulfone, and 300°C for polyamideimide.
~400℃, 350~ for polyetheretherketone
The temperature range is 380°C.

Within these ranges, by selecting an appropriate pressing pressure, the film 2 will not flow out significantly during pressing, and the film 2 will melt and a part of it will flow into the hole 11 and fill it, and the surface of 7L11 will be good results are obtained.

In addition, the press pressure should preferably be in the range of 50 to 200 kQ/cm2; if it is less than 50 kQ/cm2, even under reduced pressure, air bubbles between the layers and in the holes will be sufficiently removed, and the adhesive strength will be weak.
If it exceeds QQ kg/cm2, the thickness of the film 2 will decrease unnecessarily, making it impossible to obtain a laminate with a predetermined thickness. Practically speaking, sufficient adhesive strength can be obtained with a pressure of 100 kg/cm2.

Once the heating press is completed, cooling begins. It is preferable to pressurize during this cooling, but it is not necessarily necessary to maintain reduced pressure.

Figure 2 shows a laminate with a particularly preferred configuration. When obtaining such a laminate, an uncured prepreg such as glass epoxy and, if necessary, a conductive material such as copper foil are added on the ζ film layer 2. Layer the metal foils at around 120~2oO℃ (
Pressing may be performed by applying a pressure of 5 to 150 kg/cm2 at 0 m degrees. In this case, it is not necessary to carry out the process in a reduced pressure atmosphere. If the temperature is lower than 120°C, the adhesive force will be weak;
If the temperature exceeds 00°C, thermal decomposition of the resin in the prepreg tends to occur, which is not preferable. The time is 10 minutes or more so that the resin in the prepreg is sufficiently cured.

Prepreg 3 is a mat made of glass fiber or the like, epoxy resin, phenol resin 1. It is impregnated with thermosetting resin such as polyester resin or allyl resin, and has a thickness of 0.1 to 0.
It is best to use several layers of about 2111 m in length.

When the prepreg layer 3 is provided on the surface of the laminate in this way,
This improves the surface smoothness by compensating for the tendency of thermoplastic films to cause "sink marks," and also improves the heat-resistant dimensional stability, solvent resistance, etc. of the insulating layer.

(Example 1) Diameter 0.5-5. A metal core plate of 2I below, which had a large number of mm-sized through holes, was prepared.

a) Aluminum plate 1.6111m thick (surface roughness 1.2μ
b) Aluminum plate with a thickness of 1.6 mm (surface roughness 0.2μ, with alodine treatment) A polyetherimide film with a thickness of 0.3 mm was placed on both sides of these core plates, and the atmospheric pressure was applied. The material was heated and pressed for 90 minutes at a press pressure of 100 kg/cm2, and then cooled while being pressurized. Then, on both sides of the resin layer,
Two sheets of glass epoxy having a thickness of Q and 1 mm were stacked one on top of the other and pressed for 10 minutes at a temperature of 170° C. and a pressure of 50 kg/cm 2 (under normal pressure atmosphere) to obtain a laminate.

Then, the resin inside the hole was cut to form an opening, and the surface was observed under a microscope to check for the presence of air bubbles. Those with no air bubbles with a diameter of 2 μm or more were rated ○, and those with bubbles were rated X. Furthermore, the adhesive strength between the core plate and the film was measured using JrS C6481. The results are shown in Table 1.

Table 1 NO degree of decompression Core plate Temperature Adhesive force Air bubbles (mml
1g) ('C) (ka/cm)1
600 a 350 1.3 02 60
0 a 370 2.2 03 500
a 370 2. OX4 0 a3
70 1.1 X5 600 b 37
0 0.9 As is clear from the results of 0 or more,
No. 4, which is not depressurized, and No. 3, which is insufficiently depressurized, do not leave enough air bubbles, but no air bubbles remain on the pore surfaces in No. 1 to No. 2 and No. 5, which are made by the method of the present invention and are heat-pressed under reduced pressure. It is also understood that a rough-surfaced plate is preferable as the core plate in order to obtain high adhesive strength.

(Example 2) Aluminum core plate a) whose surface was treated with sulfuric acid alumite (surface roughness 1.3mm) (7) A polyether sulfur A film with a thickness of 0.3mm+ was overlaid on both sides, and 600IllR
Under Hg atmosphere, temperature 330°C, press pressure 100
It was heated and pressed at kg/cm2 for 75 minutes.

Next, glass epoxy was laminated on both sides of the resin layer in the same manner as in Example 1 to obtain a laminate having the structure shown in FIG. 2. The laminate had no air bubbles, sufficient adhesion between the layers, and a smooth surface.

(Effects of the Invention) According to the present invention, a laminate can be obtained that is free of air bubbles not only on the surface of the core plate but also in the pores where bubbles have conventionally remained significantly.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing an example of a laminated plate obtained by the method of the present invention, and FIG. 3 is a cross-sectional view showing a conventional 8!1 layer plate. 1... Metal core plate 11... Through hole 2.
...Heat-resistant thermoplastic resin layer 3...Prepreg 1st
Zui 2 Calm Figure 3

Claims (1)

[Scope of Claims] A heat-resistant thermoplastic resin film and a metal core plate having through holes are heated at a temperature of 200 to 450°C and a pressure of 50 to 300 kg in a reduced pressure atmosphere with a degree of reduced pressure of 600 mmHg or more.
A method for producing a metal-based laminate, which comprises heating and pressing under conditions within a range of /cm^2 to cover the surface of the core plate with the resin and filling the through holes. 2) The method according to claim 1, characterized in that a finely roughened plate having a surface roughness of 1 μm or more is used as the metal core plate.