JPS61193844A - Double-side metal lined plate for flexible high-frequency circuit - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Technical No. J] The present invention relates to space satellite broadcast receiving antenna circuit boards, microstrip ultra-high frequency circuit boards, space satellite broadcast receiver converter circuit boards, personal radio circuit boards, and other high frequency application equipment. This invention relates to a double-sided metal clad plate for flexible high frequency circuits used as circuit boards and the like.

[Background technology] With the development of the electronics and electrical industries, metal-clad boards for high-frequency circuits used as this type of high-frequency printed circuit boards have become more flexible due to the ease of wiring between parts and the ease of three-dimensional wiring. Metal cladding is being used. Conventionally, the base materials used for flexible metal clad boards include polyimide film, polyethylene terephthalate film, and glass base materials impregnated with epoxy resin, but these materials are il! It had a fatal defect as a metal-clad plate for high-frequency circuits because of its large electrical loss.

On the other hand, polyolefins generally have low dielectric loss and excellent electrical properties in high frequency bands, and are therefore very popular as base materials for metal clad plates for high frequency circuits. However, since polyolefin is non-polar, it has very poor adhesion to metal foil, and when metal foil is etched to form a circuit, it may peel off from the polyolefin base material, or when soldering There are problems such as cracking and peeling, and it has been difficult to maintain performance that can be put to practical use as a metal clad board for circuits.

``Object of the Invention'' The present invention has been made in view of the above points, and uses polyolefin as a base material to have excellent electrical properties in the high frequency band, as well as excellent adhesion to metal foil. The object of the present invention is to provide a double-sided metal clad plate for flexible high frequency circuits that can be formed at low cost.

[Disclosure of the Invention] The double-sided metal clad plate for flexible high frequency circuits according to the present invention is made by laminating and bonding metal foils 2, 2 on the front and back surfaces of a layer 1 of modified polyolefin modified with unsaturated aliphatic carboxylic acids. The present invention will be described in detail below.

In the present invention, polyolefin, which has low dielectric loss and is suitable for the dielectric layer, is used as the resin base material for forming the dielectric layer, but since this polyolefin is nonpolar, it has extremely good adhesion to metal foil. bad. Therefore, in the present invention, a modified polyolefin is used. Polyolefins for modification include high density polyethylene, medium density polyethylene, low density polyethylene,
Monoolefin polymers such as linear low density polyethylene, polypropylene, polybutene-1,4-methylpentene polymer, olefin copolymers such as ethylene-propylene copolymer, ethylene-propylene block fubolymer, ethylene butene copolymer, and these Examples include mixtures. Modified polyolefins are obtained by modifying the polyolefins listed above with unsaturated fatty acid carboxylic acids or their anhydrides. Examples of unsaturated fatty acid carboxylic acids and their anhydrides include maleic acid, itaconic acid, citraconic acid, acrylic acid, maleic anhydride, itafonic anhydride, and citraconic anhydride, and among these, maleic anhydride is most preferred. It is preferable to use maleic anhydride-modified polyethylene.The degree of modification is preferably set so that the content based on unsaturated aliphatic carboxylic acids and their anhydrides is about 0.001 to 3% by weight. It is necessary that the amount is 0.001% by weight based on the surface. As an example of modifying a polyolefin with maleic anhydride, a modified polyolefin can be obtained by melt-kneading a mixture of maleic anhydride, polyolefin, and organic peroxide using an extruder. In addition, instead of the organic peroxide, an inorganic metal compound selected from metal oxides and sulfates of groups Ila, l[a, and b of the periodic table is used in an amount of 0.1 to 10% to meet the melting point of the polyolefin. It can be obtained by reacting at a temperature of This modified polyolefin has 10 to 5
In particular, it is preferable to use the film as a film having a thickness of about 50 to 500 μm in the production of double-sided metal clad plates for flexible high frequency circuits from the viewpoint of flexible performance.

In addition, the metal foil has a thickness of 5 to 60μ, preferably 1
Copper, aluminum, nickel, iron, with a thickness of 0 to 50μ
Also, foils of these alloys, printed thin films of metal pastes, and other electrically conductive foils can be used.

Then, metal M2,2 was layered on both the front and back sides of the modified polyolefin film, and this was applied at a rate of about 2 to 20 kg/am.
By heating and pressurizing for about 1 to 3 minutes at a temperature of about 110 to 170°C, metal foils 2 and 2 are welded and laminated on both the front and back sides of the modified polyolefin layer 1, which serves as a base material, as shown in Figure tA1. A double-sided metal clad plate for circuits can be obtained. Further, as shown in FIG. 2, while extruding the modified polyolefin film 4 from the extruder 8!3, the metal foil 2, which is fed out from the coil 6.6,
It is also possible to produce a double-sided metal clad plate for flexible high-frequency circuits similar to that shown in FIG. 1 by fusing 2 and cooling the laminate with a cooling roll 8 while taking it off with a take-up roll 7.

In this way, continuous production becomes possible. The thus obtained double-sided metal clad board for flexible commercial frequency circuits is used as a flexible circuit board for high frequencies by forming a printed circuit on the metal foil 2 by etching or the like in accordance with a conventional method. At this time, if a circuit is formed on only one of the pair of metal foils 2, 2, the other metal foil 2 can be used as a ground electrode.
If a circuit is formed on each of the two, it can also be used as a flexible double-sided circuit board. Since this material can be bent freely, it is possible to conduct three-dimensional wiring in a bent state.

In the double-sided metal-clad plate for flexible high-frequency circuits obtained as described above, since the polyolefin layer 1 with low dielectric loss constitutes the base material that becomes the dielectric layer, the dielectric It is possible to create a circuit board with low loss and excellent electrical characteristics in the frequency band, and since it is made of polyolefin, the material cost can be manufactured at low cost, making it suitable for consumer applications. This makes it possible to expand the

Since this polyolefin has been modified to have polarity, it will adhere well to the metal M2 and the foil 2, and the circuit formed by etching the metal M2 will not peel off or when soldering. 7. There is no fear of cracks or peeling.

Next, the present invention will be specifically explained with reference to Examples.

A 100μ thick ethylene-maleic anhydride copolymer film 71/A (?rein@anhydride content 0.05% by weight) was used as the modified polyolefin film, and a 20μ thick film was used on both the front and back surfaces of this modified polyolefin film.
layered with copper foil and heated at a temperature of 140℃ and a pressure of 3Kg/c-
A double-sided metal clad plate for a flexible high-frequency circuit was produced by holding under the conditions of 2 for 1 minute to integrate and further cooling.

The results of measuring various properties of the double-sided metal clad plate for high frequency circuits thus obtained are shown in the following table.

In the table below, rD-48/20J is
8. As shown in the previous table, the copper foil of the present invention has excellent adhesion strength, extremely low dielectric constant and dielectric loss values (one order of magnitude higher than conventional products), and improved high frequency characteristics. It was confirmed that Regarding the peel strength, even when immersed in organic solvents such as methanol, tricumylethylene, and 7 setone, the low peel strength shown in the previous table was not observed, and the solvent resistance was also excellent.

[Effect of the invention 1 As described above, in the present invention, metal foil is laminated and bonded on the front and back surfaces of a layer of modified polyolefin modified with unsaturated aliphatic carboxylic acids, so that a polyolefin with low dielectric loss can be obtained. The layers make it possible to obtain a double-sided metal clad plate for flexible high-frequency circuits with excellent high-frequency properties, and since it is made of polyolefin, it can be manufactured at low material cost, and the polyolefin layer has no polarity. It has been modified to have such a property that it can be bonded well to the metal foil, and there is no risk that the circuit formed by the metal foil will peel off.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a schematic diagram showing an example of the manufacturing method of the same. 1 is a layer of modified polyolefin, and 2 is a metal foil.

Claims (3)

[Claims] (1) A double-sided metal clad plate for flexible high-frequency circuits, characterized in that it is made by laminating and adhering metal foils on the front and back surfaces of a layer of modified polyolefin modified with unsaturated aliphatic carboxylic acids. (2) The double-sided metal clad plate for a flexible high frequency circuit according to claim 1, wherein the metal foil is a copper foil having a thickness of 10 to 50 μm. (3) The double-sided metal clad plate for a flexible high frequency circuit according to claim 1 or 2, wherein the layer of modified polyolefin is a layer of maleic anhydride-modified polyethylene having a thickness of 10 to 500 μm.