JPH04155883A - Laminated circuit board - Google Patents

Abstract

PURPOSE:To realize a laminated circuit board which is thin, flexible, and excellent in heat resistance, dimensional stability to moisture, and high frequency stability by a method wherein an unstretched sheet whose main component is polyphenylene sulfide and a biaxially orientated polyphenylene sulfide film are used as insulating material. CONSTITUTION:A biaxially orientated polyphenylene sulfide film layer (A layer), an unstretched polyphenylene sulfide sheet (B layer), and an electric circuit (C layer) are laminated without interposing adhesive agent between them to constitute a laminated circuit board. The unstretched polyphenylene sulfide sheet (B layer) denotes a sheet or a film or a board which is formed through such a manner that PPS composition is formed by fusion into a film or a sheet, or a board 700mum or below in thickness and substantially not orientated. The biaxially orientated polyphenylene sulfide film (A layer) is formed through such a manner that resin composition which contains 90% or more by weight of poly-p-phenylene sulfide is formed by fusion into a sheet, and the sheet is biaxially orientated and thermally treated into a film.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a laminated circuit board.

More specifically, the invention relates to a laminated circuit board in which the insulating material is composed of an unstretched sheet containing polyphenylene sulfide as a main component and a biaxially oriented polyphenylene sulfide film.

[Prior Art] Multilayered laminated circuit boards are increasingly being used in the electrical and electronic industries. In recent years, in particular, from the viewpoint of downsizing and increasing the functionality of equipment, in addition to various properties such as heat resistance, flame retardance, and chemical resistance, thinner products, flexibility, dimensional stability against moisture absorption, stability against high frequencies, and lower costs have been developed. There is a growing demand for a laminated circuit board that has these features.

Conventional laminated circuit boards include (1) laminated circuit boards based on materials such as glass fiber sheets impregnated with epoxy resin, (2) laminated ceramic circuit boards, and laminated circuit boards made of film materials. As an insulating material, a laminated circuit board based on (3) polyimide film or (4) polyester film is known. Furthermore, polyphenylene sulfide film (hereinafter sometimes abbreviated as PPS film) is known as a highly functional film that combines the above-mentioned properties, and biaxially oriented polyphenylene sulfide film (hereinafter referred to as PPS film)
A printed circuit board using P5-BO (sometimes abbreviated as P5-BO) as an insulating material is published in Japanese Patent Publication No. 55-36945, etc., and an unstretched polyphenylene sulfide sheet (hereinafter referred to as PP5-NO
A printed circuit board using insulating material (sometimes abbreviated as ) has been proposed in Japanese Patent Publication No. 7579/1983.

[Problems to be Solved by the Invention] However, the above laminated circuit board has the following problems.

The laminated circuit board described in item (1) lacks flexibility and has a thick base material, so that when multiple layers are laminated, the thickness of the laminated circuit board becomes thick. Such a problem is that when there are limits to the area and thickness of a laminated circuit board, the number of laminated layers decreases, making it impossible to create a high-density laminated circuit board.

The laminated circuit board in item (2) also has the same problems as in item (1), and is expensive.

Although the laminated circuit board using the polyimide film described in item (3) can overcome the above problems, it has poor moisture absorption dimensional stability and stability against high frequencies.

The laminated circuit board using the polyester film described in item (4) has poor heat resistance (soldering heat resistance) and flame retardancy.

From the above points, it is necessary to use a film base material from the viewpoint of flexibility and thinning of the laminated circuit board (the laminated thickness can be reduced and multi-layered), and we selected a film base material that has a well-balanced combination of the above-mentioned characteristics. Must.

PPS film is most suitable as the film base material, but
Those based on PPS and -BO have a high shrinkage rate at high temperatures, and those based on P P 5-NO rapidly decrease in strength when exposed to temperatures near the melting point.
There was a problem in that shape retention deteriorated and processing at high temperatures such as soldering was difficult.

The present invention solves these problems, has heat resistance (thermal dimensional stability, shape retention at high temperatures), flame retardance, moisture absorption dimensional stability, stability against high frequencies, etc., and has thin walls and flexibility. It is an object of the present invention to provide a laminated circuit board having the following characteristics.

[Means for Solving the Problems] The present invention provides a biaxially oriented polyphenylene sulfide film layer (layer A), an unstretched polyphenylene sulfide sheet layer (layer B), and an electric circuit (layer 0) without using an adhesive. This is a laminated circuit board formed by laminating layers.

In the present invention, poly-roof unilene sulfide (hereinafter sometimes abbreviated as PPS) refers to a structure in which 70 mol% or more (preferably 85 mol% or more) of repeating units have a structural formula (D-8+). A polymer consisting of units.If the content of such components is less than 70 mol%, the crystallinity, thermal transition temperature, etc. of the polymer will be low, resulting in poor heat resistance and dimensional stability, which are characteristics of a film made of a resin composition containing PPS as the main component. , impair mechanical properties, etc.

Less than 30 mol% of repeating units, preferably 15 mol%
If the amount is less than 1, there is no problem even if a unit containing a copolymerizable sulfide bond is included.

Further, the method of copolymerization of the polymer does not matter whether it is random or block type.

In the present invention, a resin composition containing poly-p-phenylene sulfide as a main component (hereinafter sometimes abbreviated as PPS-based composition) refers to a composition containing 60% by weight or more of poly-p-phenylene sulfide. .

If the content of PPS is less than 60% by weight, the mechanical properties, heat resistance, etc. of the unstretched sheet made of the composition will be impaired.

The remaining less than 40% by weight of the composition can include additives such as polymers other than PPS, inorganic or organic fillers, lubricants, colorants, and the like.

The melt viscosity of the resin composition was determined at a temperature of 300°C and a shear rate of 2.
00 se-, a range of 700 to 20,000 poise is preferred from the viewpoint of sheet formability.

Unstretched sheet (PPS-N) constituting layer B in the present invention
o) is a general term for films, sheets, and plates with a thickness of 700 μm or less formed by melt-molding the above PPS composition,
Substantially non-oriented.

The biaxially oriented poly-p-phenylene sulfide film (PPS-80) constituting layer A in the present invention is poly-p-phenylene sulfide film (PPS-80).
Roof is a film made by melt-molding a resin composition containing 90% by weight or more of unilene sulfide into a sheet, biaxially stretching it, and heat-treating it. PPS content is 90% by weight
If it is less than 100%, the crystallinity, thermal transition temperature, etc. of the composition will be low, and the heat resistance, which is the feature of the film made of the composition, will be lowered.
Impairs dimensional stability, mechanical properties, etc.

The remaining less than 10% by weight of the composition can include additives such as polymers other than PPS, inorganic or organic fillers, lubricants, colorants, UV absorbers, and the like.

The melt viscosity of the resin composition was determined at a temperature of 300°C and a shear rate of 2.
A range of 500 to 12,000 poise (more preferably 700 to 10,000 poise) at 00 sec' is preferable from the viewpoint of film formability.

The melt viscosity of the resin composition is equal to the melt viscosity of the biaxially oriented PPS film finally obtained.

The thickness of the film is preferably in the range of 10 to 300 μm.

The electric circuit of the present invention is an electrical path wired in various patterns using conductors, and the conductors are usually made of metal such as copper or aluminum, or conductive paint containing copper, silver, carbon, or the like. The thickness of the conductor part is 0.1 to 50 μm
This range is preferable from the viewpoint of subsequent processability. Moreover, electric and electronic components may be mounted on the electric circuit.

The laminated circuit board of the present invention has the above PP5-BO (A layer)
, PP5-No (layer B), and an electric circuit (layer C), and are bonded together without using an adhesive. Here, the adhesive is used for the purpose of bonding each of the above layers, and is used for the purpose of bonding the above three layers.
The thickness is as follows. When the adhesive is included,
The thermal decomposition, moisture absorption properties, etc. of the adhesive adversely affect the laminated circuit board, making it impossible to take advantage of the excellent properties of PPS, and making it impossible to achieve the object of the present invention.

On the other hand, PP5-BO and PP5-N of the present invention.

In order to bond the layers without using adhesive, corona discharge treatment,
Surface treatment such as plasma treatment and primer treatment is 1μm
There is no problem if the thickness is less than 100%.

Further, the number of laminated layers in each layer of the laminated circuit board is not particularly limited, and the C layer does not necessarily have to be laminated on at least one surface of the A layer and the B layer. Further, the thickness of each layer of the laminated circuit board does not necessarily have to be the same. Furthermore, the shape of the laminated circuit board is not limited, and the area of each layer does not need to be the same. For example, one or more layers of the laminated circuit board may protrude from the outside of the laminated circuit board.

Here, an example of the laminated structure of the laminated circuit board of the present invention will be given. For example, considering a 7-layer laminated circuit board, C/A/C/
B/C/A/CXB/C/A/B/C/B/A, C/A
/B/A/C/B/A, C/A/C/B/C/B/C,
Examples include A/C/B/C/B/C/A.

Further, the total thickness ratio (A, /B,) of each of the A layer and B layer of the laminated circuit board is 0. 3-3. The range of 0(7) is preferable in terms of dimensional stability at high temperatures, strength retention at high temperatures, and shape retention.

Further, the total thickness of the laminated circuit board of the present invention is 20 to 200 mm.
A range of 0 μm is preferable in terms of workability and flexibility.

[Manufacturing Method] Next, a method for manufacturing the laminated circuit board of the present invention will be described.

PPS used in the present invention is obtained by reacting an alkali sulfide and paradihalobenzene in a polar solvent at high temperature and high pressure. In particular, sodium sulfide and balajichlorobenzene are
- The reaction is preferably carried out in an amide high boiling polar solvent such as methylpyrrolidone.

In this case, in order to adjust the degree of polymerization, it is most preferable to add a so-called polymerization auxiliary agent such as an alkali or an alkali metal salt of carboxylic acid, and to carry out the reaction at 230 to 280°C.

The pressure within the polymerization system and the polymerization time are appropriately determined depending on the type and amount of the auxiliary agent used, the desired degree of polymerization, etc. The resulting powdered or granular polymer is washed with water and/or a solvent to separate the created salt, polymerization aid, unreacted monomer, etc.

To form this polymer into an unstretched sheet, it is supplied to a melt extruder such as an extruder, heated to a temperature higher than the melting point of the polymer, melted, and continuously extruded through a slit-shaped die to form the film. A non-oriented sheet can be obtained by rapid cooling to a temperature below the glass transition point.

Further, to obtain a biaxially oriented PPS film, the above-mentioned sheet is biaxially stretched and heat treated by a well-known method.

Stretching is 3.0 to 90 to 110°C in both longitudinal and width directions.
Do this in a 4.5x range. Heat treatment is carried out in the range of 180 ° C to melting point, with constant length or limited shrinkage of 15% or less, from 1 to 6
Do this for 0 seconds. Additionally, the film may be relaxed in one or two directions to improve its thermal dimensional stability.

Furthermore, the surfaces of PP5-BO and PP5-NO used in the present invention may be subjected to surface treatments such as corona discharge treatment, plasma treatment, and primer treatment to a thickness of less than 1 μm.

Next, PP5-BOlPPS-No and an electric circuit are laminated. Prior to lamination, electrical circuits are formed in PP5-BO and PP5-No. The method is to use the above film,
A metal layer such as copper or aluminum is laminated on the sheet by a method such as thermocompression bonding, or by a vacuum evaporation method, a plating method, etc., and a desired circuit pattern is etched with an aqueous ferric chloride solution. Alternatively, a method may be used in which a desired circuit pattern is formed using a paint containing a conductor such as copper, silver, or carbon by a method such as screen printing.

The PP5-BO and PP5-No circuit boards thus obtained are laminated by heat fusion to produce a laminated circuit board.

The lamination method is performed using a roll press, a hot plate press, or the like. In the roll press method, for example, several layers of PPS film circuit boards are stacked one on top of the other and laminated by pressing pressure between heating rolls, or one layer at a time or several layers at a time are laminated by a similar method. Also, in the hot plate press, the sheets are laminated in the same manner as above using the press pressure between the upper and lower hot plates. The lamination conditions at this time are:
Temperature 180-270℃, press pressure 1-20kg/cd
These conditions are preferable in terms of adhesiveness and flatness of the laminated circuit board. Furthermore, lamination can also be performed using methods such as impulse or ultrasonic waves. Alternatively, the metal foil can be formed into a circuit by the etching process described above and then laminated together with PP1BO and PP5-No under the above conditions.

[Effects of the Invention] Since the laminated circuit board of the present invention has the above-described structure, it has excellent properties such as heat resistance, flame retardance, chemical resistance, moisture absorption dimensional stability, and stability against high frequencies. It also has flexibility, can be made thinner (in other words, can be made into multiple layers with the same thickness), and also has minimal dimensional change at high temperatures, which was a problem with PPS films, resulting in a laminated circuit board that does not deform.

[Applications] The laminated circuit board of the present invention can be used not only as a circuit board for ordinary electrical and electronic equipment, but also as a high-density circuit board and an irregularly shaped multilayer circuit board since it can be drawn and formed.

Furthermore, at least one side of the laminated circuit board of the present invention may be bonded to another film, a heat-resistant fiber sheet, or a metal plate, or may be coated with another resin and remolded.

[Measurement method, evaluation method] Next, a method for evaluating characteristics and evaluation criteria used in describing the present invention will be described.

(1) Cut the heat shrinkage rate laminated circuit board into a piece 100 mm wide x 130 mm long, mark two places in the longitudinal direction, with a distance of 100 mm between them, and then use a microscope to accurately measure the length of the two marks ( αM). The sample was then heated at a temperature of 250°C for 10
After aging in a hot air oven for a minute, the above lengths are again measured microscopically (β mm). Next, calculate the thermal shrinkage rate using the following formula.

Heat shrinkage rate (%) - world x 100 α (2) Heat resistance at high temperatures 6.
The deformation of the laminated circuit board after it had sagged for 0 seconds was observed based on the following criteria.

○: No deformation at all.

Δ: Partial deformation such as waving is observed in the laminated circuit board.

×: Severe wavy-like deformation occurs on the entire surface.

(3) Flexibility The laminated circuit board was cut out to a size of 10 mm wide and 100 mm long, and the flexibility was measured when bent by hand in the longitudinal direction.

○: Can be easily bent.

△: Is it possible to bend it? It requires a lot of force.

×: It is almost impossible to bend.

(4) Moisture absorption rate After drying the laminated circuit board, 96% at 75%RH and 23℃
It was aged for an hour and measured gravimetrically.

(5) Dielectric properties (dielectric loss) Changes in dielectric properties were investigated by changing the frequency (JIS-C
-6481).

[Example] Next, the present invention will be explained in detail by giving examples.

Example 1 (1) Preparation of PPS unstretched sheet used in the present invention In an autoclave, 32.6 kg of sodium sulfide (250 mol, containing 40 wt% of crystal water) and 100 mol of sodium hydroxide were placed in an autoclave.
g, sodium benzoate 36°1 kg (250 mol),
and 79.2 kg of N-methyl-2-pyrrolidone (sometimes abbreviated as NMP hereinafter) and dehydrated at 205°C.
mole), and NMP20. Add Okg and heat at 265℃ for 4 hours.
Allowed time to react. The reaction product was washed with water and dried to obtain 21.1 kg (yield: 78%) of poly-p-phenylene sulfide containing 100 mol % of p-phenylene sulfide units and having a melt viscosity of 3100 poise.

This composition has an average particle size of 0. 7μm silica fine powder 0. 1w1%, calcium stearate O0Q5wt
% and extruded by a 40m+n diameter extruder.
It was melted at 10°C, filtered through a filter with a 95% cut pore size of 10 μm using metal fibers, and then extruded through a T-die with linear lips 400 mm long and 0.05 mm apart, and the surface was kept at 25°C. An unstretched sheet having a thickness of 25 μm was obtained by casting on a metal drum.

Further, both surfaces of the sheet were subjected to corona discharge treatment at 5000 J/rd (referred to as PPS-No-1).

(2) Adjustment of PPS-BO PP5-BO with a thickness of 25 μm, “Torelina” type 3000 made by ■, was used, and both sides of the film were further subjected to corona discharge treatment at 5000 J/rd (PPS-BO -1).

(3) Creation of electric circuit board PP5-No-1 (B layer) created in (1) and (2)
and PP5-BO-1 (layer A) by patterning an ultraviolet curing type copper paste on one side of each using a screen printing method, irradiating it with ultraviolet rays and curing it to form an electric circuit (layer 0), Two types of circuit boards were created.

(4) Creation of laminated circuit board PP5-BO-1 circuit board (C/A
) and PP5-No-1 circuit boards (C/B) were alternately stacked on top of each other so that the circuit surface and non-circuit surface were stacked, and were laminated by a hot plate pressing method. The laminated structure is 6 layers of C/A/C/B repeating units, and 2 layers with C/A layered on the last B layer.
6 layers (the laminated structure is (C/A/C/B) 6 C/
(Displayed as A). The lamination conditions are 10K at a temperature of 250℃.
for 10 minutes at a pressure of g/a[r.

Apart from this, the laminated structure can be changed to C/B/
C/B/C/A/C/B/C/B/C/A/C/A/C
A laminated circuit board with a total of 26 layers of /A/C/B/C/A/C/A/C/B/C/B was created (laminated configuration ((C
/B)2 C/A) 2((C/A)2 C/B) 2
C/B).

Example 2 Circuit board (C/A) of PP5-BO-1 of Example 1 and P
P5-NC)-1(B) alternately (C/A/B...
... B/C/A) A laminated circuit board with a total number of laminated layers of 20 layers was created (lamination configuration (C/A/B) 6 C/A).

Apart from this, the circuit board (C/B) of PP5-NO-1 of Example 1 and PP5-BO-1 (A) were connected to A/C/B.
/C/B/A/C/B/C/B/A/C/B/A/C/
A laminated circuit board with a total of 20 layers of B/A/C/B/A was created (laminated configuration (A (C/B)2) 2 (
A/C/B), A) Comparative Example 1 A glass epoxy board with a thickness of 100 μm and copper-clad on one side was prepared, and the copper sword of the board was etched with an aqueous ferric chloride solution to form an electric circuit ( C/E). Next, a laminated circuit board having a total of 6 layers was obtained by laminating the circuit surface and the non-circuit surface of the circuit board using an adhesive. The laminated configuration is C
/E/C/E/C/E (laminated configuration (C/E) 3).

The adhesive used for the above lamination is “Chemit Epoxy” TE.
-5920 (manufactured by Toshi), and the thickness of the adhesive layer is 15 μm. Lamination was carried out by a hot plate press method under conditions of a temperature of 120° C. and a pressure of 2 kg/cnf.

Further, the adhesive was cured at a temperature of 150° C. for 1 hour.

Comparative Example 2 Polyimide film with a thickness of 25 μm “Kapton” 100
H (manufactured by DuPont) was prepared as a P layer), and an electric circuit was formed on one side of the film by the method of Example 1 (C/
P). Further, under the conditions of Comparative Example 1, circuit boards were laminated via an adhesive. The laminated structure is C/P...C
/P, the total number of layers was 22 (laminated structure (C/P) +
+).

Comparative Example 3 The circuit board (C/
A) was used to form a laminated circuit board with a total of 22 layers using an adhesive under the conditions of Comparative Example 2 (lamination configuration (C/A) II).

Comparative Example 4 PP, 5-BO-1 circuit board (C/
A) was heat-sealed so that the circuit surface and the non-circuit surface were laminated to obtain a laminated circuit board having a total number of laminated layers of 26 layers (lamination configuration (C/A) 13). The lamination conditions were a hot plate press method at a temperature of 260° C. and a pressure of 10 kg/d.

Comparative Example 5 The circuit board of PP5-No-1 used in Example 1 (Cl3
), a laminated circuit board having a total of 26 layers (laminated configuration (Cl3): 13) was obtained under the conditions of Example 1 so that the circuit surface and the non-circuit surface were laminated.

[Evaluation] The evaluation results of the laminated circuit boards of Examples 1 and 2 and Comparative Examples 1 to 5 are shown in Table 1.

First, the laminated circuit board of the present invention of Example 1.2 and Comparative Example 4
(PPS-BO only), Comparative Example 5 (PPS-N
Let's compare it with the laminated circuit board (only available at O). PP
The laminated circuit board of Comparative Example 4 made only of 5-BO has excellent flexibility, moisture absorption characteristics, dielectric properties, etc., but has a large dimensional change rate at high temperatures. In addition, PP5-N of Comparative Example 5
Materials made only from O will soften and rapidly deform when exposed to high temperatures. On the other hand, the laminated circuit board of the present invention solves the above-mentioned problems and has a high level of balance in heat resistance, dimensional stability at high temperatures, moisture absorption properties, dielectric properties, etc. In addition, since a film is used, the thickness of the laminated circuit board can be reduced (multilayers can be formed if the thickness is the same), and it is highly flexible, thus fully achieving the object of the present invention.

The glass epoxy substrate of Comparative Example 1 was inferior in moisture absorption dimensional stability (moisture absorption rate) and dielectric properties, and also lacked flexibility. Furthermore, since the thickness of the substrate cannot be reduced, the thickness of the laminated circuit board cannot be reduced.

Moreover, the one using the polyimide film of Comparative Example 2 has excellent flexibility and dimensional stability at high temperatures, but has problems with moisture absorption properties and dielectric properties.

In addition, in Comparative Example 3, the laminated circuit board was made of PP5-BO or with an adhesive, so in addition to the problems of Comparative Example 4, the adhesive deteriorated the hygroscopic properties and dielectric properties of PPS. I end up.

Example 3 In the same manner as in Example 1, the thickness was 12 μm, 125 μm, and 38 μm.
μm, 50 μm PP5-BO (A layer) and 25 μm13
8μm, 100μm N 125μm PP5-No
(B layer) was prepared. Furthermore, on one side of each of the above films,
Copper was provided by the plating method (copper thickness: 1 μm). Subsequently, eight types of circuit boards on which copper circuit patterns (layer 0) were formed were obtained by etching with a ferric chloride aqueous solution. Each of the above circuit boards has a laminated structure of C/A/C/B/C/A/C/B/C/A ((C/A/C/B) 2 C/A), and the thickness structure is Six different types of laminated circuit boards were obtained (samples 1 to 6). The lamination conditions were those of Example 1.

[evaluation] The evaluation results of Example 3 are shown in Table 2.

Total thickness (AT) of PP5-BO of the laminated circuit board of the present invention
and the ratio of the total thickness (B1) of PP5-No (A, /Ba)
When the value is less than 0.3, shape retention at high temperatures deteriorates (P
It approaches the characteristics of a laminated circuit board made only of PS-NO (
The characteristics tend to approach those of the laminated circuit board of PPS-BO only.

Claims (1)

[Claims] (1) Biaxially oriented polyphenylene sulfide film layer (
A layer), unstretched polyphenylene sulfide sheet layer (B
A laminated circuit board in which a layer C) and an electric circuit (layer C) are laminated without using an adhesive.