JPH0444384A - Manufacture method of high frequency substrate - Google Patents

Abstract

PURPOSE:To lower epsilonr or tan delta and enhance resistance to high temperature and nonflammability by laminating metal foil or metal sheet on both sides or one side of a dielectric sheet which comprises a specified weight of polyphenylene sulfide film and superpolymeric polyethylene. CONSTITUTION:Metal foil or metal sheets are lamianted on both sides or one side of a dielectric sheet where polyphenylene sulfide films and superpolymeric polyethylene-made porous sheets are laminated so that the polyphenylene sulfide may range from 10 to 90 wt.% while the superpolymetic polyethylene may range from 90 to 10 wt.%. Or similarly, metal foil or metal sheets are laminated on both sides or one side of a dielectric sheet where polyphenylene sulfide powder ranging from 1 to 90 wt.% is mixed with superpolymeric polyethylene powder ranging from 90 to 10 wt.% and the mixture is calcined and molded so that the sheet may be porous. Then, after laminated, both the dielectric sheets are heated and pressure-molded. A PPS films 1 and HMPE porous sheets are further laminated and a bonding layer 4 is also laminated. Then, copper foil is laminated as metal foil 3 on the farthest layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high frequency substrate used in a high frequency region and a method for manufacturing the same.

[Conventional technology]

Recently, the frequency of signals used in the electronics and communication industries has gradually shifted to the high frequency range, and the importance has shifted from the kilohertz range, which has traditionally been widely used, to the megahertz and gigahertz ranges. . In these high frequency ranges, the signal speed and signal loss have a large effect on circuit performance, and the electrical components and laminates used are required to improve signal speed and reduce loss in the high frequency range. The signal speed of the circuit on the laminated board depends on the dielectric constant (hereinafter referred to as ε) of the dielectric, and the lower ε is, the faster the signal speed is. In addition, the signal loss is caused by the dielectric's ε and tan δ (δ:
(dielectric loss angle), and the lower ε1 and tanδ, the lower the loss. For this reason, dielectrics used in high frequency substrates are required to have low ε and tan δ. ε
A glass cloth impregnated with a resin such as polytetrafluoroethylene or polyethylene is used as a dielectric material having a low value of .

Although εr and tan δ are slightly higher than polytetrafluoroethylene or polyethylene, high-frequency substrates using polyphenylene sulfide as a dielectric are also known because of its excellent heat resistance.

Problem to be solved by the invention C] A polytetrafluoroethylene/glass cloth substrate using a dielectric material made by impregnating glass cloth with polytetrafluoroethylene is difficult to manufacture due to the high melting point and low fluidity of polytetrafluoroethylene. However, there was a problem in that molding at high temperatures and for a long time was required, resulting in high costs. On the other hand, a polyethylene/glass cloth substrate in which glass cloth is impregnated with polyethylene has a drawback of poor solder heat resistance and flame retardancy because the melting point of polyethylene is low.

In addition, for substrates made of polyphenylene sulfide (hereinafter sometimes referred to as PPS) as a dielectric, it is common to add about 40% by weight of short glass fibers as a reinforcing agent to eliminate the brittleness of PPS. Since ε1 and tan δ of PPS are high and combined with these, ε and tan δ become even higher than in the case of PPS alone, which has the disadvantage that ε1 and tan δ are too high for use as a high frequency substrate.

An object of the present invention is to provide a high-frequency substrate having low ε and tan δ, excellent heat resistance, and improved flame retardancy, and a method for manufacturing the same.

[Means for Solving the Problems] As a result of intensive study on a high-frequency substrate with low ε7 and tan δ, excellent heat resistance, and improved flame retardancy, and a method for manufacturing the same, the present inventors discovered that polyphenylene sulfide 10
~90% by weight and ultra-high molecular weight polyethylene (hereinafter referred to as HMW)
It has been discovered that the above problem can be solved by laminating metal foil or metal plate on both sides or one side of a dielectric sheet consisting of 90 to 10% by weight (sometimes referred to as PE), and based on this knowledge, the present invention has been developed. I was able to complete it.

That is, the present invention provides polyphenylene sulfide 10 to
The present invention provides a high frequency substrate characterized in that a metal foil or metal plate is laminated on both or one side of a dielectric sheet made of 90% by weight and 90 to 10% by weight of ultra-high molecular weight volutelene.

The high frequency substrate of the present invention includes, for example. A dielectric sheet in which a polyphenylene sulfide film and a porous sheet of ultra-high molecular weight polyethylene are laminated such that polyphenylene sulfide is 10 to 90% by weight and ultra-high molecular weight polyethylene is 90 to 10% by weight, or polyphenylene sulfide powder is 10 to 90% by weight. % by weight and 90 to 10% by weight of ultra-high molecular weight polyethylene powder, sintered and formed into a porous dielectric sheet, laminated with metal foil or a metal plate on both sides or one side, and heated and pressed. It can be manufactured by

The present invention will be explained using the drawings. Figures 1 to 4 show examples of the laminated structure of the high frequency substrate of the present invention.
Figures 1 and 2 show that PPS film 1 (6 sheets in both Figures 1 and 2) and HMWPE porous sheet 2 (1 sheet in Figure 1, 2 sheets in Figure 2) are laminated, and then In this case, an adhesive layer 4 is laminated, and m foil is laminated as the metal foil 3 on the outermost layer.

Figures 3 and 4 show porous sheets (hereinafter referred to as PPS-HM) made by mixing PPS powder and HMWPE powder and sintering and forming the mixture.
(sometimes referred to as WPE sheet) 5 (one sheet in Figure 3, two sheets in Figure 4) and a resin-impregnated reinforcing layer 6 (three sheets in Figure 4) are laminated, and the outermost layer is a metal layer. The foil 3 is made by laminating copper foil. In this way, the dielectric sheet of the present invention can be applied to PPS film, HMWPE sheet, ppS
- A plurality of HMWPE sheets may be laminated with or without an adhesive layer or a resin-impregnated reinforcing layer.

Then, the laminated structure shown in FIGS. 1 to 4 is heated and pressure-molded using a press or the like to produce a high-frequency substrate.

The PPS film used in the present invention is produced by uniaxially or biaxially stretching PPS. For example, a biaxially stretched PPS film commercially available from Toshi Co., Ltd. under the trade name "Torelina j" is preferably used. The thickness of the film may be 10 to 100 μm, and the PPS is 10
The thickness of the film may be combined to give a desired weight ratio in the range of 10 to 90% by weight of HMWPE and 10 to 90% by weight of HMWPE. The thickness of the dielectric sheet is usually 0.5 to 5 mm. Since PPS film has the disadvantage of low surface tension and poor adhesion, it is better to use a film that has been subjected to plasma treatment, corona treatment, etc. to increase its surface tension.

Ultra-high molecular weight polyethylene (H
HMWPE used for porous sheets (MWPE) and HMWPE powder is produced by Ziegler polymerization technology, and its average molecular weight is 1 million to 50,000 as measured by the Kikohiro method.
It has a molecular weight of 0,000,000, which is extremely large compared to the 20,000 to 200,000 of general polyethylene. For example, Mitsui Petrochemical Industries (HIZEX MILLION, MIPERON), Asahi Kasei (Santic), West German Hoechst (HO3TALEN),
, GUR), Percules Inc. (HIFAX, 100
0) etc. are preferably used.

HMWPE porous sheets are made by sintering HMWPE powder particles and bonding the particles together by fusion, with a thickness of 0.5 to 5 m.
It is molded into a sheet. There is a continuous layer of air outside the bonded particles.

A method for producing a porous HMWPE sheet is to deposit HMWPE powder particles onto a base material such as a film or metal heald, and then use rolls or bars to maintain a constant distance between them and the base material. There is a method of continuously forming a porous sheet of HMWPE by passing the HMWPE powder particles through a heating furnace to form them into a constant thickness, and then passing them through a heating furnace to heat and sinter the particles. At this time, the HMWPE powder particles may be coated with an adhesive, or particles having adhesive properties, a stabilizer, a crosslinking agent, a flame retardant, a coloring agent, etc. may be added.

The HMWPE powder used in the present invention preferably has an average particle diameter of 1 to 1 mm.

In order to obtain a smooth HMWPE porous sheet, it is particularly preferable that the average particle diameter is 0.001 to 0.1 mm.

The PPS powder used in the present invention has an average particle size of 0.
．． Preferably, OO is 1 to 1 mm. In order to have a smooth surface of the porous sheet obtained by mixing and sintering PPS powder and HMWPE powder, it is particularly preferable that the average particle diameter of PPS is from o,oot to 0.1 mm.

The PPS powder and the HMWPE powder may be mixed using a Hennel mixer, a blender, etc., and the sintered porous sheet may be formed in the same manner as the HMWPE porous sheet is formed.

The reason why the proportion of PPS is 10 to 90% by weight and the proportion of HMWPE is 90 to 10% by weight is that if PPS is less than 10% by weight, there is almost no flame retardant improvement effect;
This is because if it exceeds % by weight, the PPS itself is brittle, and even if it is heated and pressed to form a substrate, the dielectric will crack or break and the substrate will not be able to exhibit its performance.

Examples of metal foils and metal plates laminated on dielectric sheets include:
Examples include gold, silver, copper, aluminum, nickel, stainless steel, iron, iron alloys, copper alloys, etc. Preferred are W4 foil, aluminum foil, aluminum plate, and iron alloy plate.

Thicknesses of 10 to 508 m are preferably used.

The adhesive layer is for strengthening glabella adhesion in a high frequency substrate such as PPS, HMWPE, metal foil or metal plate, and resin-impregnated reinforcing layer. If the structure of the adhesive layer contains a large number of polar groups, the ε and tan δ of the dielectric may become high. In such cases, it is desirable to minimize the thickness of the adhesive layer.

Adhesives, adhesive films, etc. are used as the adhesive layer, and examples of such adhesives include acrylic resins, polyester resins, polyurethane resins, phenolic resins,
Examples include epoxy resin, chloroprene rubber, nitrile rubber, epoxy phenol, phthyral phenol, nitrile phenol, and the like. In addition, as an adhesive film,
(1) Ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, ethylene-acrylic acid copolymer, ethylene-maleic acid copolymer, ethylene-maleic anhydride grafted copolymer, ethylene-methacrylic Conventional copolymerization of α,β-unsaturated carboxylic acid, its ester, its anhydride, or its metal salt, or saturated organic carboxylic acid to polyolefin, such as glycidyl acid-vinyl acetate terpolymer, ionomer polymer, etc. Alternatively, examples include a copolymer obtained by graft copolymerization, (n) a mixture of a polyolefin and the copolymer of the above (1), and (III) a film of an adhesive compound containing a polyolefin and a tackifier, etc. can. The adhesive layer preferably has a crosslinkable group in its formulation and is crosslinked by ionizing radiation, an organic peroxide, a silane compound, or the like.

As the resin-impregnated reinforcing layer, glass cloth, glass nonwoven fabric, plastic fiber woven fabric, etc., which are usually used for substrates, can be used.
Non-woven fabric or other reinforcing agent impregnated with resin face and dried is used. Examples of resins include resin compositions of polyester resins, epoxy resins, phenol resins, melamine resins, diallyl phthalate resins, polyimide resins, bismaleimide triazine resins, PPO resins, or PPS resins and crosslinkable polymers or crosslinkable monomers. Preferably, polyester resins, epoxy resins, and polyimide resins having relatively low ε and tan δ are used.

The heating and pressing conditions for heating and pressing in the present invention are heating temperature: 150 to 330°C, applied pressure: 10 to 100 kgf/
cm (1.0~9.8MPa), application time 2~10
It is preferable to set it as minutes. In addition, it is preferable to heat and press under uniform conditions by sandwiching between stainless steel mirror plates or the like. At this time, the apparent density of the porous sheet of HMWPE and the porous sheet obtained by mixing PPS and HMWPE is 8% of the true density of HMWPE or the mixture of PPS and HMWPE.
It is desirable to eliminate porosity so that the apparent density of the porous sheet is 80% of the true density.
If it is less than 1, the ε and tan δ of the sheet are preferably low, but air bubbles remain in the sheet, and liquid may seep into the sheet during etching, through-hole plating, etc., which will adversely affect the substrate properties.

[Effect]

In order to improve the heat resistance of polyethylene, which has small ε and tan δ and excellent dielectric properties, a method is basically used to crosslink the polyethylene and reduce the fluidity of the resin.

For the purpose of improving heat resistance, it is sufficient to use HMWPE, which has low resin fluidity, but like polytetrafluoroethylene, HMWPE has a high viscosity when heated and melted, so it is difficult to use ordinary extrusion molding or injection molding. The disadvantage is that it is difficult to adapt.

HMWPE has improved heat resistance due to its low fluidity compared to general polyethylene having a molecular weight of 20,000 to 20,000, but has poor moldability and flame retardancy. In order to improve its moldability, a porous sheet of HMWPE can be heated and pressed to form an HMWPE sheet. At this time, the HMWPE porous sheet was compressed only in the thickness direction, and the particles fused together and the porosity disappeared.
It becomes a sheet of MWPE. This means that the press temperature is 330
°C1 applied pressure 40kgf/ail (3.9MPa)
Even if a porous sheet of HMWPE (approximately 1 m+ in thickness) is press-formed for 10 minutes under the high temperature and high pressure conditions of Kararekaru.

On the other hand, PPS itself has heat resistance and flame retardancy, but ε
1 and tan δ are higher than those of HMWPE, and the resin alone is extremely hard and brittle. Moreover, it is 15°C higher than the melting point3
It is a resin with very low viscosity and high fluidity at around 00°C.

As in the present invention, a PPS film and a porous sheet of HMWPE are laminated, a metal foil or a metal plate is laminated thereon, and the PP is heated and its viscosity is lowered by heating and pressure forming.
As S flows to fill the voids in the HMWPE porous sheet under pressure, the voids in the pores are crushed and PPS and H
A sheet is formed with a mixed layer of MWPE. As a result, HMWPE, which has poor flame retardancy, is combined with PPS, which has excellent flame retardancy and heat resistance, thereby improving flame retardancy and significantly improving heat resistance. The brittleness of PPS is improved by combining it with HMWPE, and the adhesion between PPS and HMWPE is significantly improved due to the anchoring effect of the two resins.

A sheet formed by heating and pressing a dielectric sheet formed by mixing PPS powder and HMWPE powder and sintering the mixture to become porous can obtain the same effect as described above without using a PPS film.

The dielectric ε and tan δ of the obtained substrate are HM W P
The value will be between HMWPE and PPS depending on the mixing ratio of E and PPS. When PPS is used as a dielectric, glass fiber or inorganic filler is added to improve its brittleness, but the dielectric properties of the filler are generally the same as those of PPS alone.
, and tan δ, and as a result, ε is higher than PPS alone.
, and the value of tan δ becomes high. By combining PPS and HMWPE, its ε and tan δ do not need to add fillers to PPS, and HMWPE has a low εr.
, m tan δ can be set to a significantly lower value.

〔Example〕

Example 1 Using the apparatus shown in FIG. 5, a polyester film (SL type, Teijin Ltd.) base material 7 with a thickness of 50 um was placed along a stainless steel belt 8, and coated with a cow-nose coater 9.
MWPE powder 10 (Miperon XM220, average particle size 0
．． 03 Kaku, melting point 136°C1 bulk density 0.4g/c+j,
The true density of polyethylene (O, 94 g/C4, trade name of Mitsui Petrochemical Industries, Ltd.) was formed to a thickness of 0.47 m on the base material No. 7, and heated and sintered in a heating furnace (160°C) No. 11. A porous sheet of HMWPE with an apparent density of 0.5 g/cd was obtained.

Two of these porous sheets were used to obtain the configuration shown in FIG. 2, and six 50 μm thick PPS films, Torelina 3030 (trade name, Toshi Co., Ltd.), were stacked and sandwiched between them. Then, on the outside of the porous sheet, 10M was applied as an adhesive layer.
50 μm attomer NE irradiated with r a d electron beam
A film of O60 (trade name of Mitsui Petrochemical Industries, Ltd., linear low-density polyethylene grafted product) (thermal xylene insoluble content, 70% by weight) was provided, and an electrolytic copper foil with a thickness of 35 μm was applied to one side via this adhesive layer. Laminated, sandwiched between 2mm thick stainless steel mirror plates, and heated at 300°C120 using a press.
kg/cTA (2, OMPa) for 5 minutes under heat and pressure to obtain a high frequency substrate with a dielectric sheet thickness of 0.85 mm.

The composition is 347% by weight of PP and 53% by weight of HMWPE. In the same manner, the dielectric properties (measurement frequency: 12GH2) of high frequency substrates obtained by changing the number of porous sheets and the number of PPS films were measured and are shown in FIG.

We also conducted a combustion test according to the UL94HB standard, and the PPS shown in Figure 7
The combustion rate according to the composition ratio of hMWPE is shown. Since the thickness of the test piece is less than 3.05 mm, the burning rate is 63.5
Compatible with tJL94HB at less than aon/min.

Example 2 PPS powder was Toplef PPS T-1 (trade name of Toblen Co., Ltd., average particle diameter 50 μm, bulk density 0.
27-0.30 g/cd, true density 1.36 g/c
d) Miperon XM-220 was used as HMWPE powder, and these were blended so that PPS and HMWPE were each 50% by weight and mixed using a Henschel mixer. Then, it was sintered using the same equipment as in Figure 5 except that it was sintered directly on a stainless steel belt without using a film base material, and the apparent density was 0.7 g/c + a and the thickness was 1.15.
A sintered sheet of mm was obtained. This sintered sheet has a thickness of 211 mm.
Sandwiched between IIl stainless steel mirror plates with a 0.7 tm thick spacer at 300°C, 20kg/cdl (2,
0 MPa) and was heated and pressed for 5 minutes to obtain a composite sheet of PPS and HMWPE having a thickness of 0.7 mm and a density of 1.15 g/cm. A resin-impregnated reinforcing layer on both sides of this sheet with a thickness of 6
Prepreg impregnated with epoxy resin and copper foil are laminated on 0μm glass cloth at 170°C at 120kg/ctl (
2.0 MPa) for 90 minutes to obtain a high frequency substrate. Similarly, dielectric properties and UL94HB standard combustion tests were conducted on composite sheets obtained by changing the mixing ratio of PPS and HMWPE (without lamination of epoxy prepreg and copper foil), and the results are shown in Figures 6 and 7. .

Comparative Example 1 A porous sheet of HMWPE obtained in the same manner as in Example 1 was sandwiched between 2 m thick stainless steel mirror plates and pressed at 180°.
A HMWPE sheet having a density of 0.93 g/cfll and a thickness of 0.47 mm was obtained by heating and pressing C120 kg/all (2, OMPa) for 5 minutes. Using two of these sheets, six 50 μm thick PPS films were stacked and sandwiched in the same way as in Example 1, and furthermore, Atmer NEO 60 irradiated with electron beam and 35 μm copper foil were provided as an adhesive layer on the outside of the HMWPE sheet, and heated. Pressure was applied to obtain a high frequency substrate with a dielectric thickness of 0.85 mm. Unlike the substrate obtained in Example 1, the obtained substrate could be easily peeled off from the interface between the PPS sheet layer and the HMWPE sheet layer. Copper foil and adhesive layer, adhesive layer and HM
Adhesion to the WPE sheet layer was good.

Comparative Example 2 Using PPS powder (Toprene PPS T-1), it was put into a 0.7 mm thick spacer placed on a 2 mm thick stainless steel head plate, and the stainless steel head plate was placed on top of the 300 mm thick spacer. °C120kg/ctA (2,OMPa
), an attempt was made to produce a PPS sheet with a thickness of 0.7 cm by pressing for 5 minutes. However, when the stainless steel head plate was removed after cooling, the PPS had already broken into small pieces, and a sheet made of PPS alone could not be obtained. Similarly, PPS and HM
No cracking occurred in the composite sheets obtained by setting the composition ratio of WPE to 90% by weight and 10% by weight, respectively.

Table 1 shows a comparison of the high frequency substrates obtained in Example 1.2 and Comparative Example 1.2.

According to the present invention, as shown in FIG.
By setting the composition ratio of E to 10% by weight or more of PPS, the drawback of flame retardancy of HMWPE alone can be improved. Further, as shown in Comparative Example 2, the brittleness of PPS alone can be improved by increasing the amount by weight of HMWPEIO. By using a porous sheet of HMWPE and a PPS film, the difficulty in moldability due to the high viscosity of HMWPE when melted by heating has been improved, and PPS
Independent brittleness and adhesion are improved. The same effect as described above can also be obtained by mixing PPS powder and HMWPE powder, forming a porous sheet by sintering, and then forming the sheet by heating and pressing.

〔Effect of the invention〕

The high frequency substrate of the present invention has low ε and tan δ, and has excellent heat resistance and flame retardancy. Further, the method for manufacturing a high frequency substrate of the present invention has excellent moldability and can easily manufacture the high frequency substrate of the present invention.

[Brief explanation of drawings]

Figures 1 to 4 are cross-sectional views showing examples of the structure of the high-frequency substrate of the present invention, Figure 5 is an explanatory diagram of a continuous porous sheet forming device, and Figure 6 is a diagram showing polyphenylene sulfide (PPS) and ultra-high molecular weight A graph showing the dielectric properties (relative dielectric constant ε7, dielectric loss tangent tan δ) depending on the composition ratio of polyethylene (HMWPE). Figure 7 shows polyphenylene sulfide (PPS).
It is a graph showing the burning rate according to the UL94HB standard depending on the composition ratio of ultra-high molecular weight polyethylene (HMWPE). Explanation of symbols 1 Polyphenylene sulfide (PPS) film 2 Ultra-high molecular weight polyethylene (HMWPE) porous sheet 3 Metal foil 4 Adhesive layer 5 Mixed porous sheet of polyphenylene sulfide (PPS) and ultra-high molecular weight polyethylene (HMWPE) resin-impregnated reinforcing layer 7 Base material Stainless Steel Held Plastic Powder 10 Hand-nose type coater heating furnace... /HMW
PE (WL%) Figure 6 Figure 7

Claims (5)

[Claims] 1. A high frequency substrate comprising a dielectric sheet made of 10 to 90% by weight of polyphenylene sulfide and 90 to 10% by weight of ultra-high molecular weight polyethylene, with metal foil or a metal plate laminated on both or one side of the dielectric sheet. 2. A high frequency substrate comprising a metal foil or a metal plate laminated on both or one side of the dielectric sheet according to claim 1 with an adhesive layer or a resin-impregnated reinforcing layer interposed therebetween. 3. A dielectric sheet is made by laminating a polyphenylene sulfide film and a porous sheet of ultra-high molecular weight polyethylene so that the polyphenylene sulfide content is 10 to 90% by weight and the ultra-high molecular weight polyethylene content is 90 to 10% by weight. Metal foil or A method for manufacturing a high frequency substrate, which is characterized by laminating metal plates and forming them under heat and pressure. 4. Polyphenylene sulfide powder 10-90% by weight
and 90 to 10% by weight of ultra-high molecular weight polyethylene powder, sintered and formed into a porous dielectric sheet, laminated with metal foil or metal plate on both sides or one side, and heated and press-molded. A method for manufacturing a high frequency substrate, characterized by: 5. A method for producing a high-frequency substrate, comprising laminating metal foil or a metal plate on both sides or one side of the dielectric sheet according to claim 3 or 4 via an adhesive layer or a resin-impregnated reinforcing layer, and then heating and press-molding the same. .