JPS6052943B2 - printed wiring board - Google Patents

Description

Detailed Description of the Invention The present invention has excellent thermal properties such as heat distortion temperature and soldering heat resistance, mechanical properties, and adhesive strength between metal foil and insulating base material, and can be easily and inexpensively manufactured. The present invention relates to a printed wiring board that can be used in various ways.

So-called printed wiring boards, which are constructed by laminating a conductor made of metal foil such as copper foil on an insulating substrate, are used in large quantities in fields such as various home appliances, computers, communications equipment, and various instruments. ing.

BACKGROUND ART Conventionally, as insulating substrates for printed wiring boards, composite sheets have been used in which thermosetting resins such as epoxy resins, phenolic resins, and unsaturated polyester resins are combined with substrates such as paper and glass fiber synthetic fibers. All of these are made by coating and impregnating a base material such as paper, glass fiber, or synthetic fiber with a solution usually called varnish, which is made by dissolving a thermosetting resin in a solvent, and then leading the solution to a dryer and heating it. The solvent in the varnish is evaporated and removed, and the polymerization reaction of the resin is advanced to produce a prepreg in the so-called B state,
It has been manufactured by a method in which a predetermined number of prepregs are piled up and heated and pressurized to harden the resin. However, with this method, it is necessary to remove the solvent from the varnish applied to the base material, which not only requires a great deal of expense for recovering and processing the solvent, but also causes the solvent to scatter into the atmosphere, significantly worsening the working environment. Moreover, it takes a lot of time to harden the resin, making it uneconomical. Therefore, the present inventors conducted intensive studies with the aim of improving the above-mentioned drawbacks of the manufacturing process and easily and inexpensively manufacturing printed wiring boards with even better thermal and mechanical properties. By using a plate-shaped molded product made of a resin composite composition as an insulating base material, process problems caused by the use of solvents and curing of resin can be solved, and in addition, printed wiring boards using conventional thermosetting resins can be solved. The present invention was achieved by discovering that a printed wiring board having characteristics equal to or superior to that of the present invention can be obtained.

That is, the present invention uses polyphenylene sulfide resin (
Hereinafter, it will be abbreviated as PPS. ) 85-2% heel weight and length is 5Wr! The present invention provides a printed wiring board using, as an insulating base material, a plate-shaped molded product made of a composite of 15 to 8% of glass fibers with a resin matrix having a crystallinity of 40% or more. The insulating base material of the present invention is PP
In addition to retaining the excellent electrical and chemical properties inherent to S, it has been given even more remarkable thermal and mechanical properties,
It can be applied to ordinary soldering work without any problems and brings great economic benefits to the electrical industry.

The PPS used in the present invention has a structural formula /゛(5/1\\], ,,.,)7, with 9 repeating units represented by S+.
It is a polymer containing 0 mol% or more, preferably 95 mol% or more. If the repeating unit (phenylene sulfide unit of loose bond) is less than 90 mol%, the crystallinity of the polymer is insufficient, and the rigidity, heat distortion temperature, etc. This is not preferable because it causes a decrease in

In addition, PPS can be composed of less than 10 mol % of repeating units having, for example, the following structural formula. These PPSs have a melt viscosity of 50 to 50,000 poise, preferably 100 to 500 poise, measured at a temperature of 300°C and an apparent shear velocity of 200/Sec.
It is appropriate that it be within the range of 0 poise. Melt viscosity is 5
If it is less than 0 poise, sufficient mechanical strength and impact resistance will not be developed, and if it is more than 50,000 poise, glass fiber and PP
When PPS is combined with S, the impregnation of PPS into the gaps between the glass fibers becomes insufficient and desired mechanical strength cannot be expected, so it is not suitable. Note that ordinary additives such as antioxidants, heat stabilizers, lubricants, crystal nucleating agents, ultraviolet absorbers, colorants, fillers, and mold release agents can be added to the PPS used in the present invention. It is also possible to blend small proportions of other types of polymers within a range that does not impede the purpose of the invention.

The length of the glass fiber used in the present invention is 577 mm.
! F7! As long as it is above, it may be used in any state such as chopped fiber, chopped fiber mat, continuous filament mat, woven fabric, knitted fabric, or a combination of two or more of these. A fabric-like material can be particularly preferably used.

In the present invention, in order to obtain a printed wiring board with good heat resistance, mechanical strength and adhesive strength, the length and content of glass fibers contained in the insulating base material and the PPS
The degree of crystallinity is extremely important.

It is necessary to blend the glass fibers with a length of 3 wun or more in an amount of 15 to 8% by weight, preferably 20 to 75% by weight.
If the length of the glass fiber is less than 5T0t or the amount added is less than 15% by weight, sufficient mechanical properties cannot be obtained, and if the amount added is more than 8% by weight, the mechanical properties are deteriorated, which is not preferable. The degree of crystallinity of the insulating base material K (7) PPS matrix is at least 40%, more preferably 50%.
% or more, and if the crystallinity is less than 40%, it is not preferable because deformation during heating will be large and heat resistance will be insufficient.

The degree of crystallinity in the present invention is determined by an X-ray diffraction method (Masao Kakuto, "Polymer X-ray Diffraction", p. 262-2), and specifically, 20=100. and 42
For the diffraction intensity curves in the above range, 20=144, 24
This value is obtained by connecting the diffraction intensities of the range with a straight line to form a baseline, connecting the tails of the diffraction intensity curves with a smooth curve, and dividing the diffraction by the crystal and the amorphous halo. At this time, since the amorphous scattering intensity based on the glass fibers in the sample is significantly smaller than the scattering intensity of amorphous PPS, the diffraction from the glass fibers imparted to the amorphous halo is ignored and no special correction is performed. Nakatsuta. There are no particular restrictions on the method for obtaining a plate-like molded product by combining glass fibers and PPS, but chopped fibers with a length of 3wn or more, mats made of chopped fibers, continuous long fiber mats, woven fabrics, etc. A common method is to alternately stack glass fibers in the form of powder, pellets, sheets, etc., heat them above the melting point of the PPS, pressurize them, and cool them.

According to this method, compared to conventional methods that use varnishes such as epoxy resins and phenolic resins, a good insulating base material can be obtained by simply melting PPS, impregnating it into glass fibers, and then cooling it under pressure. Not only does it eliminate steps such as collection and treatment, it also eliminates the need to harden the resin, making it extremely efficient. Particularly efficient and excellent is a method in which a stack of the above-mentioned glass fiber mat and PPS sheet is fed between a pair of endless metal belts, and then heated, impregnated, and cooled continuously.

The heating temperature in this method is usually 290 to 330°C,
The pressure is 10 to 150 k9/Crll, and the cooling temperature is suitably in the range of about 120 DEG C. or higher and below the melting point (about 285 DEG C.), preferably 140 DEG to 240 DEG C., at which PPS can be crystallized to a degree of crystallinity of 40% or more. It is also possible to use an extruder or the like to melt and knead glass chopped fibers and PPS, pelletize them, and then mold them into a plate by injection molding. Because the glass fibers are cut to 37n1n or less by the shearing force, not only will sufficient mechanical strength not be developed, but the flow during molding will cause the properties of the molded product to become anisotropic, causing warpage in the molded product. This is not desirable because it occurs.

There is no particular restriction on the thickness of the plate-shaped molded product used as the insulating base material in the present invention, and a range of 0.1 to 5.0 wn is usually selected.

In some cases, in order to increase the thickness of the plate-shaped molded product, a sheet made of another resin may be further laminated on one side of the plate-shaped molded product for practical use. The plate-shaped molded product obtained as described above has a load of 18.6 as specified in ASTM D648.
The heat distortion temperature at k9/d is extremely high at 260-285°C, and it not only has extremely excellent heat resistance and solder resistance, but also has extremely excellent mechanical strength, so it has desirable characteristics as a printed wiring board. demonstrate.

There are no particular limitations on the method for manufacturing the printed wiring board of the present invention using the plate-shaped molded product as an insulating base material. For example, after bonding a metal foil such as copper foil to an insulating base material, the metal foil is A so-called subtractive method in which pattern etching is performed, an additive method in which copper or the like is plated in a pattern on an insulating base material, a stamping foil method in which copper foil etc. punched out in a pattern are bonded to an insulating base material, etc. can be used.

Note that the insulating base material and the metal foil such as copper foil can be bonded together without using an adhesive by directly overlapping the metal foils during pressure molding of the base material or after molding, or by using an adhesive. can also be used, but the adhesive strength between the metal foil and the insulating base material is also extremely excellent.

The printed wiring board of the present invention manufactured by such a simplified process has excellent thermal and mechanical properties and good solderability, so it is highly expected to be applied to the electrical industry field. .

The present invention will be explained in more detail with reference to Examples below. Example 1 Sodium sulfide 32.6k9 (25
0 mol, containing 40 wt% of crystal water), 100 y of sodium hydroxide, 36.1 kg (250 mol) of sodium benzoate, and 79.2 k9 of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) were gradually added while stirring. The distillate was heated to 205℃ and contained 6.9k9 of water.
' was removed.

1,4-dichlorobenzene 37.5k9 to the residual mixture
(255 mol), and NMP2O. Add Ok9, 2
Heated at 65°C for 4 hours. The reaction product was washed 8 times with hot water and dried for 24 Tf at 80°C using a vacuum dryer to obtain 2 l of powdered highly polymerized PPS with a melt viscosity of 2900 poise.
．． I got lk9. Using the above PPS, the thickness is 0.7Tn by extrusion molding! n sheets were created.

Next, add these two sheets and a glass continuous fiber mat (Asahi Fiberglass M96OO, basis weight 600k9/d).
) are stacked alternately and supplied between flat molds in a heating press set at 330°C, heated for 3 minutes under a pressure of 5k9/d, and then placed in a cooling press set at 150°C. The mold was transferred, a pressure of 35 k9/d was applied, and the mold was cooled for 5 minutes to obtain a PPS plate-shaped molded product A reinforced with continuous glass fibers having a thickness of 1.6 Tm. Also, the length of PPS powder obtained by the same method as above is 3a7m15T1r! n and 1
5w0n glass chopped fibers (CSO3MA4ll, CSO5MA4ll and CSl5MA4ll made by Asahi Fiberglass) were fed into a Henschel mixer so that the blended amount of glass fiber was 4% by weight, and mixed with PPS powder. A mixture with a flocculent appearance consisting of glass chopped fibers was obtained.

Next, this mixture was supplied between heating presses, pressed and cooled under the same conditions as above to compression mold plate-shaped molded products B, C, and D having a thickness of 1.6 wn. On the other hand, an adhesive consisting of 7 parts of a polyester amide resin consisting of 4 parts by weight of butylene terephthalate units, 2 parts by weight of butylene terephthalate units and 3 parts by weight of dodecane amide units and 3 parts of a bisphenol type epoxy resin (in a monochloroben/methanol mixed solvent). The dissolved solution was coated on a commercially available electrolytic copper foil for printed wiring (thickness: 35 μm) and dried to produce an adhesive-coated copper foil.

Next, the above-mentioned plate-shaped body and copper foil with adhesive are overlapped, and 13
A copper-clad laminate (printed wiring board) was produced by heat-pressing at 0° C. and then heat-curing the adhesive. Table 1 shows the results of measuring various characteristic items of the obtained copper-clad laminate based on JISC648l. Furthermore, for comparison, the length of the above PPS powder is 3W! The pellets obtained by adding 4% by weight of glass chopped fibers and uniformly mixing them in an extruder were put into an injection molding machine and molded to a thickness of 1.6 m1 at a mold temperature of 120°C.
A plate-shaped molded product E with dimensions of 16-12h was created.

A copper-clad laminate was prepared using this plate-shaped molded product E in the same manner as described above, and the results of evaluating various properties are also shown in Table 1.
Note that all evaluation results other than solder heat resistance and peel strength in Table 1 are values for the substrate from which the copper foil was removed by etching.

In addition, the length of the glass fiber in Table 1 is the value determined by observing the ash content under a microscope and with the naked eye after incinerating the plate-shaped molded product.
This result shows that glass fibers are contained in the molded products while maintaining their length in the plate-shaped molded products A, C, and D, whereas in the plate-shaped molded product E that has undergone extrusion and injection molding, the glass fibers are contained in the molded products. It can be seen that the length is cut to 0.3wn or less.

From the results in Table 1, it can be seen that when the length of glass fibers is in the order of 3 or less (No. 1, 2), there are disadvantages such as not only poor soldering heat resistance but also extremely poor bending strength. On the other hand, it is clear that the printed wiring boards (Nos. 3 to 5) of the present invention have improved these drawbacks.

Example 2 1 to 3 extrusion-molded sheets of PPS prepared in the same manner as in Example 1, 1 to 4 sheets of continuous glass fiber mat, and 1 sheet of copper foil, with the copper foil forming the outermost layer, and Copper foil is PPS
The glass fibers were stacked so that they were in direct contact with each other so that the glass fiber content was in the proportions shown in Table 2, and this was supplied between flat molds at room temperature, and the mold was introduced into a heating press set at 330 ° C. After applying a pressure of 10K9/C7i and holding it for 1 hour,
Transfer the mold to a cooling brace set at 150℃ and heat it to 100k9.
By applying a pressure of /d and cooling the powder, the thickness is 1.2
~1.5? Copper-clad laminate (printed wiring board) with good appearance
I got it.

Each laminate was evaluated in the same manner as in Example 1, and the results shown in Table 2 were obtained. From the results in Table 2, it is clear that when the glass fiber content is 15% by weight or less (No. 6), the heat resistance and bending strength are significantly inferior.

Example 3 The PPS powder obtained in Example 1 was extruded to a thickness of 1.
A sheet of 0 Tnm was produced.

Same as Example 2, except that these two sheets and the two continuous glass fiber mats used in Example 1 were stacked alternately, and the cooling breath temperature was varied from water cooling (approximately 20°C) to 180°C. Copper-clad laminates (printed wiring boards) with a thickness of 2.0 WrIn were prepared by performing the following operations and varying the degree of crystallinity as shown in Table 3.
I got it. Each laminate was evaluated for heat resistance, bending strength, etc., and the results shown in Table 3 were obtained. Table 3 shows that the degree of crystallinity is less than 40% (
It is clear that the heat resistance of NOlO,ll) is significantly inferior. Example 4 PPS powder with an apparent melt viscosity of about 150 poise (manufactured by Phillips Petroleum, 64 Litezo V-1)
) to glass continuous long fiber mat (M made by Asahi Fiberglass)
96OO, area weight 600y/d), and then coated with copper foil (thickness 35
μ) are stacked, supplied between endless metal belts, and heated and cooled continuously under pressure to achieve a thickness of 2.5 μm. A copper-clad laminate using the glass fiber-reinforced PPS of i as an insulating base material was obtained.

The molding conditions are heating zone set temperature: 325°C, cooling zone set temperature: 120°C, belt speed: 0.33 m/min, maximum temperature at the center of the product: 298°C, temperature when taking out the product: 1
The temperature was 80°C. The resulting copper-clad laminate (printed wiring board) had a glass fiber content of 37% in the insulating base material, a crystallinity of 57%, a heat distortion temperature of 280°C, and a bending strength of 21 kg/
Mm2, and had excellent heat resistance and mechanical properties.

Furthermore, as a result of evaluating various properties of the copper-clad laminate based on JISC648l, it was found that the copper-clad laminate had excellent properties as shown in Table 4. Example 5 The same PPS powder as in Example 4 was evenly spread on glass cloth (H252, manufactured by Asahi Fiberglass), two sheets were stacked on top of each other, and the sheets were placed between flat molds in a heating press set at 330°C. After applying a pressure of 5k9/Clt and heating for 3 minutes, the mold was transferred to a cooling breath set at 150°C, and a pressure of 35k9/Clt was applied and cooled for 5 minutes to form a mold with a thickness of 0. 65Tn! A plate-shaped molded product reinforced with glass cloth of n was obtained.

Electrolytic copper foil for printed wiring with a thickness of 35 microns was layered on one side of the plate obtained by the above method, and it was supplied between the flat molds in a heating press set at 310'C.
After applying a pressure of .

When various properties of this copper-clad laminate were evaluated, excellent results were obtained as shown in Table 5.

Claims (1)

[Claims] 1 Polyphenylene sulfide resin 85-20% by weight
and 15-80% by weight of glass fibers with a length of 5 mm or more
The crystallinity of the resin matrix is 40%.
A printed wiring board using the plate-shaped molded product as described above as an insulating base material.