JPS62283694A - Manufacture of printed wiring board - 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] & Detailed Description of the Invention "Object of the Invention" The present invention relates to a method for manufacturing a printed wiring board, which has a low dielectric constant and electrical characteristics that can be adjusted as appropriate to suit each purpose of use. The present invention aims to provide a method that can easily and appropriately manufacture a variety of controlled printed wiring boards using the same material.

Industrial Application Fields: Manufacturing technology for various types of printed wiring boards that can be used in a variety of devices, from general electronic devices to computers that require faster signal speeds.

2. Description of the Related Art Printed wiring boards conventionally used in electronic devices and the like are as follows.

■ Glass epoxy base material or paper epoxy base material, which is made by impregnating glass cloth or paper with epoxy resin and hardening it, or paper phenol base material, which is made by impregnating paper with phenol resin and hardening it.

■ Flexible insulating base materials such as polyimide film and polyester film.

■ Heat-resistant printed wiring base material made from a composite base material of plus fiber and neliimide.

■ Low conductivity base materials such as Nitemoshi Keppler, -Liimide Keppler, and epoxy quartz.

■ Low dielectric constant base material made of glass cloth and tetrafluoroethylene resin.

Problems to be Solved by the Invention However, in the conventional products as described above, the characteristics of the product obtained are specified in any case, and it is not possible to obtain products with diverse characteristics from the same material. Also, ■■ is a conventional and common type, but it has a high dielectric constant, and it is difficult to use it in modern computers that require high speed. can't get it. Incidentally, the dielectric constants of these materials are approximately as follows with respect to the frequency IMHz.

■ 4.5 to 5.5 ■ 3.5 to 5.0 ■ 4.3 to 47 Although ■ has excellent heat resistance, its dielectric constant is 3.5.
~4.0, which does not immediately meet the purpose of increasing signal speed as described above.

(2) has a low dielectric constant of 2.5 to 3 and is considered a low dielectric constant base material, but it tends to have problems with adhesiveness to metal foil and has difficulties in processability.

In addition, these materials differ in terms of dielectric constant, which simply does not meet the requirements of computers, etc., and also in characteristics such as heat resistance, heat conductivity, mechanical strength, and flexibility. In order to respond quickly to the application, it is necessary to consider these characteristics and decide on the material to be actually used. Therefore, in order to promptly respond to such demands, it is necessary for manufacturers to constantly arrange and stock a variety of materials, otherwise they will only be able to manufacture made-to-order products for certain specific products.

Of course, even if a variety of materials are prepared, the material selected for new custom production cannot necessarily be preferred due to the above-mentioned characteristics.

"Structure of the Invention" Means for solving the problem A polytetrafluoroethylene porous structure is used as a material,
The porous i-structure of the material is impregnated with a resin liquid that meets the required characteristics of the intended wiring board, such as heat resistance and low dielectric constant, and then is cured under pressure under pressure conditions that match the required characteristics of the wiring board. A manufacturing method for printed wiring boards that is characterized by:

The working polytetrafluoroethylene porous 'JR structure itself exhibits a low dielectric constant of about 1.1 to 1.8. In addition, although polytetrafluoroethylene itself is chemically stable and is not suitable for bonding with other resins or adhesives, such porous structures can be impregnated with an appropriate resin liquid and bonded. let

The characteristics of the resulting printed wiring substrate are primarily changed depending on the electrical and physical or chemical characteristics of the resin liquid impregnated and bonded as described above.

As described above, when the porous structure impregnated with the resin liquid is pressure-cured, the properties of the resulting printed wiring substrate can be changed to a second degree by appropriately selecting the rolling conditions.

By combining the above-mentioned primary and secondary characteristic changes, the electrical, physical, and chemical characteristics of printed wiring boards obtained by using the same material can be varied in various ways.

EXAMPLES Further details of the invention as described above; ia
To explain this, the characteristics required of today's printed wiring boards used in electrical equipment and other devices are truly diverse. For example, in the above-mentioned computers, there is a strong demand for higher signal speeds, and today ultra-high-speed elements such as gallium arsenide have been developed to speed up signals, and printed wiring to which these elements are applied. There is also a strong desire for substrates to have characteristics that can quickly respond to higher speeds. On the other hand, substrates on which IC chips are directly mounted are required not only to have a low dielectric constant, but also to have a high thermal expansion coefficient, thermal conductivity, and mechanical strength, depending on the mounting form.

However, in the case of the above-mentioned computer, the signal propagation delay time is proportional to the square root of the dielectric constant of the material, and in the case of a strip line, it is expressed by the following equation.

7E□ (n formula/ml, where t: dielectric constant of the material, C: speed of light 3 x 10' m/see) Therefore, in order to respond quickly to higher signal speeds, it is essential to reduce the dielectric constant 1 of the material.

On the other hand, in the case of a board on which an IC chip is directly mounted as described above, it is important to properly match the thermal expansion coefficient, thermal conductivity, and mechanical strength of the board even if the dielectric constant C is sacrificed to some extent. becomes.

The present invention was created after repeated studies in order to promptly meet the various demands regarding printed wiring boards as described above, and in terms of dielectric constant, the polytetrafluoroethylene porous structure 1 itself has However, this polytetrafluoroethylene has a low dielectric constant of 1.2 with a porosity of 80.However, this polytetrafluoroethylene has a drawback in mechanical strength against tensile and compressive forces. By forming this into a porous structure, other resin components can be impregnated and hardened, and these disadvantages can be overcome by the resin component impregnated in this way. It also increases the mechanical strength of the porous tissue against tensile and compressive forces.

However, as mentioned above, when the material is simply impregnated with a low-permittivity or heat-resistant resin, a considerable number of pores still remain in the structure, and the etching solution may penetrate into the pores during etching to form a circuit. This results in unnecessary etching, unavoidable residual adhesion of etching solution components, and furthermore, when used as a printed wiring board, outside air, especially moisture, enters into the holes and deteriorates the insulation and dielectric properties. adversely affect.

Such disadvantages are overcome by adding press forming in the present invention, but on the other hand, when the porosity is reduced by this press forming, the dielectric constant gradually increases.

Therefore, when molding a product impregnated with a resin by pressure curing as described above, the dielectric constant of the product obtained even if the same resin is impregnated can be changed by varying the degree of pressure t. Various properties such as insulation, flexibility, mechanical strength and other properties can be obtained.

The above-mentioned polytetrafluoroethylene porous structure 1 is formed by rolling and stretching a polytetrafluoroethylene film to form numerous fine fibers 12 in a spider web shape between micro nodules 11 as shown in FIGS. 1 and 2. It can be obtained as something. Such a structure 1 can be used by appropriately polymerizing a plurality of sheets, and the porosity thereof is generally 3.
It can be prepared as 0-90%. The higher the porosity, the lower the dielectric constant, and in the case of the above porosity range, it is 1.1 to 1.8.

The resin solution impregnated into the polytetrafluoroethylene porous structure 1f as described above includes heat-resistant resins, low dielectric constant resins, etc., and specific examples of these resins are as follows.

Heat-resistant resins: Epoxy, polyimide, polyester, acrylic, triazone, bismaleimide, triazine resins Low dielectric constant resins: Polyolefins, polysulfones, polyethersulfones, FEPs, etc. The porous material impregnated with such resins Press molding hardening for the structure 1 is appropriately selected depending on the characteristics of the intended wiring board, and if the purpose is a low dielectric constant, a light press molding is performed.
In addition, if insulation is important, sufficient press molding is performed. If it is hardened by applying pressure with a press machine or a roll, the porous structure will be crushed appropriately, and the porosity of the substrate material made of the impregnated resin and the structure 1 will be reduced, and depending on the degree, the electrical and Mechanical properties are determined and dimensional stability is also ensured.

For the base material obtained as above, stC and 5j04
Thermal conductivity, dimensional stability, mechanical strength, etc. can be further improved by mixing inorganic substances such as quartz and powder into the polytetra 7A/oleoethylene resin. Dimensional stability and strength can also be improved by laminating fibrous reinforcing materials such as glass fibers, clay fibers, aramid fibers, etc., or by laminating or mixing short fibrous reinforcing materials.

Furthermore, a reinforcing material made of a resin film such as polyimide film, polyetherketone film, polysal 7-on film, or polyester film is laminated on at least one side or inside of the above-mentioned base material to improve mechanical strength such as edge tear strength and tensile strength. It further improves physical properties and prevents moisture absorption and air permeability into the tissue.

Furthermore, by providing a hard insulating material such as a glass epoxy board or a ceramic filter plate on at least one surface or inside of the base material, bending strength and dimensional stability are increased, and a product excellent as a component mounting board can be obtained.

Furthermore, by providing a heat conductive material such as a soft or hard metal body, heat generated when the circuit is energized can be effectively conducted, and especially in the case of a soft heat conductor, it is possible to obtain a flexible board that can change the shape of the board. .

When forming a conductive circuit using metal foil such as steel foil on the above-mentioned base material, there are cases where the resin impregnated into the base material has poor adhesion to the metal foil, or when fibrous or resin film reinforcement is used. When the metal foil is laminated on a material or a hard insulator, it can be bonded using an adhesive, and the conductive circuit can also be formed by an ion derating method, a vacuum evaporation method, sputtering, or the like. Of course, it is also possible to provide a plating catalyst layer and form a conductive circuit by the adating method.In the present invention, the substrate material as described above has a certain porosity and a coating layer as described above is applied on the front and back sides. When formed, coating the peripheral side with resin liquid to form an airtight layer blocks outside air from entering the tissue, and also prevents etching solution from entering.
Enables etching of minute circuits and 9 turns, and improves insulation and resistance against moisture intrusion. Avoid deterioration of quality.

A specific manufacturing example of the product according to the present invention will be described below.

Production Example 16 A porous material with a thickness of 0.1 m and a porosity of 70, 41J tetrafluoroethylene and 40% epoxy att+.
The dielectric constant of the base material, which is laminated and bonded to the front and back sides of a base material impregnated with vt% and press-molded and cured to a thickness of 0.08 wm+, is 2.2, which is much lower than the conventional one! We were able to obtain a product suitable for use in high-speed computers.

Production Example 2 50wt% of quartz howder of 8 degrees 4 to 8 μm was added to the same porous tetrafluoroethylene membrane 1 as in molding example 1.
Mixed thickness 0. l ■ Porous polytetrafluoroethylene membrane 100wt1i? 30w xy resin
The dielectric constant of steel foil laminated under pressure on both sides of a base material which is impregnated with t part and hardened by press molding to a thickness of 0.09 mm is 25, which is a desirable characteristic for high-speed computers with good heat conduction. It was confirmed that it has.

Production Example 1 A 4-liter trifluoroethylene membrane with a porosity of 70% was impregnated with epoxy resin T in the same manner as in Production Example 1, and as shown in FIG. The dielectric constant of a product on which copper foil 4 was laminated and cured by applying pressure at a reduction rate of 20% was 2.5, and was a product with excellent dimensional stability suitable for use in high-speed computers.

Production Example 4゜In place of the quartz f1 fiber 3, a polyester ether ketone film 5 was inserted as shown in Fig. 4, and the rolling reduction was 3.
The dielectric constant of the printed circuit board obtained in the same manner as in Production Example 3, except for the setting of 3%, was λ8, and as in Production Example 3, it was found that it was a product suitable for use in high-speed computers with excellent mechanical strength. Ta.

Manufacturing Example & A polytetrafluoroethylene porous film with a porosity of 70% is impregnated with 40 wt% of epoxy resin, and a glass epoxy plate 6 with a thickness of 0.1 mm and a copper foil 4 are bonded on both sides as shown in FIG. It has a dielectric constant of 3.1 when laminated and cured by rolling down at a rolling reduction rate of 20%, and has excellent mechanical strength and bending rigidity, making it a preferred printed circuit board for high-speed computers that mount a large number of parts. ``Effects of the Invention'' According to the present invention as explained above, printed circuit boards with various characteristics can be appropriately manufactured using the same material, polytetrafluoroethylene porous body, and
This invention facilitates the material management for obtaining this type of substrate and can be quickly applied to a variety of uses, making it a highly effective invention industrially.

[Brief explanation of the drawing]

The drawings show the technical content of the present invention, and FIGS. 1 and 2 are micrographs showing a representative example of a fiber-based polytetrafluoroethylene porous structure used in the present invention, and FIG. 6 to 6 are explanatory diagrams showing enlarged cross-sectional structures according to manufacturing examples of the present invention. In these drawings, 1 is polytetrafluoroethylene porous group A 11H1iE, 3U quartz Ra,
4 is copper foil, 5 is polyester ether ketone film,
6 is a glass epoxy plate, 11 is a micro nodule, and 12 is a fine fiber. . Patent applicant: Soyanogi Gore-Tex Co., Ltd. Inventor: Hatakeyama
Real opening piece 1)
Department Moriya Hiroten J Koku No. 6 ■ N No. 6 En No. / En I'r (l:fJ group division f(=

Claims (1)

[Claims] 1. A polytetrafluoroethylene porous structure is used as a material, and the porous structure of the material is impregnated with a resin liquid that meets the required characteristics of the intended wiring board, such as heat resistance and low dielectric constant. 1. A method for manufacturing a printed wiring board, comprising: drying the printed wiring board, and then hardening under pressure under rolling conditions that correspond to the required characteristics of the wiring board. 2. The method of manufacturing a printed wiring board according to claim 1, which is made of a polytetrafluoroethylene porous structure mixed with inorganic powder. 3. The method for manufacturing a printed wiring board according to claim 1 or 2, wherein the pressure curing is performed by press or roll pressure. 4. The method for manufacturing a printed wiring board according to any one of claims 1 to 3, which comprises forming a coating layer of inorganic powder on a pressure-cured base material surface. 5. Fibrous reinforcing materials such as glass fiber, quartz fiber, and aramid fiber, resin films such as polyimide film, polyether ether ketone film, polyether sulfone film, and polyester film, and hard insulation are applied to the pressure-cured base material surface. body, either a soft or hard metal body
The method for manufacturing a printed wiring board according to any one of claims 1 to 4, which comprises layering one or more types. 6. In the base material to be cured under pressure, fibrous reinforcing materials such as glass fiber, quartz fiber, aramid fiber, etc., resin films such as polyimide film, polyether ether ketone film, polyether sulfone film, polyester film, and hard insulation. body, either a soft or hard metal body
The method for manufacturing a printed wiring board according to any one of claims 1 to 4, which comprises layering one or more types.