JPH0246062Y2 - - Google Patents

Description

[Detailed description of the invention] "Purpose of the invention" The present invention relates to the invention of a printed wiring board, which provides a printed wiring board that has an extremely low dielectric constant and is stable in handling and equipment settings, thereby increasing the speed of equipment. It is something that we try to do.

Industrial applications Printed wiring boards for electronic devices, etc.

Conventional technology Printed wiring boards are widely used in electronic devices as an alternative to complicated conductor connections and arrangements, but such conventional boards are made of epoxy base materials,
Generally, a conductor constituting an electric circuit is formed directly on a glass epoxy base material, a ceramic base material, or the like.

Note that there is also one in which the circuit-forming conductor is directly adhered to the surface of a flexible base material such as polyimide resin or polyester resin.

Problems that the invention aims to solve By the way, in recent years, ultra-high-speed devices such as gallium arsenide ICs have been developed, and increasing the speed of printed wiring boards such as the one mentioned above has become an issue. In order to increase the speed of devices, it is required that the dielectric constant of the base material be small, but in the conventional materials mentioned above, this dielectric constant is quite large at 4 to 7 (at 1 MHz). , it is difficult to respond quickly enough to such requests.

``Constitution of the invention'' Means to solve the problem 70% porosity on the base material surface that has the required mechanical strength
A printed wiring board characterized in that a conductor forming an electric circuit is bonded to a fusion layer of tetrafluoroethylene-hexafluoropyrene copolymer via the porous film of polytetrafluoroethylene resin as described above.

Function By using a porous membrane made of polytetrafluoroethylene resin with a porosity of 70% or more, its dielectric constant is extremely low at 1.1 to 1.3 (at 1MHz).
By adhering the conductor that forms the electric circuit through such a porous film with a low dielectric constant, the signal transmission speed can be sufficiently increased to create a gallium arsenide IC.
In combination with other ultra-high-speed elements, a circuit with a high signal speed is formed.

Achieving the strength and stability of a printed wiring board in a board, and optimizing its handling and settings for electronic equipment.

Adhesion using tetrafluoroethylene-hexafluoropyrene copolymer provides adhesion with favorable chemical resistance, and also achieves stable adhesion without damaging the pore structure of the continuous porous polytetrafluoroethylene resin membrane. The result is a board with little change in circuit characteristics due to changes.

EXAMPLE To explain the specific embodiment of the present invention shown in the attached drawings, as shown in FIGS. 1 and 2, a base material 2 for obtaining the required mechanical strength
A porous membrane 1 of polytetrafluoroethylene resin is adhered to the surface with an adhesive layer 5, and a conductor 3 for forming an electric circuit is adhesively formed on the porous membrane 1, and the base material 2 is made of ceramic. , paper phenol, glass epoxy, paper epoxy, glass cloth polyimide, polyimide, polyester, etc. having the required rigidity and mechanical strength can be used.As the circuit forming conductor 3, materials such as those shown in FIG. Either a copper or other metal foil layer 3a or a vapor deposited or sputtered layer 3b as shown in FIG. 2 may be used. The adhesive layers 4 and 5 are made of tetrafluoroethylene-hexafluoropyrene copolymer (FEP).
By using this method, it is possible to obtain a product in which the structure of the polytetrafluoroethylene resin porous membrane is less likely to be damaged, and the circuit characteristics are less affected by temperature changes. Adhesion using FEP is applicable.
Since FEP does not dissolve with solvents, it can be effectively bonded by heat fusing.

Some examples of the polytetrafluoroethylene porous membrane 1 formed between the base material 2 and the circuit-forming conductor 3 are shown in FIGS. 3 and 4. By processing a fluoroethylene resin film by rolling or stretching or both, a structure is formed in which a large number of micro nodules 11 are connected in a spider web shape by countless microfibers 12. The pores 13 between the fibers 12 are as fine as 0.02 μm, and combined with the water repellency of the resin itself, they are water-impermeable and do not allow liquids such as water to pass through, and are used in subsequent processes. It is sufficiently resistant to etching liquid. The porosity is 70% or more, generally 80% or more, and even reaches 92 to 93%, but due to the fine fiber structure as described above, tetrafluoroethylene- Stable adhesion can be achieved by the adhesive layer 5 formed by fusing hexafluoropyrene copolymer (FEP). Further, the conductor 3b formed by vapor deposition or sputtering can be formed into a thin and solid layer with respect to the non-layer of the porous membrane 1 as described above. Alternatively, by forming a thin layer of adhesive 4 on the surface by laminating or coating with another resin, desirable adhesion of the conductor 3 can be achieved without impairing the basic characteristics of the fibrillated porous membrane 1. The dielectric constant of the fibrillated porous film 1 thus formed on the base material 2 is approximately 1.1 to 1.3 (at1M
Hz), which is significantly smaller than the above-mentioned conventional wiring board base material, and by using the porous film 1 with such a low dielectric constant, the signal transmission speed of the printed wiring board can be increased. By combining the above-mentioned ultra-high-speed elements, etc., it is possible to construct an electric circuit with a high overall signal speed.

"Effects of the invention" According to the invention as explained above, the signal transmission speed is improved by forming a circuit-forming conductor on a base material through a porous membrane of polytetrafluoroethylene resin with a porosity of 70% or more. The present invention provides a printed wiring board that speeds up the processing of circuits, makes it easy and accurate to handle it and set it inside the device, and maintains the polytetrafluoroethylene porous resin structure in a perfect state by bonding with FEP. This is a highly effective idea industrially, as it can improve the characteristics and effectively improve the performance of electrical equipment when combined with recently developed ultra-high-speed elements.

[Brief explanation of the drawing]

The drawings show embodiments of the invention,
Figures 1 and 2 are partial cross-sectional views of the printed wiring board according to the present invention, and Figures 3 and 4 are microscopic photographs showing the fiber shape of the porous polytetrafluoroethylene resin membrane, respectively. . However, in these drawings, 1 is a porous polytetrafluoroethylene resin membrane, 2 is a base material, and 3 is a porous polytetrafluoroethylene resin membrane.
is a conductor forming an electric circuit, 4 and 5 are adhesive layers,
11 is a micronodule, 12 is a fine fiber, and 13 is a pore.

Claims (1)

[Scope of utility model registration request] 70% porosity on the base material surface with the required mechanical strength
A printed wiring board characterized in that a conductor forming an electric circuit is bonded to a fusion layer of tetrafluoroethylene-hexafluoropyrene copolymer via the porous film of polytetrafluoroethylene resin as described above.