JPH03166930A - Electric laminated sheet - Google Patents

Abstract

PURPOSE:To obtain an electric laminated sheet having a low dielectric characteristic and excellent in perforating processability for a through-hole by arranging a surface layer composed of a resin material having good adhesiveness to both surfaces of a continuous porous sheetlike base material composed of a resin material having a low dielectric constant and allowing a part of the resin material of the surface layers in the pores of the sheetlike base material. CONSTITUTION:An electric laminated sheet has a dielectric constant of about 2.0 - 3.5 and fluoroplastic is used as a resin for a sheetlike base material in general. This sheetlike base material is a continuous porous material having a large number of continuous pores opened thereto so as to pierce both surfaces thereof and a surface layers 2 are layers only composed of a resin containing no glass cloth and a thermosetting resin such an epoxy resin, a polyimide resin or a PPO rein is used. This electric laminated sheet is obtained by arranging the resin films for the surface layers 2 to both surfaces of the continuous porous sheetlike base material 1 and further arranging metal foils 3 to the outsides thereof and subjecting the whole to pressure molding under heating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an electrical laminate used in the manufacture of printed circuit boards. [Prior Art] As shown in FIG. 2, as an electrical laminate used in the manufacture of printed circuit boards, a sheet-like continuous porous base material 10 made of fluororesin is coated with thermosetting glass cloth on both sides. Metal foil 1 via resin-impregnated prepreg 11.11
2.12 (for example, copper foil) is bonded to a copper foil-clad electrical laminate.

Although fluororesin is a useful material due to its low dielectric constant (especially in high frequency ranges), its adhesion to metal foils and other resins is poor. Therefore, a sheet-shaped delivery porous base material is made in advance from a fluororesin, and then a metal foil is arranged with a Bripreg interposed therebetween, and then heated and pressed to form the shape. The metal foil is strongly adhered to the prepreg impregnated with a highly adhesive resin, and on the other hand, the prepreg is also strongly adhered to the sheet-like base material due to some of the impregnated resin entering the communication holes. This results in strong adhesion between the sheet-like base material and the metal foil (Japanese Patent Application Laid-Open No. 1-159242
Publication No.). [Problems to be Solved by the Invention] However, in the conventional electrical laminate described above, there are problems in that the low dielectric constant property of the fluororesin sheet base material is not fully utilized and the dielectric constant is not very low. The problem was that the through-hole drilling processability was not good, making it difficult to use for double-sided printed circuit boards. In view of the above circumstances, it is an object of the present invention to provide an excellent electrical IIi laminate that makes full use of the low dielectric constant properties of the sheet-like base material and has good punchability for through-holes.

[Means to solve the problem]

In order to solve the above problem, the single-layer laminate according to the present invention is made of a resin material with a low dielectric constant: a surface layer made of a resin material with good adhesiveness is arranged on both sides of a single-piece base material. is,
The sheet-like base material is a continuous polymorphous material, and a part of the resin material G of the surface layer is inserted into the pores thereof. Specifically, as shown in Fig. 1, the structure of a double-sided metal foil-covered laminate is made by laminating metal foils 3.3 on both sides of a sheet-like material 1 with a surface layer 2.2 in between. It has become. There is also a single-sided metal foil laminate structure in which the metal foil is only on one side. There is also a single board structure without metal foil, but in this case it goes without saying that it is necessary to further bond the metal foil to make a printed circuit board. The electrical laminate of the present invention usually has a thickness of Q, 1 to 2.
It has a dielectric constant of about 2.0 to 3.5.

Fluorine-based 4M resins are commonly used as 4M resins for sheet-laying base materials [more specifically, polytetrafluoroethylene (
PTFE), tetrafluoroethylene perfluorovinyl ether copolymer (PPFA), tetrafluoroethylene 67-fluoropropylene copolymer (PFEP), tetrafluoroethylene ethylene copolymer (PETFE), trifluorochloride ethylene resin (PCTFE)], silicone resins, polyphenylene sulfide resins, etc. are also used. The sheet-like base material of the present invention is a continuous porous material having a large number of communicating holes penetrating between both surfaces of the sheet, and usually has a thickness of about 0. 0 1 to 1 tm, pore diameter: 0.3 to 10
μ (more preferably 0.5-In), porosity = 50-
About 95% is used.

The surface layer 2 is a resin-only layer that does not contain glass cloth (it may contain ordinary additives such as a hardening agent), and has a thickness of 0.
01 to 1 fl, and thermosetting resins such as epoxy resin, polyimide resin, and PPO resin are used. The electrical laminate of the present invention has, for example, a surface layer of a resin film (thickness: 0
．． A film of about 0.01 to 1 fl. Usually, heating temperature = about 150-330℃, pressure: 5-50
The laminated plate is formed under the conditions of about kgf/cd and time: about 30 to 120 minutes. In some cases, the metal foil 3 is placed on only one side, or is not placed at all to obtain a laminate. If the latter metal foil 3 is not placed at all, the metal foil 3 is applied later on one or both sides. It goes without saying that the electrical laminate of the present invention is not limited to the materials and numerical ranges exemplified above. [Function] In this invention, the surface layer 2 between the sheet-like base material 1 and the metal foil 3 consists only of resin and does not contain glass cloth with a high dielectric constant as in the conventional case. The low dielectric constant property of the material is fully utilized. With conventional electrical laminates,
Even if the dielectric constant of the sheet-like base material is low, the dielectric constant of the prepreg glass cloth is high, so the dielectric constant as a whole is quite high. On the other hand, in the electrical laminate of the present invention, since there is no glass cloth with a high dielectric constant, the low dielectric constant of the sheet-like base material becomes dominant, and the dielectric constant as a whole becomes low.

Furthermore, if there is a glass cloth, punching holes cannot be performed, and even when drilling holes, the drill hits the fiber intersections of the glass cloth, causing the drill position to run out, resulting in poor hole position accuracy. Since the electrical laminate of the present invention does not include glass cloth, such inconveniences during drilling for through-holes are eliminated.

Of course, the metal foil strongly adheres to the surface layer of the resin, which has good adhesive properties, and the surface layer adheres strongly to the sheet-laying base material due to some of the resin entering the communication holes, resulting in a sheet-like shape. Needless to say, the base material and the metal foil are strongly adhered to each other.

〔Example〕

Next, examples of the electrical laminate of the present invention will be described.

Example 1 As a sheet-like base material, communicating pore diameter: in, porosity: 75%
, Thickness: 0. A 1'n PTFE sheet was used.

An epoxy resin film with a thickness of 50 nm is placed on both sides of this continuous porous PTFE sheet, and an electrolytic copper foil with a thickness of 35 μm is placed on the outside of this film. An electrical laminate was obtained.

Example 2 - As a sheet-like base material, communicating pore diameter: l, w, porosity: 75
%, thickness: 0. A 1 tm PTFE sheet was used. A polyurethane resin film with a thickness of 50 nm is placed on both sides of this continuous porous PTFE sheet, and an electrolytic copper foil with a thickness of 35 nm is placed on the outside of this film, and heated and pressed to shape it. An electrical laminate with copper foil on both sides was obtained.

Example 3 As a sheet-like base material, communicating pore diameter: ip, porosity = 75%
, Thickness: 0. A 1 tm PTFE sheet was used.

This continuous porous P. 50pm thick on both sides of TFE sheet
A PPO (polyphenylene oxide) resin film was placed on each side, and an electrolytic copper foil having a thickness of 35p1 was placed on the outside of each film, and the sheets were molded under heat and pressure to obtain an electrical laminate with both sides covered with copper foil.

Comparative Example 1 - Double-sided copper foil-covered electrical laminate was carried out in the same manner as in Example 1, except that instead of the epoxy resin film, a 50 nm thick prepreg made by impregnating an alkali-free E glass cloth with epoxy resin was used. A board was obtained - Comparative Example 2 - Double-sided copper foil was prepared in the same manner as in Example 2, except that instead of the polyimide resin film, a prepreg with a thickness of 50 nm, which was made by impregnating a non-alkali E glass cloth with polyimide resin, was used. A stretched electrical laminate was obtained.

Comparative Example 3 - A double-sided copper foil-covered electrical laminate was produced in the same manner as in Example 3, except that instead of the PPO resin film, a prepreg with a thickness of 50 nm made of alkali-free E glass cloth impregnated with PPO resin was used. I got it. The dielectric constants of the electrical laminates of Examples 1 to 3 and Comparative Examples 1 to 3 thus obtained were measured. The results are shown in Table 1.

Table 2 Comparing the dielectric constants of the corresponding laminates of Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3, it is found that the electrical laminate of the present invention has a It is clear that the dielectric constant of the sheet material is considerably lower, and that the low dielectric constant characteristics of the sheet-like base material are fully utilized. [Effects of the Invention] As described above, since the surface layer of the electrical laminate of the present invention is made only of resin without glass cloth, the low dielectric constant characteristics of the sheet-like base material can be fully utilized. and, moreover,
It is highly practical with excellent through-hole drilling processability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing the structure of an example of an electrical laminate according to the present invention, and FIG. 2 is a sectional view schematically showing the structure of a conventional electrical laminate.

Claims (1)

[Claims] 1 A surface layer made of a resin material with good adhesiveness is arranged on both sides of a sheet-like base material made of a resin material with a low dielectric constant, and the sheet-like base material is a continuous porous material, and the surface layer is formed in the pores of the sheet-like base material. An electrical laminate containing a portion of resin material.