JPH084285Y2 - Double-sided coverlay film for multilayering printed circuit boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a double-sided cover lay film for use in multilayering a flexible printed circuit (FPC) substrate (hereinafter referred to as a substrate).

[Prior Art] As shown in FIG. 3, a conventional protective cover lay film for a substrate 1 is obtained by applying a semi-cured heat-resistant adhesive 3 on one surface of a heat-resistant plastic film 2 and then applying a film or The release film 4 made of paper is pressure-bonded.
A resin coat 5 is applied to the pressure-bonded surface.

In recent years, as electronic products have become lighter, thinner, shorter, and more sophisticated, and at the same time have become more sophisticated, there has been an increasing demand for a multilayer structure in which a plurality of substrates are stacked.

[Problems to be Solved by the Invention] As shown in FIG. 4, the substrate 6 is coated with a heat resistant adhesive 8 on both sides of a substrate body 7, and a metal foil 9 such as a copper foil or an aluminum foil is applied thereon. Is a structure in which is pasted. Therefore, in order to make this substrate multi-layered, for example, as shown in FIG. 5, the conventional coverlay film 1 shown in FIG. It must be layered with 10 in between. The bonding sheet 10 used at this time is, for example, as shown in FIG. 6, a release paper 11 on which a resin coat 13 is applied, which is laminated on a release film 11 via an adhesive 12,
The release film 11 and the release paper 14 are peeled off before use.

However, multilayering with such a coverlay film and a bonding sheet is a very complicated process such as punching, press molding, processing of an adhesive sheet, and pressing with a substrate to be laid on it, which requires manpower, time and cost. In addition, since there are many processes, alignment and the like are complicated, yield is lowered, and it is difficult to stabilize the quality.

[Means for Solving the Problems] The present invention has been made in order to solve such a problem, and it has a heat-resistant adhesive layer in a semi-cured state on both surfaces of a heat-resistant plastic film. A double-sided coverlay film for multilayering a printed circuit board, characterized in that a release coating film coated with resin is pressure-bonded to the layers.

 Embodiments of the present invention will be described below with reference to the drawings.

In the double-sided coverlay film 15 of the present invention shown in FIG. 1, 2 is a heat-resistant plastic film, for example, a polyimide film, and the thickness thereof may be 12.5 to 125 μm, which is selected according to the purpose of use. Reference numeral 3 denotes a heat-resistant adhesive layer in a semi-cured state, which is provided on both sides of the film and is preferably a rubber-modified epoxy resin, acrylic resin, nylon epoxy resin, or the like, and preferably has a thickness of 10 to 50 μm. Reference numeral 16 is a release film having a three-layer structure in which the resin coat 5 is applied or laminated on both sides of the base paper.

As the release film, there is a release film or release paper,
Examples of the release film include a single film such as a polyethylene film, a polypropylene film, and a TPX film, or a film surface-treated with a silicone-based release agent. As release paper, polyester on both sides of the base paper,
Suitable is coated paper coated with a release resin such as polyethylene, polypropylene, or silicone release agent, or film coated paper in which polyethylene or polypropylene film is laminated on both sides of the base paper, and the resin layer is 10 to 50 μm. It is desirable that the film or base paper has a thickness of 20 to 100 μm and a total thickness of 50 to 200 μm.

By coating both sides of the base paper with a resin, the release film has improved hygroscopicity, does not cause curling due to changes in humidity, and is suitable in terms of processability.

Next, FIG. 2 shows a case where the substrate 6 is multilayered using the double-sided coverlay film of the present invention. Sided coverlay film 15 of the present invention showing the opposing surfaces of the substrate in Figure 1 adhered peel off the release film 16, a conventional protective coverlay film 1 on the outer surface of each substrate release film 4 Peel and glue. As is clear from the figure, by using the double-sided coverlay film of the present invention, the bonding sheet becomes unnecessary as shown in the table below, the usage amount of the coverlay film is reduced, and the pressing process and the processing process are simplified. It can be achieved, and the cost is significantly reduced. Further, the following table shows the number of coverlay films and bonding sheets required to obtain the multilayer substrate of the present invention and the prior art and the number of presses required to obtain the multilayer substrate.

[Advantage of the Invention] According to the present invention, the number of steps, the amount of materials used, and the cost reduction due to the simplification of the work when the substrate is multi-layered are remarkable, and the present invention is extremely useful industrially.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a double-sided coverlay film of the present invention, FIG. 2 is an explanatory diagram when a double-sided coverlay film of the present invention is used to form a multilayer substrate, and FIG. 3 is a conventional coverlay film. Cross-sectional view, FIG. 4 is a cross-sectional view of a substrate to be multilayered,
FIG. 5 is an explanatory view when a substrate is multilayered using a conventional coverlay film, and FIG. 6 is a sectional view of a bonding sheet. 1 ... Coverlay film, 2 ... Heat-resistant plastic film, 3 ... Heat-resistant adhesive layer, 4 ... Release film, 5 ...
… Resin coat, 6 … Substrate, 7… Substrate body, 8… Heat-resistant adhesive, 9… Metal foil, 10 … Bonding sheet, 11… Release film, 12… Adhesive, 13 …… Resin coat, 14 …… Release paper, 15 …… Double-sided coverlay film, 16 …… Release film.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshitsugu Sakaguchi 1st Togada, Kamisu-cho, Kashima-gun, Ibaraki Prefecture Shin-Etsu Chemical Co., Ltd. Polymer Functional Materials Research Laboratory (56) Reference Japanese Patent Laid-Open No. 2- 202441 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A printed circuit board multilayer comprising a heat-resistant plastic film having heat-resistant adhesive layers in a semi-cured state on both sides, and a resin-coated release film is pressure-bonded to each adhesive layer. Double-sided coverlay film for chemicals.