Blind hole type flexible circuit board

Abstract

The utility model discloses a blind hole type flexible circuit board, comprising a substrate layer, an isolation layer covering the surface of the substrate layer, a copper foil layer covering the outer surface of the isolation layer, and a film covering layer covering the outer surface of the copper foil layer, the copper foil layer is provided with lines, the film covering layer is provided with at least two first through holes, and the first through holes are communicated with the isolation layer. A second through hole communicated with the first through hole is formed in the copper foil layer, and the first through hole and the second through hole are combined to form a horn shape with a small inner end diameter and a large outer end diameter; third through holes are formed in the isolation layer and the substrate layer; and a transverse through groove communicated with the two third through holes is formed in the surface of the isolating layer. According to the utility model, the structure arrangement is reasonable, the copper foil layer is provided with the second through hole, the film coating layer is provided with the first through hole, the two through holes are combined to form a horn shape, the isolation layer and the substrate layer are provided with the third through hole communicated with the second through hole, and the isolation layer is provided with the transverse through groove, so that the circulation of an electroplating solution is facilitated; and the machining efficiency and the electroplating quality can be improved, the applicability is high, and the practicability is good.

Description

Technical Field

[0001] The utility model belongs to the technical field of flexible circuit boards, and in particular relates to a blind hole type flexible circuit board. Background Art

[0002] A multi-layer flexible circuit board is a flexible printed circuit board with multiple layers of circuits. It is composed of multiple layers of flexible substrates and conductive layers. The layers of circuits are connected together by adhesives, copper cladding layers, and pads.

[0003] In the prior art, when a multi-layer flexible circuit board is electroplated during processing, the blind holes of the multi-layer flexible circuit board composed of multiple layers are deep and small in diameter. Due to the surface tension of the liquid, it is not easy for the electroplating liquid to enter the tiny blind holes, which easily leads to poor circulation of the electroplating liquid, affecting the yield rate of the multi-layer flexible circuit board processing and reducing the processing efficiency, so the applicability and practicality are limited. Utility Model Content

[0004] The utility model aims to provide a blind hole type flexible circuit board which has a reasonable structure and is conducive to improving processing efficiency.

[0005] The technical solution to achieve the purpose of the utility model is a blind hole type flexible circuit board, comprising a substrate layer, an isolation layer covered on the surface of the substrate layer, a copper foil layer covered on the outer surface of the isolation layer, and a coating layer covered on the outer surface of the copper foil layer, wherein a circuit is arranged on the copper foil layer, at least two first through holes are arranged on the coating layer, and a second through hole connected to the first through hole is arranged on the copper foil layer, wherein the first through hole and the second through hole are combined to form a trumpet shape with a small inner end diameter and a large outer end diameter;

[0006] The isolation layer and the substrate layer are provided with a third through hole connected with the second through hole;

[0007] The diameter of the third through hole is 1 / 2 of the diameter of the second through hole, and the third through hole is concentrically arranged with the second through hole;

[0008] A transverse through groove connecting the two third through holes is arranged on the surface of the isolation layer.

[0009] Further preferably, a funnel-shaped transition hole is provided at the connection between the third through hole and the second through hole.

[0010] Further preferably, a conductive carbon powder layer is attached to the inner wall of the second through hole;

[0011] The outer surface of the conductive carbon powder layer is provided with a silver-plated layer.

[0012] Further preferably, the width of the transverse through groove matches the diameter of the third through hole.

[0013] More preferably, the substrate layer is a polyimide substrate.

[0014] More preferably, the isolation layer is an aluminum film material layer.

[0015] More preferably, the substrate layer, the isolation layer, the copper foil layer and the coating layer are all connected by an adhesive layer and pressed into shape.

[0016] The utility model has positive effects: the structure of the utility model is reasonably arranged, by arranging a second through hole on the copper foil layer, arranging a first through hole on the coating layer, and the two through holes are combined into a trumpet shape, and a third through hole connected to the second through hole is provided on the isolation layer and the substrate layer, and at the same time, a transverse through groove is provided on the isolation layer, which is beneficial to the circulation of the electroplating liquid, can improve the processing efficiency and the quality of the electroplating, and has strong applicability and good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to make the content of the utility model easier to understand, the utility model is further described in detail below according to specific embodiments and in conjunction with the accompanying drawings, wherein:

[0018] Figure 1 It is a structural schematic diagram of the utility model;

[0019] Figure 2 for Figure 1 The enlarged structural diagram at A in the middle;

[0020] Figure 3 It is a schematic diagram of the specific structure of the isolation layer in the utility model.

[0021] Reference numerals: substrate layer 1 , isolation layer 2 , copper foil layer 3 , coating layer 4 , adhesive layer 5 , first through hole 6 , second through hole 7 , third through hole 8 , transverse through groove 9 , funnel-shaped transition hole 10 . DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0023] Example

[0024] See Figures 1 to 3As shown, a blind hole type flexible circuit board includes a substrate layer 1, an isolation layer 2 covered on the surface of the substrate layer, a copper foil layer 3 covered on the outer surface of the isolation layer, and a coating layer 4 covered on the outer surface of the copper foil layer. The copper foil layer is provided with a circuit. In this embodiment, the substrate layer is a polyimide substrate. The isolation layer is an aluminum film material layer. The substrate layer, the isolation layer, the copper foil layer, and the coating layer are all connected and pressed together by an adhesive layer 5.

[0025] In actual application, at least two first through holes 6 are provided on the coating layer, and a second through hole 7 connected to the first through hole is provided on the copper foil layer. The first through hole and the second through hole are combined to form a trumpet shape with a small inner diameter and a large outer diameter; at the same time, a third through hole 8 connected to the second through hole is provided on the isolation layer and the substrate layer; the diameter of the third through hole is 1 / 2 of the diameter of the second through hole, and the third through hole is concentrically arranged with the second through hole; the surface of the isolation layer is provided with a transverse through groove 9 connecting the two third through holes. In this embodiment, the width of the transverse through groove matches the diameter of the third through hole. The first through hole, the second through hole and the third through hole constitute a blind hole, which can realize electrical connection between different layers, and can also realize signal transmission and connection, improve wiring sealing and performance, and can also increase the mechanical strength and stability of the flexible circuit board to prevent its deformation.

[0026] In actual application, a funnel-shaped transition hole 10 is provided at the connection between the third through hole and the second through hole. A conductive carbon powder layer is attached to the inner wall of the second through hole; and a silver-plated layer is provided on the outer surface of the conductive carbon powder layer. Since the conductive carbon powder layer and the silver-plated layer are very thin, they are not shown in the figure, but it does not affect the understanding and implementation of the technicians. The silver-plated layer can ensure the effectiveness of electrical conduction.

[0027] The utility model has positive effects: the structure of the utility model is reasonably arranged, by arranging a second through hole on the copper foil layer, arranging a first through hole on the coating layer, and the two through holes are combined into a trumpet shape, and a third through hole connected to the second through hole is provided on the isolation layer and the substrate layer, and at the same time, a transverse through groove is provided on the isolation layer, which is beneficial to the circulation of the electroplating liquid, can improve the processing efficiency and the quality of the electroplating, and has strong applicability and good practicality.

[0028] The standard parts used in this embodiment can be purchased directly from the market, and the non-standard structural components recorded in the specification can also be directly processed according to existing technical common sense. At the same time, the connection method of each component adopts the mature conventional means in the prior art, and the machinery, parts and equipment all adopt the conventional models in the prior art, so no specific description will be given here.

[0029] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still belong to the protection scope of the present invention.

Claims

1. A blind hole type flexible circuit board, comprising a substrate layer, an isolation layer covered on the surface of the substrate layer, a copper foil layer covered on the outer surface of the isolation layer, and a coating layer covered on the outer surface of the copper foil layer, wherein a circuit is arranged on the copper foil layer, characterized in that: The coating layer is provided with at least two first through holes, the copper foil layer is provided with a second through hole connected to the first through hole, and the first through hole and the second through hole are combined to form a trumpet shape with a small inner end diameter and a large outer end diameter; The isolation layer and the substrate layer are provided with a third through hole connected with the second through hole; The diameter of the third through hole is 1 / 2 of the diameter of the second through hole, and the third through hole is concentrically arranged with the second through hole; A transverse through groove connecting the two third through holes is arranged on the surface of the isolation layer.

2. A blind hole type flexible circuit board according to claim 1, characterized in that: A funnel-shaped transition hole is provided at the connection between the third through hole and the second through hole.

3. A blind hole type flexible circuit board according to claim 2, characterized in that: A conductive carbon powder layer is attached to the inner wall of the second through hole; The outer surface of the conductive carbon powder layer is provided with a silver-plated layer.

4. The blind hole type flexible circuit board according to claim 1, characterized in that: The width of the transverse through groove matches the diameter of the third through hole.

5. The blind hole type flexible circuit board according to claim 1, characterized in that: The substrate layer is a polyimide substrate.

6. The blind hole type flexible circuit board according to claim 1, characterized in that: The isolation layer is an aluminum film material layer.

7. The blind hole type flexible circuit board according to claim 1, characterized in that: The substrate layer, the isolation layer, the copper foil layer and the coating layer are all connected by an adhesive layer and pressed into shape.

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