CN202396084U - flexible circuit board - Google Patents

Abstract

A flexible circuit board comprises a flexible substrate and at least one circuit layer; the flexible substrate is provided with an upper surface; the circuit layer is arranged on the upper surface and partially covers the upper surface, wherein the circuit layer comprises a sputtering metal pattern layer and a plating metal pattern layer, and the sputtering metal pattern layer is connected between the plating metal pattern layer and the flexible substrate and is contacted with the plating metal pattern layer and the flexible substrate. The utility model discloses with the help of the formation on sputter metal pattern layer, can reduce to take place that patterned light resistance layer remains and walk the situation of line short circuit to maintain or improve the qualification rate of compliance circuit board.

Description

flexible circuit board

technical field

The utility model relates to a circuit board, in particular to a flexible circuit board.

Background technique

Today's flexible circuit board (Flexible Circuit Board) has been widely used in electronic products, and has multiple connection pads (Pads) to electrically connect and assemble multiple electronic components and chips (Chips). Flexible printed circuit boards are generally manufactured through the following methods. First, cover the surface of the insulating flexible board with photoresist. Then, the photoresist is exposed and developed to form a patterned photoresist layer, wherein the patterned photoresist layer has a plurality of openings exposing part of the surface of the insulating flexible board. Next, chemical plating (Chemical plating, also known as electroless plating, Electroplating) and electroplating are sequentially performed to form a circuit layer on the insulating flexible board. Afterwards, etching and stripping are performed to remove the patterned photoresist layer.

However, after etching, part of the patterned photoresist layer may be covered by the remaining electroplated metal layer, which makes it difficult to remove the patterned photoresist layer from the insulating flexible sheet, so that after stripping, the patterned photoresist layer remains. Photoresist remains. In addition, the electroplated metal layer covering the remaining patterned photoresist layer may short-circuit two adjacent traces of the circuit layer, resulting in a decrease in the yield of the flexible circuit board.

Utility model content

The utility model provides a flexible circuit board, which can reduce the occurrence of the above-mentioned patterned photoresist layer residue and wiring short circuit.

The utility model provides a flexible circuit board, which includes: a flexible substrate and at least one circuit layer. The flexible substrate has an upper surface. The circuit layer is arranged on the upper surface and partially covers the upper surface, wherein the circuit layer includes a sputtered metal pattern layer and an electroplated metal pattern layer, and the sputtered metal pattern layer is connected between the electroplated metal pattern layer and the flexible substrate, and Contact electroplated metal pattern layer and flexible substrate.

In other words, the utility model provides a flexible circuit board, which includes: a flexible substrate with an upper surface; and at least one circuit layer configured on the upper surface and partially covering the upper surface, wherein the The circuit layer includes a sputtered metal pattern layer and an electroplated metal pattern layer, and the sputtered metal pattern layer is connected between the electroplated metal pattern layer and the flexible substrate, and contacts the electroplated metal pattern layer and the flexible substrate .

In an embodiment of the present invention, the thickness of the circuit layer is between 3 microns and 100 microns.

In an embodiment of the present invention, the above-mentioned flexible substrate is a flexible circuit substrate, and includes: a core insulating layer, at least one polymer material layer and at least one inner circuit layer. The inner circuit layer is arranged between the polymer material layer and the core insulating layer, wherein the polymer material layer covers the inner circuit layer, and is arranged between the inner circuit layer and the circuit layer, and the circuit layer partially covers the polymer material layer .

In an embodiment of the present invention, the above-mentioned flexible circuit board further includes at least one conductive blind hole structure, the conductive blind hole structure penetrates the polymer material layer, and connects the inner circuit layer and the circuit layer.

In an embodiment of the present invention, the above-mentioned polymer material layer has at least one blind hole, and the conductive blind hole structure is arranged in the blind hole, and includes a seed layer and an electroplated metal post, wherein the seed layer covers and contacts One wall of a blind via, while the plated metal post is surrounded by a seed layer.

In an embodiment of the present invention, the above-mentioned flexible substrate is a polymer material sheet.

In an embodiment of the present invention, the number of the above-mentioned circuit layers is two, and the flexible substrate further has a lower surface opposite to the upper surface, the two circuit layers are respectively arranged on the upper surface and the lower surface, and Partially cover the upper surface and the lower surface, respectively.

In an embodiment of the present invention, the above-mentioned flexible circuit board further includes at least one conductive via structure, which penetrates the flexible substrate and connects the two circuit layers.

In an embodiment of the present invention, the above-mentioned flexible substrate has at least one through hole, and the conductive through hole structure is disposed in the through hole, and includes a seed layer and an electroplated metal post, wherein the seed layer covers and contacts the through hole A hole wall, while the plated metal pillar is surrounded by the seed layer.

Based on the above, by means of the formation of the sputtered metal pattern layer, the present invention can reduce the occurrence of the patterned photoresist layer residue and the short circuit of the wiring, thereby maintaining or improving the yield of the flexible circuit board.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific examples are given together with the accompanying drawings and described in detail as follows.

Description of drawings

1 is a schematic cross-sectional view of a flexible circuit board according to a first embodiment of the present invention;

2 is a schematic cross-sectional view of a flexible circuit board according to a second embodiment of the present invention;

3 to 6 are schematic cross-sectional views of a method for manufacturing a flexible circuit board according to a second embodiment of the present invention.

[Description of reference signs of main components]

B1: blind hole

H1, H2: through hole

W1, W2, W3: hole wall

1, 2: Flexible circuit board

10, 20: flexible substrate

12: Circuit layer

14, 16: Conductive via structure

18: Conductive blind hole structure

22: Patterned photoresist layer

100: upper surface

102: lower surface

104: Core insulation

106: polymer material layer

108: inner circuit layer

120: sputtering metal pattern layer

122: electroplating metal pattern layer

124: sputtered metal layer

126: electroplating metal layer

142, 162, 182: seed layer

144, 164, 184: electroplated metal column

Detailed ways

In order to fully understand the utility model, preferred embodiments will be listed below and described in detail with accompanying drawings, but the following embodiments are not intended to limit the utility model.

first embodiment

The structures of the flexible circuit boards according to the various embodiments of the present invention will be described in detail below according to FIG. 1 and FIG. 2 in sequence.

FIG. 1 is a schematic cross-sectional view of a flexible circuit board according to a first embodiment of the present invention. Please refer to FIG. 1 , a flexible circuit board 1 includes a flexible substrate 10 and at least one circuit layer 12 . Flexible substrate 10 is a kind of insulating substrate, and can be polymer material sheet, and it is for example made of vinyl terephthalate (Polyethylene Terephthalate, PET), polyimide (Polyimide, PI), photosensitive polyimide Imine (Photosensitive Polyimide, PSPI) or polycarbonate (Polycarbonate, PC), liquid crystal polymer (Liquid Crystal Polyester, LCP) or polytetrafluoroethylene (Polytetrafluoroethylene, PTFE) and other materials.

In this embodiment, the flexible circuit board 1 may include two circuit layers 12 , and the flexible substrate 10 has an upper surface 100 and a lower surface 102 opposite to the upper surface 100 . These circuit layers 12 partially cover the upper surface 100 and the lower surface 102 respectively, and each circuit layer 12 includes a sputtered metal pattern layer 120 and an electroplated metal pattern layer 122, or an electroless deposition pattern layer and an electroplated metal pattern layer 122, and the sputtered metal pattern layer 122 The patterned metallization layer 120 or the chemically deposited patterned layer is connected between the patterned metallization layer 122 and the flexible substrate 10 , and contacts the patterned metallization layer 122 and the flexible substrate 10 . In addition, the thickness of the circuit layer 12 can be between 3 microns and 100 microns, and the material of the sputtered metal pattern layer 120 is, for example, chromium, gold, nickel, copper, and for the convenience of description, the circuit layer 12 of this embodiment is The sputtered metal pattern layer 120 and the electroplated metal pattern layer 122 are taken as examples for illustration.

It should be noted that, in other embodiments, the number of the circuit layer 12 may be only one, and the circuit layer 12 may only be disposed on the upper surface 100 or the lower surface 102 . However, the configuration and quantity of the circuit layers 12 in FIG. 1 are only for illustration, and this embodiment is not limited to FIG. 1 .

The flexible circuit board 1 may further include at least one conductive via structure 14 . The conductive via structure 14 runs through the flexible substrate 10 and connects these circuit layers 12, wherein the flexible substrate 10 has at least one through hole H1, and the conductive via structure 14 is disposed in the through hole H1 and includes a seed layer (Seed Layer ) 142 and an electroplated metal pillar 144, wherein the seed layer 142 covers and contacts a hole wall W1 of the through hole H1, that is, the seed layer 142 is in contact with the flexible substrate 10, and the electroplated metal pillar 144 is surrounded by the seed layer 142.

It is worth mentioning that the material of the seed layer 142 may not only include metal materials such as copper and silver, but also include carbon glue, copper glue, silver glue, omni-directional conductive glue, and the like. In addition, the circuit layer 12 is respectively disposed on the upper surface 100 and the lower surface 102 of the flexible substrate 10, and the conductive via structure 14 is connected to the second circuit layer 12 of the flexible substrate 10 to transmit electrical signals between these circuit layers 12. .

second embodiment

FIG. 2 is a schematic cross-sectional view of a flexible circuit board according to a second embodiment of the present invention. Please refer to Fig. 2, the present embodiment provides another flexible circuit board 2, wherein the flexible circuit board 1 in Fig. 1 and the flexible circuit board 2 in Fig. 2 are similar in structure, and the following will describe The same elements included in both are denoted by the same reference numerals.

The difference between the flexible circuit boards 1 and 2 is that the flexible substrate 20 is a flexible circuit substrate and includes a core insulating layer 104 , at least one inner circuit layer 108 and at least one polymer material layer 106 . Taking FIG. 2 as an example, the flexible substrate 20 may include two polymer material layers 106 , two inner circuit layers 108 and two circuit layers 12 . However, it should be noted that in other embodiments, the flexible substrate 20 may only include one layer of polymer material 106, one layer of inner circuit layer 108 and one layer of circuit layer 12, so the polymer material in FIG. The numbers of the layers 106 , the inner circuit layer 108 and the circuit layer 12 are only for illustration, and the present embodiment is not limited to FIG. 2 .

The materials of the polymer material layer 106 and the core insulating layer 104 are, for example, polyethylene terephthalate (PET), polyimide (PI) or polycarbonate (PC), liquid crystal polymer (LCP) or polycarbonate (PC). It is made of materials such as Polytetrafluoroethylene (PTFE) or photosensitive polyimide (PSPI). The inner circuit layer 108 is disposed between the polymer material layer 106 and the core insulating layer 104, wherein the polymer material layer 106 covers the inner circuit layer 108, and is disposed between the inner circuit layer 108 and the circuit layer 12, and the circuit Layer 12 partially covers polymeric material layer 106 . In addition, the polymer material layer 106 may partially or completely cover the core insulating layer 104. For example, the polymer material layer 106 in FIG. 2 completely covers the core insulating layer 104. The polymer material layer 106 in FIG. 2.

The flexible circuit board 2 may further include at least one conductive via structure 16 . The conductive via structure 16 penetrates the flexible substrate 20 and connects the circuit layers 12 to transmit electrical signals between the circuit layer 12 and the inner circuit layer 108 . The flexible substrate 20 has at least one through hole H2, and the conductive via structure 16 is disposed in the through hole H2, and includes a seed layer 162 and an electroplated metal pillar 164, wherein the seed layer 162 covers and contacts a hole wall of the through hole H2. W2 , that is, the seed layer 162 is in contact with the flexible substrate 20 , and the electroplated metal post 164 is surrounded by the seed layer 162 .

The flexible circuit board 2 may further include at least one conductive blind hole structure 18 , for example, the flexible circuit board 2 shown in FIG. 2 may include two conductive blind hole structures 18 . The conductive blind via structure 18 penetrates the polymer material layer 106 and connects the inner circuit layer 108 and the circuit layer 12 to transmit electrical signals between the inner circuit layer 108 and the circuit layer 12 . Each polymer material layer 106 can have at least one blind hole B1, and the conductive blind hole structure 18 is disposed in the blind hole B1, and includes a seed layer 182 and an electroplated metal post 184, wherein the seed layer 182 covers and contacts the blind hole A hole wall W3 of B1, and the plated metal post 184 is surrounded by the seed layer 182 .

The above is the introduction of the structure of the flexible circuit board in various embodiments of the present invention. Next, the flexible circuit board 2 shown in FIG. Circuit board manufacturing process.

3 to 6 are schematic cross-sectional views of a method for manufacturing a flexible circuit board according to a second embodiment of the present invention. Please refer to FIG. 3 , firstly, a flexible substrate 20 is provided, wherein the flexible substrate 20 includes two polymer material layers 106, an inner circuit layer 108 and a core insulating layer 104, and the core insulating layer 104 is located at a height of two layers. Between the molecular material layers 106 , and each inner circuit layer 108 is disposed between the core insulating layer 104 and the polymer material layer 106 . Next, at least one through hole H2 is formed on the flexible substrate 20 , wherein the through hole H2 partially exposes the core insulating layer 104 and the polymer material layer 106 . The method of forming the through hole H2 may include mechanical drilling or laser ablation (Laser Ablation).

Next, a plurality of blind holes B1 are formed on the polymer material layer 106 , wherein the blind holes B1 partially expose the inner circuit layer 108 . The method of forming these blind holes B1 may include laser ablation, or lithography and etching. If the blind holes B1 are formed by laser ablation, after the blind holes B1 are formed, the blind holes B1 can be desmeared or surface treated with plasma, The surface of the part of the inner circuit layer 108 exposed by the blind hole B1 and the hole wall W3 of the blind hole B1 are cleaned. Afterwards, sputtering is performed to form a sputtered metal layer 124 on the upper surface 100, the lower surface 102 or the upper surface 100 and the lower surface 102 of the flexible substrate 20, wherein the material of the sputtered metal layer 124 is, for example, chromium, gold, nickel, copper. It is worth mentioning that the sputtered metal layer 124 in this embodiment can be replaced by an electroless deposition layer.

Please refer to FIG. 4, and then, form seed layers 162, 182 on the hole wall W2 of the through hole H1 and the hole wall W3 of the blind hole B1 respectively, wherein the seed layer 162 covers the hole wall W2 of the through hole H2 in an all-round way, and the seed layer The layer 182 completely covers the bottom of the blind hole B1 and the hole wall W3. In addition, the seed layers 162, 182 can be formed by electroless plating, and the material of the seed layers 162, 182 can not only include metal materials, such as: copper, silver, but also include carbon glue, copper glue, silver glue, all-round Conductive glue, etc.

Next, the sputtered metal layer 124 and the seed layers 162, 182 are electroplated to form an electroplated metal layer 126 and electroplated metal pillars 164, 184, thereby forming the conductive via structure 16 and the conductive blind hole structure 18, wherein the electroplated metal The layer 126 may be formed by full plate plating, and the plated metal pillars 164, 184 may be formed by through hole plating (Plating Through Hole, PTH). Although the electroplated metal layer 126 can be formed by full board electroplating, and the electroplated metal posts 164, 184 can be formed by through-hole electroplating, but in actual situations, the electroplated metal layer 126, the electroplated metal posts 164 and 184 can be formed in the same Formed during the electroplating process. In addition, after the electroplating metal layer 126 is formed, the electroplating metal layer 126 may be micro-etched.

Please refer to FIG. 5, then, a photoresist layer (not shown) is formed on the electroplated metal layer 126, and the photoresist layer (not shown) is exposed and developed to form a patterned photoresist layer 22, and The patterned photoresist layer 22 partially covers the electroplating metal layer 126 . In addition, the patterned photoresist layer 22 can be formed by exposing and developing a dry film or a wet film.

Please refer to Figure 5 and Figure 6. Afterwards, the patterned photoresist layer 22 is used as an etching mask to etch the electroplated metal layer 126 and part of the sputtered metal layer 124 exposed by the patterned photoresist layer 22, so as to form a sputtered metal pattern layer 120 and an electroplated metal pattern. The circuit layer 12 of the layer 122, wherein the above-mentioned etching method is, for example, wet etching (Wet Etching) or dry etching (Dry Etching). Afterwards, the patterned photoresist layer 22 is removed to expose the circuit layer 12 . So far, a flexible circuit board 2 has basically been fabricated, as shown in FIG. 2 .

Based on the above, the utility model firstly forms a sputtered metal layer on the flexible substrate. Next, an electroplated metal layer is formed on the sputtered metal layer. Afterwards, a circuit layer including a sputtered metal pattern layer and an electroplated metal pattern layer is formed by using the patterned photoresist layer as a mask and etching. In this way, after the flexible circuit board is completed, the utility model can prevent the patterned photoresist layer from remaining on the flexible substrate. Compared with the known technology, the utility model can improve the situation of the short circuit caused by the coverage of the electroplated metal layer on the patterned photoresist layer, thereby maintaining or improving the qualified rate of the flexible circuit board.

The above disclosures are only preferred embodiments of the present utility model, but the present utility model is not limited by the above-mentioned embodiments, and any person of ordinary skill in the art can make some changes and adjustments without departing from the scope of the present utility model .

Claims (9)

1. A flexible circuit board, characterized in that, comprising: a flexible substrate having an upper surface; and At least one circuit layer is arranged on the upper surface and partially covers the upper surface, wherein the circuit layer includes a sputtered metal pattern layer and an electroplated metal pattern layer, and the sputtered metal pattern layer is connected to the electroplated metal pattern layer between the flexible substrate and in contact with the electroplated metal pattern layer and the flexible substrate. 2. The flexible circuit board as claimed in claim 1, wherein the thickness of the circuit layer is between 3 micrometers and 100 micrometers. 3. The flexible circuit board according to claim 1, wherein the flexible substrate is a flexible circuit substrate, and comprises: a core insulation layer; at least one polymer material layer; and At least one inner circuit layer is disposed between the polymer material layer and the core insulating layer, wherein the polymer material layer covers the inner circuit layer and is disposed between the inner circuit layer and the circuit layer, The circuit layer partially covers the polymer material layer. 4. The flexible circuit board according to claim 3, further comprising at least one conductive blind hole structure, the conductive blind hole structure penetrates the polymer material layer, and connects the inner circuit layer and the circuit layer. 5. The flexible circuit board according to claim 4, wherein the polymer material layer has at least one blind hole, and the conductive blind hole structure is disposed in the blind hole, and includes a seed layer and a The electroplated metal post, wherein the seed layer covers and contacts a hole wall of the blind hole, and the electroplated metal post is surrounded by the seed layer. 6. The flexible circuit board as claimed in claim 1, wherein the flexible substrate is a sheet of polymer material. 7. The flexible circuit board according to claim 1, wherein the number of the circuit layers is two, and the flexible substrate further has a lower surface opposite to the upper surface, and the two circuit layers respectively disposed on the upper surface and the lower surface, and partially cover the upper surface and the lower surface respectively. 8. The flexible circuit board according to claim 7, further comprising at least one conductive via structure, the conductive via structure penetrates the flexible substrate and connects the two circuit layers. 9. The flexible circuit board according to claim 8, wherein the flexible substrate has at least one through hole, and the conductive through hole structure is disposed in the through hole, and includes a seed layer and an electroplated metal pillar, wherein the seed layer covers and contacts a hole wall of the through hole, and the plated metal pillar is surrounded by the seed layer.

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