A non-silicon release film for laminating flexible circuit boards

Abstract

This utility model discloses a non-silicone release film for laminating flexible circuit boards, comprising a first release film, a second release film, and a buffer layer. The first and second release films are separated by a core area and a peripheral area, both containing a substrate layer and a release layer opposite each other along their thickness. The buffer layer is located in the core area and is close to the substrate layer. Several receiving grooves are provided on the surfaces of the substrate layer and the buffer layer adjacent to each other. At least one surface of the buffer layer is provided with a first adhesive layer distributed in a dotted and / or striped pattern. The first adhesive layer is connected to the opposite substrate layer, and the gaps between adjacent first adhesive layers are connected to the receiving grooves along the thickness. The peripheral area is either a blank layer or has a second adhesive layer. The first release film, the buffer layer, and the second release film are fixedly connected. The combination of the first and second adhesive layers improves the bonding strength between the layers; the receiving grooves combined with the dotted and / or striped first adhesive layer effectively prevent excessive adhesive overflow.

Description

Technical Field

[0001] This utility model relates to the field of thin film technology, and in particular to a non-silicon release film for laminating flexible circuit boards. Background Technology

[0002] For the hot pressing process of multilayer circuit boards with thick inner copper layers (above 50μm), the hot pressing of multilayer circuit boards that require sufficient flow and filling of prepreg resin necessitates the use of a gasket film with good conformability and flowability as a buffer film for pressing, providing good conformability and release properties for the hot pressing of multilayer circuit boards.

[0003] Existing release films for rigid-flex PCB lamination consist of upper and lower release films and a middle plastic core layer. In some existing designs, the three layers are naturally stacked, rather than being a composite film. This allows for easy displacement between layers, leading to problems such as wrinkling of the circuit board during hot pressing. In other designs, the three layers are fixed by heating and ultrasonic waves to melt and penetrate the surface release film. However, the middle layer melts and overflows at high temperatures, causing it to stick to the circuit board and steel plate, affecting circuit board quality, contaminating the hot press, and making disassembly difficult.

[0004] Therefore, it is necessary to improve the non-silicon release film used for laminating flexible circuit boards in the existing technology. Utility Model Content

[0005] The purpose of this invention is to overcome the defects in the existing technology and provide a non-silicone release film for laminating flexible circuit boards. The combination of the first adhesive layer and the second adhesive layer improves the bonding strength between the layers. The first adhesive layer, which is distributed in a dotted and / or striped pattern, is combined with a receiving groove to effectively prevent excessive adhesive overflow.

[0006] To achieve the above-mentioned technical effects, the technical solution of this utility model is: a non-silicone release film for laminating flexible circuit boards, comprising:

[0007] The first release film and the second release film, which include a core area and a peripheral area between them, each contain a substrate layer and a release layer that are opposite to each other along the layer thickness;

[0008] A buffer layer is located in the filled core area and is close to the substrate layer;

[0009] The substrate layer and the buffer layer are provided with a plurality of receiving grooves on their surfaces close to each other. At least one surface of the buffer layer is provided with a first adhesive layer distributed in a dotted and / or striped pattern. The first adhesive layer is connected to the opposite substrate layer. The gap between adjacent first adhesive layers is connected to the receiving groove along the layer thickness.

[0010] The peripheral area is either a blank layer or has a second adhesive layer, and the first release film, the buffer layer, and the second release film are fixedly connected.

[0011] A preferred technical solution is that the second adhesive layer is disposed on the side edges of both sides of the substrate layer and extends longitudinally.

[0012] A preferred technical solution is that the extension direction of the strip-shaped first adhesive layer is perpendicular to the extension direction of the second adhesive layer, and the arrangement direction of the strip-shaped first adhesive layer is consistent with the extension direction of the second adhesive layer.

[0013] A preferred technical solution is that the depth of the receiving groove is 30% to 50% of the thickness of the substrate layer, and the thickness of the substrate layer is 100 to 150 micrometers.

[0014] A preferred technical solution is that the thickness of the second adhesive layer is equal to the total thickness of the buffer layer and the first adhesive layer.

[0015] The preferred technical solution is that the buffer layer is made of polyethylene.

[0016] The preferred technical solution is that both the first adhesive layer and the second adhesive layer are made of polyurethane pressure-sensitive adhesive.

[0017] A preferred technical solution is that the release layer is a non-silicon release layer.

[0018] This utility model relates to a non-silicone release film for laminating flexible circuit boards. It improves the bonding strength of the first release film, the second release film, and the buffer layer through a first adhesive layer or a combination of the first adhesive layer and the second adhesive layer. By using several receiving grooves set on the surface of the substrate layer near the buffer layer, combined with the first adhesive layer which is distributed in a dotted and / or striped pattern, the buffer layer flows into the gap between the receiving grooves and the adjacent first adhesive layer when it is in a molten state, thereby effectively preventing the occurrence of a large amount of adhesive overflow. Attached Figure Description

[0019] Figure 1 This is a transverse cross-sectional view of the first adhesive layer of the non-silicone release film strip used for laminating flexible circuit boards according to this utility model;

[0020] Figure 2 This is a schematic diagram of another state of the second adhesive layer in the non-silicone release film for laminating flexible circuit boards according to this utility model;

[0021] Figure 3 yes Figure 2 Top view with the second release film removed;

[0022] Figure 4 This is a transverse cross-sectional view of the non-silicone release film dotted first adhesive layer for laminating flexible circuit boards according to this utility model;

[0023] Figure 5 yes Figure 4 Top view with the second release film removed.

[0024] In the figure: 1. First release film; 2. Second release film; 3. Buffer layer; 10. Substrate layer; 11. Release layer; 12. Receiving groove; 31. First adhesive layer; 22. Second adhesive layer. Detailed Implementation

[0025] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0026] The terms "core area," "peripheral side," and "side edge" are used with reference to the normal operating state of the non-silicone release film for laminating flexible circuit boards. They are used only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0027] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0028] Figure 3 and Figure 5 In the text, 12 represents the receiving groove on the surface of the substrate layer 10 of the first release film 1, indicated by a solid coil; Figure 3 The dashed line represents the strip-shaped first adhesive layer disposed on the surface of the buffer layer 3 facing the substrate layer 10 of the first release film 1; Figure 5 The dashed circle in the middle indicates a dotted first adhesive layer disposed on the surface of the buffer layer 3 facing the substrate layer 10 of the first release film 1.

[0029] like Figures 1-5 As shown, the non-silicone release film for laminating flexible circuit boards of this utility model includes a first release film 1, a second release film 2, and a buffer layer 3. The first release film 1 and the second release film 2 include a core area and a peripheral area, both containing a substrate layer 10 and a release layer 11 that are opposite each other along the layer thickness. The buffer layer 3 is located in the core area and is close to the substrate layer 10. The surface of the substrate layer 10 that is close to the buffer layer 3 is provided with a plurality of receiving grooves 12. At least one surface of the buffer layer 3 is provided with a first adhesive layer 31 distributed in a dotted and / or striped manner. The first adhesive layer 31 is connected to the opposite substrate layer 10, and the gap between adjacent first adhesive layers 31 is connected to the receiving grooves 12 along the layer thickness. The peripheral area is a blank layer or is provided with a second adhesive layer 22. The first release film 1, the buffer layer 3, and the second release film 2 are fixedly connected.

[0030] The bonding strength between the first release film 1, the second release film 2, and the buffer layer 3 is improved by the first adhesive layer 31 or the combination of the first adhesive layer 31 and the second adhesive layer 22; the first adhesive layer 31, which is distributed in a dotted and / or striped manner, is combined with a plurality of receiving grooves 12 provided on the surface of the substrate layer 10 near the buffer layer 3, and when the buffer layer 3 is in a molten state, it flows into the gap between the receiving grooves 12 and the adjacent first adhesive layer 31, thereby effectively preventing the occurrence of a large amount of adhesive overflow.

[0031] The receiving groove 12 provided on the surface of the substrate layer 10 is obtained by hot pressing with a mold, laser drilling or other common methods.

[0032] Specifically, for the sake of production continuity, the peripheral side area is located on both sides of the first release film 1 and the second release film 2, and extends longitudinally therein. The filling core area is sandwiched between the peripheral side areas on both sides.

[0033] In some embodiments, a first adhesive layer 31 distributed in a dotted and / or striped pattern is provided on one surface of the buffer layer 3, and a second adhesive layer 22 is provided in the peripheral area to ensure a fixed connection between the first release film 1, the buffer layer 3 and the second release film 2.

[0034] In other embodiments, the buffer layer 3 has a first adhesive layer 31 distributed in a dotted and / or striped pattern on both surfaces, and the peripheral area is a blank layer, which ensures a fixed connection between the first release film 1, the buffer layer 3 and the second release film 2. The second adhesive layer 22 can be omitted, simplifying the process.

[0035] The first adhesive layer 31 and the buffer layer 3 are formed by coating an adhesive onto a release film with uneven surfaces to form a strip-shaped first adhesive layer that matches the uneven surfaces. The strip-shaped first adhesive layer is combined with the buffer layer 3. When in use, the release film is peeled off. A dot-shaped first adhesive layer is set on the surface of the buffer layer 3 by a dispensing machine.

[0036] The second adhesive layer 22 is disposed on both sides of the side edges of the substrate layer 10 and extends longitudinally. The second adhesive layer 22 is disposed in such a manner that an adhesive coating unit is located below the guiding channel of the first release film 1, with the coating unit positioned on both sides of the guiding channel. The substrate layer 10 of the first release film 1 faces the coating unit, and the second adhesive layer 22 is obtained after drying and curing. The width of the second adhesive layer 22 is smaller than the width of the peripheral area, such as... Figures 1-5 As shown.

[0037] To prevent the buffer layer from flowing everywhere in its molten state, the extension direction of the strip-shaped first adhesive layer is perpendicular to the extension direction of the second adhesive layer 22, and the arrangement direction of the strip-shaped first adhesive layer is consistent with the extension direction of the second adhesive layer 22. This arrangement, with the first adhesive layer 31 and the second adhesive layer 22 surrounding the buffer layer 3, simplifies the processing technology; it can be cut along one of the first adhesive layers during use.

[0038] When the dotted first adhesive layer and the buffer layer 3 are combined, after transverse cutting, the cut surface between the first release film 1 and the second release film 2 exposes the buffer layer 3 and the dotted first adhesive layer. After cutting, the side length of the gasket is greater than the side length of the circuit board, which reduces the heat on the edge and reduces the amount of flow of the buffer layer 3. At the same time, the filling core area is in direct contact with the circuit board. The buffer layer 3 is heated and melts to fill the gap between the receiving groove 12 and the adjacent first adhesive layer 31, forming a slightly inclined state, that is, the peripheral area and the transverse cut end are slightly raised, which makes it less likely for the buffer layer 3 to melt and overflow the edge.

[0039] The depth of the receiving groove 12 is 30% to 50% of the thickness of the substrate layer 10, and the thickness of the substrate layer 10 is 100 to 150 micrometers.

[0040] To improve the overall flatness of the membrane structure, the thickness of the second adhesive layer 22 is equal to the total thickness of the buffer layer 3 and the first adhesive layer 31.

[0041] The buffer layer 3 is made of polyethylene, which has low production costs and good cushioning effect. The first adhesive layer 31 and the second adhesive layer 22 are both made of polyurethane pressure-sensitive adhesive, which has good high-temperature resistance. The release layer 11 is a non-silicone release layer, which can be obtained by coating with existing non-silicone release agents. Because flexible circuit boards are laminated under high temperature and pressure, the low molecular weight siloxanes or silicone oil components in traditional silicone release agents may migrate or volatilize. These trace amounts of silicone substances can easily transfer to the product surface, affecting its performance and quality. The substrate layer 10 is made of PET.

[0042] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A non-silicone release film for laminating flexible circuit boards, comprising: The first release film and the second release film, which include a core area and a peripheral area between them, each contain a substrate layer and a release layer that are opposite to each other along the layer thickness; A buffer layer is located in the filled core area and is close to the substrate layer; The feature is that a plurality of receiving grooves are provided on the surface of the substrate layer and the buffer layer that are close to each other, and at least one surface of the buffer layer is provided with a first adhesive layer distributed in a dotted and / or striped manner, the first adhesive layer is connected to the opposite substrate layer, and the gap between adjacent first adhesive layers is connected to the receiving groove along the layer thickness. The peripheral area is either a blank layer or has a second adhesive layer, and the first release film, the buffer layer, and the second release film are fixedly connected.

2. The non-silicone release film for laminating flexible circuit boards according to claim 1, characterized in that, The second adhesive layer is disposed on the side edges of both sides of the substrate layer and extends longitudinally.

3. The non-silicone release film for laminating flexible circuit boards according to claim 1, characterized in that, The extension direction of the strip-shaped first adhesive layer is perpendicular to the extension direction of the second adhesive layer, and the arrangement direction of the strip-shaped first adhesive layer is consistent with the extension direction of the second adhesive layer.

4. The non-silicone release film for laminating flexible circuit boards according to claim 1, characterized in that, The depth of the receiving groove is 30% to 50% of the thickness of the substrate layer, and the thickness of the substrate layer is 100 to 150 micrometers.

5. The non-silicone release film for laminating flexible circuit boards according to claim 1, characterized in that, The thickness of the second adhesive layer is equal to the total thickness of the buffer layer and the first adhesive layer.

6. The non-silicone release film for laminating flexible circuit boards according to claim 1, characterized in that, The buffer layer is made of polyethylene.

7. The non-silicone release film for laminating flexible circuit boards according to claim 1, characterized in that, Both the first adhesive layer and the second adhesive layer are made of polyurethane pressure-sensitive adhesive.

8. The non-silicone release film for laminating flexible circuit boards according to claim 1, characterized in that, The release layer is a non-silicon release layer.

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