A copper clad laminate connection structure based on thermoplastic resin base film

Abstract

The present invention relates to a copper clad laminate connection structure based on a thermoplastic resin base film. The rigid part includes a glass fiber cloth, an epoxy resin layer and a rigid copper foil, the end edge of the rigid part is provided with a window groove, the flexible part includes a thermoplastic resin base film and a flexible copper foil, the upper end face of the flexible copper foil is embedded in the bottom of the window groove, the connection part includes a connection plate provided with a fitting section, a transition section and a butt section, the fitting section abuts the glass fiber cloth upward, the butt section abuts the thermoplastic resin base film upward, the cavity formed between the transition section and the thermoplastic resin base film is filled with a semi-cured sheet, the rigid part is provided with a through hole and cooperates with a cross hole column, and the cross hole column fixes the rigid part and the flexible part without relative displacement. The present invention improves the abnormal deformation caused by the expansion and contraction of the flexible part by encapsulating one end of the flexible part in the rigid part, and connecting the single-layer flexible part and the single-layer rigid part by forming, and interposing a semi-cured sheet with low fluidity, so as to avoid the high scrap rate caused by the breakage after the stress deformation after lamination.

Description

Technical Field

[0001] The invention belongs to the technical field of rigid-flexible forming connection of copper-clad laminates, and in particular relates to a copper-clad laminate connection structure based on a thermoplastic resin base film. Background Art

[0002] Copper Clad Laminate (CCL) is a plate-like material made by impregnating electronic fiberglass cloth or other reinforcing materials with resin, covering one or both sides with copper foil and hot pressing. It is referred to as copper clad laminate. Printed circuit boards of various forms and functions are selectively processed, etched, drilled and copper-plated on copper clad laminates to make different printed circuits. It mainly plays the role of interconnection, insulation and support for printed circuit boards, and has a great influence on the transmission speed, energy loss and characteristic impedance of signals in the circuit. Therefore, the performance, quality, processability, manufacturing level, manufacturing cost, long-term reliability and stability of printed circuit boards depend to a large extent on copper clad laminates. Copper clad laminates can be divided into two categories: rigid copper clad laminates and flexible copper clad laminates.

[0003] With the development of current technology, products are increasingly pursuing small and exquisite, so the internal space left for the products will be greatly compressed. In order to adapt to the curved design of the product appearance, the circuit board placed in the product needs to use a rigid-flexible combination board to achieve maximum fitting utilization of the space.

[0004] With current technology, the size of the rigid-flexible board needs to be as thin as possible while maintaining stability. This type of problem is a difficult problem faced in production. In order to meet the design of graphics, circuits, and deformation variables during the processing and production process, as well as the alignment and positioning needs during the multi-layer composite process, it is not possible to improve its dimensional stability only by changing the processing design, processing technology, and process control of the flexible copper clad laminate. The demand for extending the life of the deformation variable must also be achieved through the connection and molding of the rigid copper clad laminate and the flexible copper clad laminate. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a copper clad laminate connection structure based on a thermoplastic resin base film, in which one end of the flexible part is covered in the rigid part, and a single-layer flexible part and a single-layer rigid part are connected by molding, and a low-fluidity semi-cured sheet is used in between to improve the abnormal deformation caused by the expansion and contraction of the flexible part, and avoid a high scrap rate caused by breaking after stress deformation after lamination.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A copper-clad laminate connection structure based on a thermoplastic resin base film comprises a rigid part, a flexible part and a connection part, wherein the rigid part comprises a glass fiber cloth, an epoxy resin layer and a rigid copper foil connected in sequence from bottom to top, a window groove is provided on the glass fiber cloth on the end edge of the rigid part, the flexible part comprises a thermoplastic resin base film and a flexible copper foil connected in sequence from bottom to top, the upper end surface of the flexible copper foil is embedded in the bottom of the window groove and abuts against the epoxy resin layer, the connection part comprises a ferry hole column and a connection plate, the connection plate is provided with a fitting section, a transition section and an abutting section, the fitting section abuts upward against the bottom of the glass fiber cloth, the abutting section abuts upward against the bottom of the thermoplastic resin base film, the cavity formed between the transition section and the thermoplastic resin base film is filled with a semi-cured sheet, the rigid part is provided with a through hole and cooperates with the ferry hole column, the ferry hole column fixes the rigid part and the flexible part without up-down, front-back and left-right relative displacement; the semi-cured sheet is composed of a mixture of epoxy resin, glass cloth and acrylic acid.

[0008] Furthermore, the fitting section is provided with a fixing hole that passes through from top to bottom, the through hole corresponds to the fixing hole, and the ferry hole column passes through the through hole and the fixing hole in sequence from top to bottom; the flexible portion is provided with a through hole that passes through from top to bottom, the through hole is located between the through hole and the fixing hole, and the ferry hole column passes through the through hole, the through hole and the fixing hole in sequence from top to bottom.

[0009] Furthermore, the ferry hole columns include several groups, and the several ferry hole columns are distributed in an equidistant array. The ratio of the distance between the ferry hole columns and one side end of the rigid part, the flexible part and the connecting part to the diameter of the ferry hole column is not less than 1:3, and the ratio of the distance between the several ferry hole columns to the diameter of the ferry hole column is in the range of 1:3 to 1:6. When it exceeds 1:6, additional ferry hole columns are provided.

[0010] Furthermore, a 45-degree oblique section and a 90-degree vertical section are provided on the side wall of the window opening groove, and the prepreg is located in a cavity enclosed by the oblique section, the vertical section, the transition section and the thermoplastic resin base film; reinforcing copper is also provided on the bottom and the oblique section of the window opening groove, and the reinforcing copper is respectively connected to the flexible copper foil and the prepreg.

[0011] Furthermore, the distance between the end of the flexible copper foil embedded in the window groove and the axial center of the hole column is not less than 0.7mm; the minimum distance between the vertical section and the outer side wall of the hole column is not less than 0.1mm; and the lateral distance of the transition section is not less than 0.75mm.

[0012] The copper clad laminate connection structure based on the thermoplastic resin base film of the structure adopted is firstly embedded in the window groove of the rigid part by embedding the flexible copper foil end of the flexible part into the window groove of the rigid part, and then respectively abutting the bottom of the rigid part and the flexible part from bottom to top through the connecting plate, and respectively opening through holes, through holes and fixing holes that are connected to each other for the rigid part, the flexible part and the connecting plate, and the cross hole column passes through them from top to bottom in sequence and is fixed by deformation pressing at the upper and lower ends, so as to ensure that there is no relative displacement between the rigid part and the flexible part up and down, front and back, left and right, and the distance between the cross hole column and one end of the rigid part, the flexible part and the connecting part is not less than 1:3 to avoid edge tearing, and the distance between a plurality of cross hole columns and the diameter of the cross hole column is in the range of 1:3 to 1:6, and the stress distance between the cross hole columns is differentiated to maintain the fastening force. When it exceeds 1:6, a cross hole column is added to maintain the relative displacement between the rigid part and the flexible part.

[0013] The abutment section on the connecting plate is laminated with the flexible part. The lamination position is located between the transition section and the abutment section. The transition section is inclined at a 45-degree angle. Since the single-piece structure of the flexible part is easily deformed, the flatness of its surface is not ideal before lamination. Moreover, the fluidity of the epoxy resin layer used is lower than that of the semi-cured sheet used for laminating the window groove of the rigid part and the flexible part. Therefore, in order to achieve a good combination of the epoxy resin layer and the single-piece flexible part, a material with good conformability is selected as the laminating gasket material, such as a mixture of epoxy resin, glass cloth and acrylic acid, which can improve the lamination quality of the flexible board, ensure its conformability and relatively reduce the shrinkage and deformation of the pressed part. Its fluidity is small. It has a great extension and deformation resistance effect on the soft-hard transition area, and will not be repeatedly reworked in the transition area due to glue overflow, or its original conductive functionality will be affected. In order to improve the ductility between the flexible part and the rigid part, reinforcing copper is provided on the bottom and oblique section of the window groove to improve flexibility. At the same time, in order to avoid the influence of the position of the reinforcing copper on the anti-relative displacement of the ferry column, the end of the flexible copper foil embedded in the window groove and the axial distance of the ferry column are not less than 0.7mm, the minimum distance between the vertical section and the outer wall of the ferry column is not less than 0.1mm, and the lateral distance of the transition section is not less than 0.75mm, which can achieve the most basic ductility and deformation resistance.

[0014] Compared with the prior art, the advantages of the present invention are: the rigid part and the flexible part are fixed by setting the cross-hole columns so that there is no relative displacement up and down, front and back, left and right, providing a basic limiting structure for the connection between the rigid part and the flexible part, and the several cross-hole columns set separately can ensure that there is no relative displacement between the rigid part and the flexible part. During the lamination process, the ductility is improved by the semi-cured sheet used for laminating the rigid part window groove and the flexible part, and reinforcing copper is also provided on the bottom and oblique section of the window groove to improve flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a cross-sectional schematic diagram of the present invention;

[0017] Figure 2 It is a cross-sectional and distance position schematic diagram of the present invention;

[0018] Figure 3 A top view of the present invention;

[0019] Figure 4 It is a test result diagram of the present invention.

[0020] Among them: 1. Rigid part; 11. Glass fiber cloth; 12. Epoxy resin layer; 13. Rigid copper foil; 14. Window groove; 141. Oblique section; 142. Vertical section; 15. Reinforced copper; 2. Flexible part; 21. Thermoplastic resin base film; 22. Flexible copper foil; 3. Connecting part; 31. Crossing column; 32. Connecting plate; 321. Laminating section; 322. Transition section; 323. Abutting section; 33. Prepreg. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0022] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings:

[0023] like Figure 1-3As shown, a copper clad laminate connection structure based on a thermoplastic resin base film comprises a rigid part 1, a flexible part 2 and a connection part 3, wherein the rigid part 1 comprises a glass fiber cloth 11, an epoxy resin layer 12 and a rigid copper foil 13 connected in sequence from bottom to top, and a window groove 14 is provided on the glass fiber cloth 11 at the end edge of the rigid part 1, and the flexible part 2 comprises a thermoplastic resin base film 21 and a flexible copper foil 22 connected in sequence from bottom to top, and the upper end surface of the flexible copper foil 22 is embedded in the bottom of the window groove 14 and abuts against the epoxy resin layer 12, and the connection part 3 comprises a ferry hole column 31 and a connection plate 32. The connecting plate 32 is provided with a fitting section 321, a transition section 322 and abutting section 323, the fitting section 321 abuts upward against the bottom of the glass fiber cloth 11, the abutting section 323 abuts upward against the bottom of the thermoplastic resin base film 21, the cavity formed between the transition section 322 and the thermoplastic resin base film 21 is filled with a semi-cured sheet 33, the rigid part 1 is provided with a through hole and cooperates with the cross hole column 31, the cross hole column 31 fixes the rigid part 1 and the flexible part 2 without relative displacement up and down, front and back, left and right; the semi-cured sheet 33 is composed of a mixture of epoxy resin, glass cloth and acrylic acid.

[0024] Furthermore, the fitting section 321 is provided with a fixing hole that passes through from top to bottom, the through hole corresponds to the fixing hole, and the ferry hole column 31 passes through the through hole and the fixing hole in sequence from top to bottom; the flexible portion 2 is provided with a through hole that passes through from top to bottom, the through hole is located between the through hole and the fixing hole, and the ferry hole column 31 passes through the through hole, the through hole and the fixing hole in sequence from top to bottom.

[0025] Furthermore, the ferry hole columns 31 include several groups, and the several ferry hole columns 31 are distributed in an equidistant array. The ratio of the distance between the ferry hole columns 31 and one side end of the rigid part 1, the flexible part 2 and the connecting part 3 to the diameter of the ferry hole column 31 is not less than 1:3, and the ratio of the distance between the several ferry hole columns 31 to the diameter of the ferry hole column 31 is in the range of 1:3 to 1:6. When it exceeds 1:6, additional ferry hole columns 31 are provided.

[0026] Furthermore, a 45-degree oblique section 141 and a 90-degree vertical section 142 are provided on the side wall of the window opening groove 14, and the prepreg 33 is located in a cavity enclosed by the oblique section 141, the vertical section 142, the transition section 322 and the thermoplastic resin base film 21; reinforcing copper 15 is also provided on the bottom of the window opening groove 14 and the oblique section 141, and the reinforcing copper 15 is respectively connected to the flexible copper foil 22 and the prepreg 33.

[0027] Furthermore, the axial distance between the end of the flexible copper foil 22 embedded in the window groove 14 and the ferry hole column 31 is not less than 0.7mm; the minimum distance between the vertical section 142 and the outer side wall of the ferry hole column 31 is not less than 0.1mm; the lateral distance of the transition section 322 is not less than 0.75mm.

[0028] Description of the working method of the present invention:

[0029] The copper clad laminate connection structure based on the thermoplastic resin base film of the structure is firstly embedded in the window groove 14 of the rigid part 1 by the end of the flexible copper foil 22 of the flexible part 2, and then the connection plate 32 is respectively abutted against the bottom of the rigid part 1 and the flexible part 2 from bottom to top, and through holes, through holes and fixing holes are respectively opened for the rigid part 1, the flexible part 2 and the connection plate 32 to communicate with each other, and the cross-hole column 31 is sequentially penetrated from top to bottom and fixed by deformation and pressing at the upper and lower ends, so as to ensure that the rigid part 1 and the flexible part 2 are connected. The rigid part 2 has no relative displacement up and down, front and back, left and right. The ratio of the distance between the cross hole column 31 and one side end of the rigid part 1, the flexible part 2 and the connecting part 3 to the diameter of the cross hole column 31 is not less than 1:3 to avoid edge tearing. The ratio of the distance between several cross hole columns 31 to the diameter of the cross hole column 31 is in the range of 1:3 to 1:6. The stress distance between the cross hole columns 31 is differentiated to maintain the fastening force. When it exceeds 1:6, additional cross hole columns 31 are provided to ensure that the rigid part 1 and the flexible part 2 remain without relative displacement under tension.

[0030] The abutment section 323 on the connecting plate 32 is laminated and pressed with the flexible part 2, and the pressing position is located between the transition section 322 and the abutment section 323. The transition section 322 is inclined at an angle of 45 degrees. Since the single-piece structure of the flexible part 2 is easily deformed, the flatness of its surface is not ideal before lamination. Moreover, the fluidity of the epoxy resin layer 12 used is lower than that of the semi-cured sheet 33 used for laminating the window groove 14 of the rigid part 1 and the flexible part 2. Therefore, in order to achieve a good combination of the epoxy resin layer 12 and the single-piece flexible part 2, a material with good conformability is selected as the laminating gasket material, such as a mixture of epoxy resin, glass cloth and acrylic acid, which can improve the lamination quality of the flexible board, ensure its conformability and relatively reduce the shrinkage deformation of the size of the pressed part. It has low fluidity and is very effective for the soft-hard transition area. It has a large extension and anti-deformation effect, and will not require repeated rework of the transition zone due to overflow of glue, or cause its original conductive functionality to be affected. In order to improve the ductility between the flexible part 2 and the rigid part 1, reinforcing copper 15 is also provided on the bottom of the window groove 14 and the oblique section 141, which can improve flexibility. At the same time, in order to avoid the position of the reinforcing copper 15 affecting the anti-relative displacement of the ferry hole column 31, the axial distance a between the end of the flexible copper foil 22 embedded in the window groove 14 and the ferry hole column 31 is not less than 0.7mm, the minimum distance b between the vertical section 142 and the outer wall of the ferry hole column 31 is not less than 0.1mm, and the lateral distance c of the transition section 322 is not less than 0.75mm, which can achieve the most basic ductility and anti-deformation effect. When it is lower than this value, the scrap rate will be greatly increased.

[0031] By clamping the tensile tester between the rigid part 1 and the flexible part 2, the sample test is carried out by generating deformation by stretching the distance to detect the tensile test under the action of external force. Figure 4The results show that the ultimate deformation capacity of the copper clad laminate connection structure based on the thermoplastic resin base film 21 of the present invention is 1.5 to 2.5 times that of the conventional laminated rigid-flex joint board. The test results are based on the reference curve integrated by the tests of several groups of test products. In the actual trial production and formal production, in the process of gradually adjusting the axial distance a between the end of the flexible copper foil 22 embedded in the window slot 14 and the cross hole column 31, the minimum distance b between the vertical section 142 and the outer wall of the cross hole column 31, and the lateral distance c of the transition section 322, the proofing in February still However, there is a scrap rate as high as 2.19%. After adjusting the data of a, b, and c, the scrap rate from March to April gradually decreased, approaching the target scrap rate of 0.6%, and achieved the target in May with an increase in products. In June, a large number of production began, and the number of sample collections increased. In July and August, the scrap rate showed a trend of gradually decreasing, indicating that the structure can effectively improve the abnormal deformation caused by the expansion and contraction of the flexible part, and avoid the high scrap rate caused by the breakage after stress deformation after lamination. The specific deformation scrap project sample-production scrap rate data are as follows:

[0032]

[0033] The beneficial effects of the present invention are as follows: the rigid part 1 and the flexible part 2 are fixed by setting the cross hole column 31 without relative displacement up and down, front and back, left and right, providing a basic limiting structure for the connection between the rigid part 1 and the flexible part 2, and the several cross hole columns 31 set separately can ensure that the rigid part 1 and the flexible part 2 have no relative displacement. During the lamination process, the ductility is improved by the semi-cured sheet 33 used for laminating the window groove 14 of the rigid part 1 and the flexible part 2. Reinforcement copper 15 is also provided on the bottom of the window groove 14 and the inclined section 141 to improve flexibility.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A copper clad laminate connection structure based on a thermoplastic resin base film, characterized in that: The invention comprises a rigid part, a flexible part and a connecting part, wherein the rigid part comprises a glass fiber cloth, an epoxy resin layer and a rigid copper foil connected in sequence from bottom to top, a window groove is arranged on the glass fiber cloth on the end edge of the rigid part, the flexible part comprises a thermoplastic resin base film and a flexible copper foil connected in sequence from bottom to top, the upper end surface of the flexible copper foil is embedded in the bottom of the window groove and abuts against the epoxy resin layer, the connecting part comprises a cross hole column and a connecting plate, a fitting section, a transition section and an abutting section are arranged on the connecting plate, the fitting section abuts upward against the bottom of the glass fiber cloth, and the abutting section abuts upward against the thermoplastic resin base film. The bottom of the resin base film, the cavity formed between the transition section and the thermoplastic resin base film is filled with a semi-cured sheet, the rigid part is provided with a through hole and cooperates with the ferry hole column, the ferry hole column fixes the rigid part and the flexible part without up and down, front and back, left and right relative displacement; the side wall of the window opening groove is provided with a 45-degree oblique section and a 90-degree vertical section, the semi-cured sheet is located in the cavity enclosed by the oblique section, the vertical section, the transition section and the thermoplastic resin base film; reinforcing copper is also provided on the bottom and the oblique section of the window opening groove, and the reinforcing copper is respectively connected to the flexible copper foil and the semi-cured sheet.

2. The copper clad laminate connection structure based on a thermoplastic resin-based film according to claim 1, characterized in that: The fitting section is provided with a fixing hole which penetrates up and down, the through hole corresponds to the fixing hole, and the crossing hole column penetrates the through hole and the fixing hole in sequence from top to bottom.

3. The copper clad laminate connection structure based on a thermoplastic resin-based film according to claim 2, characterized in that: The flexible part is provided with a through hole which penetrates up and down, the through hole is located between the through hole and the fixing hole, and the through hole column penetrates the through hole, the through hole and the fixing hole in sequence from top to bottom.

4. The copper clad laminate connection structure based on a thermoplastic resin-based film according to claim 3, characterized in that: The ferry hole columns include several groups, and the several ferry hole columns are distributed in an equidistant array. The ratio of the distance between the ferry hole columns and one side end of the rigid part, the flexible part and the connecting part to the diameter of the ferry hole column is not less than 1:

3. The ratio of the distance between the several ferry hole columns to the diameter of the ferry hole column is in the range of 1:3 to 1:

6. When the ratio exceeds 1:6, additional ferry hole columns are provided.

5. The copper clad laminate connection structure based on a thermoplastic resin-based film according to claim 3, characterized in that: The distance between the end of the flexible copper foil embedded in the window slot and the axial center of the hole column is not less than 0.7 mm.

6. The copper clad laminate connection structure based on a thermoplastic resin-based film according to claim 5, characterized in that: The minimum distance between the vertical section and the outer side wall of the cross hole column is not less than 0.1 mm.

7. The copper clad laminate connection structure based on a thermoplastic resin-based film according to claim 6, characterized in that: The lateral distance of the transition section is not less than 0.75 mm.

8. The copper clad laminate connection structure based on a thermoplastic resin-based film according to claim 7, characterized in that: The semi-cured sheet is composed of a mixture of epoxy resin, glass cloth and acrylic acid.

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