Manufacturing method of PCB (Printed Circuit Board) back plate

Abstract

The invention discloses a manufacturing method of a PCB (printed circuit board) backboard, which comprises the steps of drilling and copper plating of a daughter board, attaching of photosensitive polyimide and curing of the photosensitive polyimide, and comprises the following steps of: drilling a through hole in the daughter board, electroplating, depositing copper on the board surface of the daughter board and in the through hole, and printing the photosensitive polyimide on one side of the daughter board to cover one end of the through hole; and the photosensitive polyimide is cured through a curing process, so that the reliability of a final product can be greatly improved, and the risk of plate explosion in the process of welding a device on the back plate is completely eradicated.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a PCB backplane, and belongs to the technical field of PCB board manufacturing. Background Art

[0002] The existing scheme for making mechanical crimping holes on high-speed backplanes is to drill through holes and etch hole rings on the two pressed daughter boards in advance. At the same time, to prevent the resin on the resin sheet from flowing and blocking the crimping holes during hot pressing, a hole slightly larger than the through hole of the daughter board is drilled on the low-fluidity resin sheet, and then the two daughter boards are pressed together using the drilled low-fluidity resin sheet through a hot press. The resin sheet on the outer layer of the daughter board is also pressed with copper foil using the drilled low-fluidity resin sheet, and finally the copper foil at the outer crimping hole position is torn off for use in plugging in high-speed backplane adapters.

[0003] However, due to the low fluidity of the resin sheet between the layers of the PCB board, the inner layer of the PCB board will cause the crimping holes to become void. When encountering a backplane that requires welding, the board will explode, posing a huge reliability risk. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for manufacturing a PCB backplane, aiming to improve the reliability of the PCB backplane and reduce the risk of backplane explosion during the process of backplane welding components.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions: The present invention provides a method for manufacturing a PCB backplane, comprising the following steps: After drilling through holes on the daughter board, electroplating is performed to deposit copper on the daughter board surface and in the through holes; printing photosensitive polyimide on one side of the daughter board to cover one end of the through hole to form a crimping hole; The photosensitive polyimide is cured through a curing process.

[0006] Furthermore, before photosensitive polyimide is offset-printed on the bottom of the through hole to cover one end of the through hole, a preset pattern is made on the daughter board by using a pattern transfer method.

[0007] Furthermore, the sub-board is manufactured by: pressing the inner layer boards with patterns made thereon together using resin sheets by hot pressing to form the sub-board.

[0008] Furthermore, the curing process includes: The photosensitive polyimide is pre-cured by exposure using an exposure machine and then cured in an oven.

[0009] Furthermore, the curing conditions in the oven are: a temperature of 150 degrees Celsius and a time of 2 hours.

[0010] Further, after curing the photosensitive polyimide by a curing process, it further includes: processing of the sub-outer resin sheet: using a numerically controlled drilling machine to drill a through-hole larger than the diameter of the press-fit hole at the position corresponding to the press-fit hole on the sub-outer resin sheet.

[0011] Further, the method for manufacturing the PCB backplane further includes: Cover the drilled sub-outer resin sheet on the other side of the daughter board, then cover the copper foil on the sub-outer resin sheet, and finally use a hot press to press the daughter board, the sub-outer resin sheet, and the copper foil together. At this time, the copper foil covers the other end of the press-fit hole.

[0012] Further, the method for manufacturing the PCB backplane further includes: after manufacturing the outer layer pattern, tear off the copper foil at the position of the press-fit hole to expose the other end of the press-fit hole, forming a press-fit blind hole.

[0013] Further, the method for manufacturing the PCB backplane further includes: attaching one side of the two daughter boards and pressing the two daughter boards together, and at the same time, arranging an inner resin sheet between the two daughter boards as an insulating layer.

[0014] Further, the through-hole drilled in the sub-outer resin sheet by the numerically controlled drilling machine is 10 mil larger than the diameter of the press-fit hole.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention provides a method for manufacturing a PCB backplane. Using a photosensitive polyimide with high viscosity and strong binding force with resin to seal the position of the interlayer press-fit hole can provide more reliable structural performance for the end of the press-fit hole, and at the same time improve the overall structural stability of the PCB backplane. The manufacturing method provided by the present invention greatly improves the reliability of the product and effectively eliminates the risk of the PCB backplane bursting during the process of welding components. Description of the Drawings

[0016] Figure 1 is a schematic exploded view of the structure of a PCB backplane in the prior art; Figure 2 is an exploded view of a PCB backplane in the prior art; Figure 3 is a schematic exploded view of the structure of a PCB backplane provided by an embodiment of the present application; Figure 4 is a schematic diagram of the structure of a PCB backplane provided by an embodiment of the present application; Figure 5 is a schematic flow chart of the method for manufacturing a PCB backplane provided by an embodiment of the present invention; In the figure: 1, daughter board; 2, press-fit hole; 3, photosensitive polyimide; 4, sub-outer resin sheet, 5, copper foil; 6, inner resin sheet. Detailed implementation mode

[0017] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and cannot be used to limit the protection scope of the present invention.

[0018] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0019] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations. Embodiment

[0020] Compared with the existing PCB backplane (such as Figure 1 , Figure 2 shown), please refer to Figure 3 , Figure 4 and Figure 5 , this embodiment introduces a manufacturing method of a PCB backplane, including the following steps: S1. Inner layer board manufacturing: Cut the copper clad laminate into the required size, and according to the graphic design, use the method of exposure, development and etching to make graphics on the copper clad laminate to obtain the inner layer board.

[0021] S2. By means of hot pressing, press the inner layer boards with made graphics together with resin sheets to form sub-board 1.

[0022] S3. Drill through holes on sub-board 1 and then electroplate to deposit copper on the board surface and through holes of sub-board 1.

[0023] S4. Use a pattern transfer method to fabricate a preset pattern on the daughter board 1.

[0024] S5. Print photosensitive polyimide 3 (PSPI) on one side of the daughter board 1 to cover one end of the via hole, forming a press-fit hole 2.

[0025] S6. Cure the photosensitive polyimide 3 through a curing process.

[0026] In this embodiment, the curing process includes: irradiating with an exposure machine to pre-cure the photosensitive polyimide 3, and then curing it in an oven.

[0027] Among them, the conditions for curing in the oven are: the temperature is 150 degrees Celsius and the time is 2 hours.

[0028] S7. Processing of the second outer resin sheet 4: Use a numerical control drilling machine to drill a through hole larger than the diameter of the press-fit hole 1 at the position corresponding to the press-fit hole on the second outer resin sheet 4.

[0029] Among them, the through hole drilled in the second outer resin sheet 4 using the numerical control drilling machine is 10 mil larger than the diameter of the press-fit hole 2.

[0030] S8. Outer layer manufacturing: Cover the drilled second outer resin sheet 4 on the other side of the daughter board 1, then cover the copper foil 5 on the second outer resin sheet 4, and finally use a hot press to press the daughter board 1, the second outer resin sheet 4, and the copper foil 5 together. At this time, the copper foil 5 covers the other end of the press-fit hole 2.

[0031] It should be added that the second outer resin sheet 4 is a low-fluidity resin sheet. In this embodiment, the resin fluidity of the low-fluidity resin sheet is 1% - 5%.

[0032] S9. Exposing the press-fit blind hole: After the outer layer pattern is fabricated, tear off the copper foil 5 at the position of the press-fit hole 2 to expose the other end of the press-fit hole 2, forming a press-fit blind hole.

[0033] For the PCB backplane fabricated by the method of the present invention, the press-fit hole 2 is sealed by the photosensitive polyimide 3 through printing. The photosensitive polyimide 3 can improve the structural strength at the end of the press-fit blind hole, thereby greatly improving the reliability of the product, eliminating the risk of board explosion during the process of soldering components on the backplane, and reducing production costs. Embodiment

[0034] As Figure 4 shown, this embodiment provides a PCB backplane, which is fabricated by using the manufacturing method of a PCB backplane provided in Embodiment 1.

[0035] The PCB backplane is formed by laminating two sub-boards 1, and one end of the press-fit hole 2 is open to the outside, while the other end is covered with photosensitive polyimide 3, so that the press-fit hole 2 forms a blind hole. The outer surface of the sub-board 1 is covered with copper foil 5. Among them, when hot-pressing the two sub-boards 1 with a hot press, one side of the two sub-boards 1 can be adhered and the two sub-boards 1 can be laminated, and at the same time, an inner resin sheet 6 is arranged between the two sub-boards 1 as an insulating layer.

[0036] It should be added that the above-mentioned inner resin sheet 6 is a resin sheet with high conventional fluidity. In this embodiment, the fluidity of the resin with high conventional fluidity is 15%-20%.

[0037] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present disclosure rather than limit the scope of its protection. Although the present disclosure has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: after reading the present disclosure, those skilled in the art can still make various changes, modifications or equivalent replacements to the specific implementation manners of the invention, but these changes, modifications or equivalent replacements are all within the scope of protection of the claims pending for publication.

Claims

1. A method for manufacturing a PCB backplane, characterized in that: The following steps are involved: After drilling through holes on the daughter board, electroplating is performed to deposit copper on the daughter board surface and in the through holes; printing photosensitive polyimide on one side of the daughter board to cover one end of the through hole to form a crimping hole; The photosensitive polyimide is cured through a curing process.

2. The method for manufacturing a PCB backplane according to claim 1, characterized in that: Before photosensitive polyimide is offset printed on the bottom of the through-hole to cover one end of the through-hole, a predetermined pattern is made on the daughter board using a pattern transfer method.

3. The method for manufacturing a PCB backplane according to claim 1, characterized in that: The sub-board is manufactured by pressing the inner-layer boards with patterns made thereon together using resin sheets by hot pressing to form the sub-board.

4. The method for manufacturing a PCB backplane according to claim 1, characterized in that: The curing process includes: The photosensitive polyimide is pre-cured by exposure using an exposure machine and then cured in an oven.

5. The method for manufacturing a PCB backplane according to claim 4, characterized in that: The curing conditions in the oven are: temperature 150 degrees Celsius, time 2 hours.

6. The method for manufacturing a PCB backplane according to claim 1, characterized in that: After curing the photosensitive polyimide through a curing process, the method further includes: processing the secondary outer layer resin sheet: using a CNC drill to drill a through hole larger than the diameter of the crimping hole at the position of the corresponding crimping hole of the secondary outer layer resin sheet.

7. The method for manufacturing a PCB backplane according to claim 6, characterized in that: The method for manufacturing the PCB backplane further includes: Cover the drilled secondary outer resin sheet on the other side of the daughter board, then cover the copper foil on the secondary outer resin sheet, and finally use a hot press to press the daughter board, secondary outer resin sheet and copper foil together, at this time the copper foil covers the other end of the crimping hole.

8. The method for manufacturing a PCB backplane according to claim 7, characterized in that: The manufacturing method of the PCB backplane also includes: after the outer layer pattern is manufactured, the copper foil at the position of the crimping hole is torn off to expose the other end of the crimping hole to form a crimping blind hole.

9. The method for manufacturing a PCB backplane according to claim 6, characterized in that: The manufacturing method of the PCB backplane also includes: attaching one side of the two sub-boards to each other and pressing the two sub-boards together, and at the same time arranging an inner layer resin sheet between the two sub-boards as an insulating layer.

10. The method for manufacturing a PCB backplane according to claim 6, characterized in that: The through hole drilled in the second outer layer resin sheet by using a CNC drill is 10 mil larger than the diameter of the crimping hole.

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