Preparation method of circuit board with stepped structure

Abstract

The invention discloses a method for preparing a circuit board with a step structure, which belongs to the technical field of circuit boards with step structures and comprises the following steps of: manufacturing a groove-shaped outer-layer outline pattern and an alignment pattern on an inner-layer circuit board needing to be adhered with an adhesive protective gasket; the air guide groove is communicated with the groove-shaped outer-layer outline pattern and the exterior of the inner-layer circuit board, and the air guide groove is of a glue blocking structure; one side of the sticky protective gasket is marked, alignment patterns are manufactured on the unmarked side, the two alignment patterns correspond to each other in position and are the same in shape, the unmarked side of the sticky protective gasket is glued, and gluing comprises gluing at the positions corresponding to the groove-shaped outer layer outline pattern and the air guide groove; and adhering a viscous protective gasket to the inner-layer circuit board, and sequentially carrying out pressing, drilling, pattern electroplating and uncovering to obtain the stepped structure circuit board. According to the invention, through the design of the groove-shaped outer layer contour pattern and the air guide groove, after lamination is realized, bubbling and layering are avoided after process baking, and the yield is improved by more than 10%.

Description

Technical Field

[0001] The invention relates to a method for preparing a stepped structure circuit board, and belongs to the technical field of stepped structure circuit boards. Background Art

[0002] In order to meet the requirements of interface thickness, vertical power supply and terminal product space structure, the step structure of PCB (circuit board) product structure has become a common design. In the PCB product processing part, the current step processing method is to stick a sticky protective gasket on the inner step position, and then form a step pattern by opening the cover after processing. With the demand for HDI (High Density Interconnector) Build up layer (build-up) step design, the thickness space is only about 75um, which is limited by the sticky protective gasket used, and it is easy to cause delamination and blistering between the protective gasket and the board structure after pressing. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing a stepped structure circuit board to solve the delamination and blistering problem existing in the prior art.

[0004] To achieve the above objectives, the present invention is implemented by adopting the following technical solutions: The present invention provides a method for preparing a stepped structure circuit board, comprising: A groove-shaped outer contour pattern and an alignment pattern are made on the inner circuit board to which the adhesive protective gasket is to be pasted, and an air guide groove is made on the groove-shaped outer contour pattern, the air guide groove connecting the groove-shaped outer contour pattern and the outside of the inner circuit board, the air guide groove is a glue-blocking structure, and the inner pattern has been pre-made on the inner circuit board; Mark one side of the adhesive protective gasket, make an alignment pattern on the unmarked side of the adhesive protective gasket, the two alignment patterns are in corresponding positions and have the same shape, and glue is applied on the unmarked side of the adhesive protective gasket, wherein the gluing includes gluing at a position corresponding to the groove-shaped outer layer contour pattern and at a position corresponding to the air guide groove; The adhesive protective gasket is pasted to the inner layer circuit board, and pressing, drilling, electroplating patterns and opening the cover are performed in sequence to obtain a stepped structure circuit board.

[0005] Furthermore, on the inner layer circuit board, the alignment patterns are arranged at the four corners of the groove-shaped outer layer contour pattern.

[0006] Furthermore, the air guide groove includes: an air guide groove directly connecting the groove-shaped outer layer contour pattern and the outside of the inner layer circuit board, and an air guide groove indirectly connecting the groove-shaped outer layer contour pattern and the outside of the inner layer circuit board through the inner layer pattern.

[0007] Furthermore, the adhesive protection pad is made of a transparent organic material, and the glass transition temperature of the transparent organic material is greater than 250°C.

[0008] Furthermore, marking one side of the adhesive protective pad includes: making a pattern on one side of the adhesive protective pad.

[0009] Furthermore, the gluing is performed by printing.

[0010] Furthermore, the glass transition temperature of the glue exceeds 200° C., and the color glue has no residual glue after glue removal.

[0011] Furthermore, the gluing at the position corresponding to the groove-shaped outer contour pattern includes: gluing all the positions corresponding to the frame of the groove-shaped outer contour pattern, and gluing part of the positions corresponding to the inner part of the groove-shaped outer contour pattern; The partial gluing is to apply the glue into a preset pattern, and the preset pattern is one of the following three structures: a plurality of hexagons with spacing between each other, a plurality of rhombuses with spacing between each other, and an oblique structure.

[0012] Furthermore, the glue blocking structure is one of the following three structures: a plurality of hexagons with spacing between them, a plurality of rhombuses with spacing between them, and an oblique structure.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are: The present invention provides a method for preparing a stepped structure circuit board, which achieves no blistering and delamination after lamination and process baking through the design of a groove-shaped outer layer contour pattern and an air guide groove, and the yield is improved by more than 10%; the thickness of the sticky protective gasket can be reduced by controlling the thickness of the glue, so that the step area can achieve a design thickness of no more than 3 mil (the current capability is >4 mil). BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart of a method for preparing a stepped structure circuit board provided by an embodiment of the present invention; Figure 2 is a schematic diagram of the inner layer circuit board after step S1 in embodiment 2 of the present invention is completed; Figure 3 is a schematic diagram of the adhesive protective gasket after step S2.1 in Example 2 of the present invention is completed; Figure 4 is a side view of the adhesive protective gasket after step S2.2.4 in Example 2 of the present invention is completed; Figure 5 is a schematic diagram of the non-patterned side of the adhesive protective gasket after step S2.2.4 in Example 2 of the present invention is completed; Figure 6is a schematic diagram of 3D detection in Example 2 of the present invention; Figure 7 is a schematic diagram of step S2.4 in Example 2 of the present invention; Figure 8 is a schematic diagram of a circuit board after lamination in step S3 in embodiment 2 of the present invention; Fig. 9 It is a schematic diagram of the circuit board after the cover is opened in step S3 in embodiment 2 of the present invention.

[0015] In the figure: 1. groove-shaped outer layer contour pattern; 2. alignment pattern; 3. air guide groove; 4. adhesive protective gasket; 5. pattern; 6. glue; 7. glue pattern; 8. spacing; 9. cutting shape path; 10. substrate; 11. prepreg; 12. outer copper foil. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the protection scope of the present invention.

[0017] Example 1.

[0018] like Figure 1 As shown, the present invention provides a method for preparing a stepped structure circuit board, comprising: A groove-shaped outer contour pattern and an alignment pattern are made on the inner circuit board to which the adhesive protective gasket is to be pasted, and an air guide groove is made on the groove-shaped outer contour pattern, the air guide groove connecting the groove-shaped outer contour pattern and the outside of the inner circuit board, the air guide groove is a glue-blocking structure, and the inner pattern has been pre-made on the inner circuit board; Mark one side of the adhesive protective gasket, make an alignment pattern on the unmarked side of the adhesive protective gasket, the two alignment patterns are in corresponding positions and have the same shape, and glue is applied on the unmarked side of the adhesive protective gasket, wherein the gluing includes gluing at a position corresponding to the groove-shaped outer layer contour pattern and at a position corresponding to the air guide groove; The adhesive protective gasket is pasted to the inner layer circuit board, and pressing, drilling, electroplating patterns and opening the cover are performed in sequence to obtain a stepped structure circuit board.

[0019] The present invention achieves no blistering and delamination after lamination and process baking through the design of the grooved outer layer contour pattern and the air guide groove, and the yield is improved by more than 10%; the thickness of the sticky protective gasket can be reduced by controlling the thickness of the glue, so that the design thickness of the step area does not exceed 3 mil (the current capability is >4 mil).

[0020] Example 2.

[0021] The present invention provides a method for preparing a stepped structure circuit board, comprising: S1. Design and production of inner layer circuit boards.

[0022] S1.1. For the inner layer circuit board (CCL) that needs to be pasted with a sticky protective gasket, a groove-shaped outer layer contour pattern and an alignment pattern are made to paste the sticky protective gasket and confirm and determine the alignment of the paste.

[0023] S1.2. A gas guide groove is made on the structure of the groove-shaped outer contour pattern to discharge the gas generated by the decomposition of the glue on the high-temperature pressure-sensitive adhesive protective gasket.

[0024] After step S1 is completed, the inner circuit board is as follows Figure 2 As shown, the air guide groove 3 includes: an air guide groove directly connecting the groove-shaped outer layer contour pattern 1 and the outer part of the inner layer circuit board, and an air guide groove indirectly connecting the groove-shaped outer layer contour pattern 1 and the outer part of the inner layer circuit board through the inner layer pattern; Figure 2 It can be seen that the alignment pattern 2 is located at the four corners of the groove-shaped outer layer contour pattern 1, and the closer to the outside, the better.

[0025] S2. Processing of adhesive protective gasket.

[0026] S2.1. Use high temperature resistant (Tg>250 degrees, Tg is the glass transition temperature) transparent organic material as the protective gasket, the thickness can be selected according to the needs. The transparent organic material is designed with a pattern on one side, in any form, to distinguish the processing and prevent the front and back errors.

[0027] After step S2.1, the adhesive protective pad is Figure 3 As shown, a pattern 5 is made on one side of the adhesive protective pad 3 to facilitate the distinction between the front and back sides.

[0028] S2.2. Apply glue to the non-patterned side of the adhesive protective gasket by printing, and print the liquid glue onto the adhesive protective gasket according to the design pattern.

[0029] S2.2.1. For printing, the glue used should be color glue (such as black) that is resistant to high temperature (Tg>200 degrees) and high pressure and leaves no residual glue after removal. It is easy to align and it is easy to see whether there is any residue after removing the tape.

[0030] S2.2.2. Improve the glue covering method from full coverage to graphic coverage, and the graphic design structure is: glue is applied at the position corresponding to the groove-shaped outer contour graphic, including: fully glue is applied at the position corresponding to the frame of the groove-shaped outer contour graphic, and partially glue is applied at the position corresponding to the inside of the groove-shaped outer contour graphic.

[0031] Partial gluing is to apply the glue into a preset pattern, and the preset pattern is one of the following three structures: a plurality of hexagons with spacing between each other, a plurality of rhombuses with spacing between each other, and an oblique structure. The preset pattern of different proportions can be adjusted by adjusting the spacing.

[0032] The width of the grooved outer contour graphic shall not be less than 3mm.

[0033] S2.2.3. The air guide groove adopts a glue-blocking structure to prevent the glue of the semi-cured sheet (PP) from flowing into the protective gasket during the pressing process. At the same time, the gas in the protective gasket or the gas during high-temperature processing can be discharged through the air guide groove, thereby improving the defect.

[0034] The glue blocking structure includes: multiple hexagons with spacing between each other, multiple rhombuses with spacing between each other, and an oblique structure. Among them, the multiple hexagons with spacing between each other have a better glue blocking effect than the other two because the path is not a straight line. At the same time, by adjusting the spacing, the glue blocking effect changes more significantly.

[0035] S2.2.4. Design alignment patterns on the protective gasket to determine the alignment of the adhesive. Use 3D detection to quantify the alignment level.

[0036] The alignment graphics are all circular, and the alignment level can be confirmed by checking whether the centers of the two circles are aligned. Figure 6 As shown, the centers of the two alignment patterns are not aligned, so Figure 6 The alignment is shown as misaligned.

[0037] After step S2.2.4, the side of the adhesive protective pad is as follows Figure 4 As shown, one side of the sticky protective gasket 4 has a pattern 5 for distinguishing the front and back sides, and glue is applied on the side without the pattern 5. The distribution position of the glue 6 corresponds to the position of the grooved outer contour pattern 1 and the air guide groove, and the alignment pattern 2 on the sticky protective gasket 4 corresponds to the position of the alignment pattern on the inner layer circuit board.

[0038] After step S2.2.4, the non-patterned side of the adhesive protective pad is Figure 5 As shown, there is glue on the adhesive protective gasket 4 at positions corresponding to the groove-shaped outer contour pattern 1 and the air guide groove, the glue pattern 7 is a hexagon, and there is a spacing 8 between the hexagons. The position of the alignment pattern 2 on the adhesive protective gasket 4 corresponds to the position of the alignment pattern on the inner layer circuit board.

[0039] S2.2.5. The thickness of the glue can be adjusted by adjusting the mesh count of the printing screen and the printing parameters. The thickness can be controlled within 5-25um. To improve the quality, the thinner the better.

[0040] S2.3. The printed protective gasket is cured by baking.

[0041] S2.4. Cut the large protective gasket into small protective gaskets.

[0042] According to the product precision requirements, die cutting, laser forming, etc. can be used. The cutting shape path must be on the rubber surface, such as Figure 7 As shown, the cutting contour path 9 must be on the glue surface.

[0043] S3. Stick the adhesive protective gasket to the inner layer circuit board.

[0044] S4. Press, drill, electroplate and open the cover according to the normal process.

[0045] After pressing, the circuit board is as follows Figure 8 As shown, the prepreg 11 and the substrate 10 are alternately arranged, the outermost layer is the outer copper foil 12, and the positional relationship of the grooved outer contour pattern 1, the alignment pattern 2, the adhesive protective pad 4, the pattern 5 and the glue 6 has been described above and will not be repeated here.

[0046] After opening the cover, the circuit board Fig. 9 As shown, the prepregs 11 and the substrates 10 are arranged alternately, and the outermost layer is the outer copper foil 12 .

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a stepped structure circuit board, characterized in that: include: A groove-shaped outer contour pattern and an alignment pattern are made on the inner circuit board to which the adhesive protective gasket is to be pasted, and an air guide groove is made on the groove-shaped outer contour pattern, the air guide groove connecting the groove-shaped outer contour pattern and the outside of the inner circuit board, the air guide groove is a glue-blocking structure, and the inner pattern has been pre-made on the inner circuit board; Mark one side of the adhesive protective gasket, make an alignment pattern on the unmarked side of the adhesive protective gasket, the two alignment patterns are in corresponding positions and have the same shape, and glue is applied on the unmarked side of the adhesive protective gasket, wherein the gluing includes gluing at a position corresponding to the groove-shaped outer layer contour pattern and at a position corresponding to the air guide groove; The adhesive protective gasket is pasted to the inner layer circuit board, and pressing, drilling, electroplating patterns and opening the cover are performed in sequence to obtain a stepped structure circuit board.

2. The method for preparing a stepped structure circuit board according to claim 1, characterized in that: On the inner layer circuit board, the alignment pattern is set at the four corners of the groove-shaped outer layer contour pattern.

3. The method for preparing a stepped structure circuit board according to claim 1, characterized in that: The air guide grooves include: an air guide groove that directly connects the groove-shaped outer layer contour pattern and the outside of the inner layer circuit board, and an air guide groove that indirectly connects the groove-shaped outer layer contour pattern and the outside of the inner layer circuit board through the inner layer pattern.

4. The method for preparing a stepped structure circuit board according to claim 1, characterized in that: The adhesive protection pad is made of a transparent organic material, and the glass transition temperature of the transparent organic material exceeds 250°C.

5. The method for preparing a stepped structure circuit board according to claim 1, characterized in that: The marking of one side of the adhesive protective pad includes: making a pattern on one side of the adhesive protective pad.

6. The method for preparing a stepped structure circuit board according to claim 1, characterized in that: The gluing is performed by printing.

7. The method for preparing a stepped structure circuit board according to claim 1, characterized in that: The glass transition temperature of the glue is over 200° C., and the glue is a color glue with no residual glue after glue removal.

8. The method for preparing a stepped structure circuit board according to claim 1, characterized in that: The gluing at the position corresponding to the groove-shaped outer contour pattern includes: gluing all the positions corresponding to the frame of the groove-shaped outer contour pattern, and gluing part of the positions corresponding to the inner part of the groove-shaped outer contour pattern; The partial gluing is to apply the glue into a preset pattern, and the preset pattern is one of the following three structures: a plurality of hexagons with spacing between each other, a plurality of rhombuses with spacing between each other, and an oblique structure.

9. The method for preparing a stepped structure circuit board according to claim 1, characterized in that: The glue blocking structure is one of the following three structures: a plurality of hexagons with spacing between them, a plurality of rhombuses with spacing between them, and an oblique structure.

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