A method for manufacturing FR4 and PTFE mixed pressure circuit board

Abstract

The application discloses a manufacturing method of FR4 and PTFE mixed voltage circuit board, comprising the following steps: cutting, baking, inner layer dry film, inner layer AOI, pressing, mechanical drilling, plasma glue removal, copper deposition, pulse electroplating, single-side copper reduction, outer layer circuit, outer layer etching, outer layer AOI, solder mask, post-process, between the plasma glue removal and the copper deposition, there is a baking plate process for eliminating stress in the circuit board blank and eliminating moisture in the PTFE material again, between the outer layer AOI and the solder mask, there is a UV machine process for further eliminating moisture in the PTFE material and making the resin material shrink.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a FR4 and PTFE mixed-pressure circuit board. Background Technology

[0002] Currently, the substrate and prepreg in circuit boards are generally made of FR4 epoxy resin. However, when manufacturing high-precision radar circuit boards, the relatively high DK and DF values ​​of FR4 can significantly affect signal transmission. Therefore, the industry has developed hybrid circuit boards that use both FR4 and PTFE materials as substrates and prepregs in the same circuit board. PTFE material has low DK and low DF values, providing strong protection for signal transmission and greatly reducing its impact on signal transmission. However, PTFE material is highly susceptible to environmental influences, absorbing moisture from the air and becoming damp. For example, the high-frequency board manufacturing method disclosed in Chinese invention patent CN110012620B cannot effectively eliminate moisture from the PTFE material in hybrid circuit boards. This leads to a decrease in the bonding strength between the substrate / prepreg and the copper, and also affects the dimensional stability of the circuit board.

[0003] Therefore, overcoming the aforementioned shortcomings has become an important issue that urgently needs to be addressed by those skilled in the art. Summary of the Invention

[0004] This invention overcomes the shortcomings of the above-mentioned technologies and provides a method for manufacturing a FR4 and PTFE mixed-pressure circuit board.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for manufacturing an FR4 and PTFE mixed-pressure circuit board includes the following steps: blanking, baking, inner layer dry film, inner layer AOI, lamination, mechanical drilling, plasma desmearing, copper plating, pulse electroplating, single-sided copper reduction, outer layer circuitry, outer layer etching, outer layer AOI, solder mask, and post-processing. Between plasma desmearing and copper plating, there is a baking process to eliminate stress in the circuit board blank and to further remove moisture from the PTFE material. Between outer layer AOI and solder mask, there is a UV coating process to further remove moisture from the PTFE material and to cause the resin material to shrink.

[0007] Preferably, the PTFE sheet is sandwiched between two clean, bare plates during handling from the time of cutting to the time of pressing.

[0008] Preferably, an additional step is added for both inner and outer AOI: a polarizing filter is installed on the camera of the detection device for detection.

[0009] Preferably, reverse copper foil or high-temperature resistant release film is used as a buffer material when arranging the plates during the lamination process.

[0010] Preferably, the lifespan of the drill bit is controlled at 500 hits during mechanical drilling, and the circuit board blank is cleaned three times with high-pressure water washing and ultrasonic water washing after drilling.

[0011] An FR4 and PTFE hybrid circuit board is manufactured using the aforementioned method for manufacturing FR4 and PTFE hybrid circuit boards.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] The manufacturing method in this case adds a baking process between the plasma desmearing and copper plating processes. Baking effectively removes moisture from the PTFE material and reduces stress within the circuit board blank, thereby enhancing the bonding between the board, prepreg, and copper. In addition, this manufacturing method adds a UV process between the outer AOI and solder mask processes. By placing the circuit board blank in the UV machine for irradiation, the resin material shrinks, which further eliminates the deformation of the circuit board blank caused by PTFE absorbing moisture from the air and becoming damp, thus increasing the dimensional stability of the circuit board after it leaves the factory. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of an FR4 and PTFE mixed-pressed circuit board manufactured using the manufacturing method of the FR4 and PTFE mixed-pressed circuit board in this case, wherein 1 is a copper layer, 2 is an FR4 material board, 3 is an FR4 prepreg, and 4 is a PTFE board. Detailed Implementation

[0015] The following examples further illustrate the features and other related characteristics of the present invention in detail, to facilitate understanding by those skilled in the art:

[0016] A method for manufacturing a hybrid FR4 and PTFE circuit board includes the following steps:

[0017] Material cutting: Cutting materials according to the design dimensions to obtain FR4 substrate core board, FR4 prepreg, PTFE substrate core board, and PTFE prepreg of corresponding dimensions;

[0018] Baking: Baking the FR4 substrate core board and PTFE substrate core board eliminates stress in the core board and removes moisture;

[0019] Inner layer dry film: The inner layer circuitry is created by transferring patterns from the inner core board.

[0020] Inner layer AOI: Identifies defects in the inner layer core board circuitry through optical inspection;

[0021] Pressing: According to the circuit board design sequence, FR4 substrate core board and PTFE substrate core board are stacked together, and FR4 semi-cured sheet or PTFE semi-cured sheet is placed between the two core boards as an adhesive according to the circuit board design requirements. Then, the stacked core boards and semi-cured sheets are pressed together by a presser to obtain the circuit board blank.

[0022] Mechanical drilling: Drilling holes in the circuit board blank according to the circuit board design requirements;

[0023] Plasma desmearing: Plasma treatment is used to remove drilling debris from the holes of circuit board blanks;

[0024] Baking plate: Baking the circuit board blanks eliminates stress in the circuit board blanks and removes moisture from the PTFE material once again;

[0025] Immersion copper: Chemical copper plating is performed on the holes in the circuit board blank, depositing a layer of chemical copper on the hole wall as an electroplating base;

[0026] Pulse electroplating: Increases the copper thickness inside the holes on the circuit board blank to ensure reliable connection between the layers of the circuit board;

[0027] Single-sided copper reduction: Correcting the copper thickness by reducing copper on one side;

[0028] Outer layer circuitry: Pattern transfer is performed on the outer layer of the circuit board blank;

[0029] Outer layer etching: etching the outer layer circuitry onto the outer layer of the circuit board blank;

[0030] Outer layer AOI: Identifies defects in the outer layer circuitry of a circuit board through optical inspection;

[0031] UV treatment: The circuit board blank is placed in a UV machine for irradiation treatment to further remove moisture from the PTFE material and at the same time cause the resin material to shrink.

[0032] Solder resist: A solder resist layer is created on the surface of a circuit board blank;

[0033] Subsequent processes: CNC machining is performed on the circuit board blanks to separate the circuit board products, and the functionality of the circuit board products is tested through point testing.

[0034] As described above, the manufacturing method of this case adds a baking process between the plasma desmearing and copper plating processes. The baking process can effectively remove moisture from the PTFE material and also eliminate stress in the circuit board blank, reducing deformation and thus enhancing the bonding between the board and the prepreg and the copper. In addition, this manufacturing method also adds a UV process between the outer AOI and solder resist processes. By placing the circuit board blank in the UV machine for irradiation treatment, the resin material shrinks, which can further eliminate the deformation of the circuit board blank caused by the PTFE absorbing moisture from the air and becoming damp, thereby increasing the dimensional stability of the circuit board after it leaves the factory.

[0035] Preferably, from the time of cutting to the time of pressing, the PTFE material sheet is sandwiched between two clean, smooth plates during handling. In this way, the PTFE sheet can be protected by the smooth plates during handling, thereby overcoming the problems of dents, deformation, and damage caused by the softness and easy deformation of the PTFE sheet itself.

[0036] Preferably, an additional step is added to both the inner and outer AOI processes: a polarizing filter is installed on the camera of the inspection equipment for inspection. This avoids the problem of unclear AOI light reflection caused by the gray substrate of the PTFE material, thereby improving the AOI quality.

[0037] Preferably, reverse copper foil or high-temperature resistant release film is used as a buffer material during the lamination process. In this way, the PTFE material sheets can be better protected by using reverse copper foil or high-temperature resistant release film instead of conventional kraft paper as the buffer material for lamination.

[0038] Preferably, the drill bit life is controlled at 500 hits during mechanical drilling. After drilling, the circuit board blank is cleaned three times with high-pressure water washing and ultrasonic water washing. In this way, by controlling the drill bit life and maintaining the drill bit performance, rough hole walls are avoided. Combined with high-pressure water washing and ultrasonic water washing to remove cutting chips, the drilling quality can be guaranteed and the copper plating effect can be improved. At the same time, it can avoid damage to the PTFE material caused by using mechanical grinding plates to polish the hole opening.

[0039] like Figure 1 As shown, an FR4 and PTFE hybrid circuit board is manufactured using the aforementioned method for manufacturing FR4 and PTFE hybrid circuit boards.

[0040] As stated above, this case protects a method for manufacturing a FR4 and PTFE hybrid circuit board, and all technical solutions that are the same as or similar to this case should be considered to fall within the scope of protection of this case.

Claims

1. A method for manufacturing a FR4 and PTFE mixed-pressure circuit board, comprising the following steps: material preparation, baking, inner layer dry film, inner layer AOI, lamination, mechanical drilling, plasma desmearing, copper plating, pulse electroplating, single-sided copper reduction, outer layer circuitry, outer layer etching, outer layer AOI, solder mask, and post-processing, characterized in that... Between plasma descaling and copper plating, there is a baking process to eliminate stress in the circuit board blank and remove moisture from the PTFE material again. Between the outer AOI and solder mask, there is a UV process to further remove moisture from the PTFE material and shrink the resin material.

2. The method for manufacturing an FR4 and PTFE mixed-pressure circuit board according to claim 1, characterized in that... From the time of cutting to the time of pressing, the PTFE sheet is carried between two clean, bare plates.

3. The method for manufacturing an FR4 and PTFE hybrid laminated circuit board according to claim 1, characterized in that... An additional step is added to both the inner and outer AOI processes: a polarizing filter is installed on the camera of the inspection equipment for inspection.

4. The method for manufacturing an FR4 and PTFE mixed-pressure circuit board according to claim 1, characterized in that... Reverse copper foil or high-temperature release film are used as buffer materials during the lamination process.

5. The method for manufacturing an FR4 and PTFE mixed-pressure circuit board according to claim 1, characterized in that... During mechanical drilling, the drill bit life is controlled at 500 hits. After drilling, the circuit board blank is cleaned three times with high-pressure water washing and ultrasonic water washing.

6. A hybrid FR4 and PTFE circuit board, characterized in that... It is manufactured using the method described in any one of claims 1-5 for manufacturing FR4 and PTFE mixed-pressure circuit boards.

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