A method for making a hole-free ring back drilling

Abstract

The invention discloses a method for making a hole-free back-drilled hole, which includes the following steps in sequence: pre-process processing; drilling, copper plating: drilling to form a through hole, copper plating to form a hole copper in the through hole and thickening the copper layer of the board surface; outer layer negative film pattern production: film pasting, exposure and development, when pasting the film, the copper ring less than or equal to 3mil on one side of the through hole and the copper layer area that needs to be retained on the board surface are filmed; etching: etching away the board surface area without film pasting; film stripping; outer layer positive film pattern production: using dry film to protect the copper ring; image electroplating: thickening the hole copper and the copper layer thickness of the board surface; back drilling: removing the copper ring by back drilling to achieve the purpose of no copper ring; flash etching: cleaning the residual copper wire and dust in the hole by flash etching; resin plugging the hole, grinding the board; post-process. The invention adopts two-time pattern production, as well as back drilling and flash etching processes, which can ensure that the copper ring is removed cleanly to avoid affecting the signal transmission of the PCB board.

Description

Technical Field

[0001] The invention relates to the field of circuit boards, and in particular to a method for manufacturing hole-free ring-back drilling. Background Art

[0002] With the rapid development of the 5G communication industry, the motherboards used in servers and switches in the communication electronics industry have higher and higher requirements for signal integrity. Generally, the back drilling process is used to remove part of the hole copper and ring. Ring refers to an annular copper ring connected to the hole copper, which is set on the surface of the PCB. It is also called "hole ring" or "copper ring". The back drilling process removes unnecessary hole copper and hole ring to meet the high-frequency and high-speed performance requirements. At present, the commonly used production method in the PCB industry is to use a back drill to directly drill out the copper of the hole mouth and the hole wall. However, there will still be a part of the residual copper at the edge of the hole mouth, which affects the signal integrity and also affects the use of the client plug-in. Summary of the invention

[0003] In order to solve the problem of residual copper in the back drilling process, which affects the signal transmission of the PCB board, the present invention provides a method for making a hole-free ring back drilling.

[0004] A method for making a hole-free ring back drilling comprises the following steps in sequence:

[0005] Pre-processing;

[0006] Drilling and copper plating: drilling to form through holes, copper plating to form copper holes in the through holes and thicken the copper layer on the board surface;

[0007] Outer negative pattern production: film pasting, exposure and development. When pasting the film, the copper ring that is less than or equal to 3mil on one side of the through hole and the copper layer area that needs to be retained on the board surface will be pasted;

[0008] Etching: Etch away the board area without film;

[0009] Film stripping: remove the dry film;

[0010] Production of outer positive film graphics: Use dry film to protect the copper ring;

[0011] Image plating: thicken the copper layer of holes and board surface;

[0012] Back drilling: remove the copper ring by back drilling to achieve the purpose of no copper ring;

[0013] Flash etching: clean the remaining copper wire and dust in the hole by flash etching;

[0014] Resin plugging holes and grinding plates;

[0015] Post-process: The copper ring can be removed cleanly to avoid affecting the signal transmission of the PCB board.

[0016] Optionally, the outer layer negative film pattern is produced using a film that is 3-6 mil larger than a single side of the through hole.

[0017] Optionally, the exposure energy is 100-120 mj, and the exposure scale is controlled at 6-7 grids.

[0018] Optionally, the developing speed is 3.5 m / min, and the upper and lower pressures are both 1.5 kg / cm 2 .

[0019] Optionally, the etching speed is 2.5-3.0 m / min, and the upper and lower pressures are 1.2-1.4 kg / cm 2 .

[0020] Optionally, for the back drilling, the feed speed is 1.0-1.4 m / min, the retract speed is 1.0-1.4 m / min, and the drilling speed is 105 Krpm.

[0021] Optionally, the flash etching has an etching speed of 7.0-7.5 m / min, and after the flash etching, the stub value of the back-drilled hole is 2-12 mil.

[0022] Optionally, for the back drilling, the diameter of the drill needle is 8 mil larger than the diameter of the through hole.

[0023] Optionally, the resin plugging is performed at least twice using aluminum sheet plugging. The first plugging is performed from the upper surface of the PCB at a plugging speed of 50 mm / s, and the second plugging is performed from the lower surface of the PCB at a plugging speed of 80 mm / s. The pressure of the scraper is 7.0 kg / cm 2 .

[0024] Optionally, the plate is baked after the resin holes are plugged, and the plate is baked at 70°C, 90°C and 110°C for 30 minutes respectively, and the plate is baked again after grinding, and the plate is baked at 120°C for 30 minutes, and then baked at 150°C for 45 minutes.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a method for manufacturing a hole-free ring back-drilling, which adopts two pattern manufacturing processes: outer layer negative pattern manufacturing and outer layer positive pattern manufacturing, as well as back-drilling and flash etching processes, which can ensure that the copper ring is removed cleanly and avoid affecting the signal transmission of the PCB board; the outer layer negative pattern manufacturing retains part of the copper ring, removes part of the copper ring by etching, and finally removes all the copper rings by back-drilling; the outer layer positive pattern manufacturing protects one end of the through hole that needs to be back-drilled with a dry film, which is beneficial to saving copper materials and avoiding thickening the copper thickness of the hole that needs to be removed by back-drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a PCB board made of an outer layer negative film pattern provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to explain the technical solution of the present invention in detail, the technical solution of the embodiment of the present invention will be clearly and completely described below. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Embodiment 1:

[0029] This embodiment provides a method for making a hole-free ring back drilling, which comprises the following steps in sequence:

[0030] (1) Pre-processing: including cutting of substrate.

[0031] (2) Drilling and copper plating: Drilling forms through holes 3, and copper plating forms copper holes in the through holes and thickens the copper layer on the board surface. The number of through holes is not limited to one.

[0032] (3) Production of outer negative film graphics: film pasting, exposure and development. When pasting the film, the copper ring that is less than or equal to 3mil on one side of the through hole and the copper layer area that needs to be retained on the board surface should be pasted. Figure 1 Specifically, the dry film 1 is applied, and the copper layer area 2 on the board surface that does not need to be retained is not applied with the dry film 1.

[0033] The outer negative pattern is made with a film that is 3-6 mil larger than the single side of the through hole, ensuring that the subsequent back drilling can remove the excess copper at the through hole opening. At the same time, it prevents the exposure alignment accuracy deviation from causing uneven hole rings and affecting the electroplating area.

[0034] The exposure energy is 100-120mj, and the exposure scale is controlled at 6-7 grids. The development speed is 3.5m / min, and the upper and lower pressures are both 1.5kg / cm 2 .

[0035] (4) Etching: Etch away the board area without film.

[0036] Etching speed is 2.5-3.0m / min, upper and lower pressures are 1.2-1.4kg / cm 2 .

[0037] Etch away the copper ring outside the 3mil.

[0038] (5) Film stripping: remove the dry film.

[0039] (6) Production of outer positive film graphics: Use dry film to protect the copper ring and the substrate area of ​​the board surface.

[0040] (7) Image plating: Thicken the copper layer of the hole copper and the board surface to a preset thickness range according to actual needs.

[0041] Because one end of the through hole that needs to be back-drilled is protected by dry film, the copper ring is protected, that is, one end of the through hole that needs to be back-drilled will not be pattern-plated, and the other end of the through hole will be pattern-plated to achieve thickening of the copper thickness of some holes. This is beneficial to saving copper usage, and subsequent back drilling can easily remove the copper of some holes and all copper rings.

[0042] (8) Back drilling: The copper ring is removed by back drilling to achieve the purpose of no copper ring, that is, to achieve the purpose of no hole ring.

[0043] Back drilling, the feed speed is 1.0-1.4 m / min, the retract speed is 1.0-1.4 m / min, and the drilling speed is 105 Krpm. In some embodiments, the feed speed and the retract speed are both 1.2 m / min.

[0044] The diameter of the drill needle used in back drilling is 8mil larger than the diameter of the through hole, and the retained copper ring is completely removed. The drill needle uses the new Jinzhou double-edge single-slot SHC AUSF series drill needle, which is coated; the pad used in the back drilling process is a black phenolic pad and a special aluminum sheet for water-soluble coating. Back drilling can be performed in a jump drilling manner.

[0045] (9) Flash etching: Clean the remaining copper wire and dust in the hole through flash etching.

[0046] Flash etching, etching speed is 7.0-7.5m / min, after flash etching, the stub value of the back drill hole is 2-12mil. The copper wire and dust left after back drilling are cleaned by SES line.

[0047] (10) Resin plugging and grinding plates;

[0048] Resin plugging, using aluminum sheet plugging, at least twice plugging, the first plugging is done from the upper surface of the PCB, the plugging speed is 50mm / S, the second plugging is done from the lower surface of the PCB, the plugging speed is 80mm / S, the pressure of the scraper is 7.0kg / cm 2 .

[0049] The stub value of 2-12mil is the most reasonable control range, and simulation verification shows that it has little impact on signal transmission.

[0050] After the holes are plugged with resin, the plate is baked at 70°C, 90°C and 110°C for 30 minutes respectively. After grinding the plate, the plate is baked again at 120°C for 30 minutes and then at 150°C for 45 minutes.

[0051] The thickness of the air guide plate used for resin plugging is 3.0mm, and the ink used is Zhendong GSH-00400L ink. Check to ensure that the ink is not too full. Check the inside of the equipment before plugging and clean up the debris.

[0052] (11) Post-process: Use conventional processes in PCB manufacturing.

[0053] The invention provides a method for manufacturing a hole-free ring back-drilling hole. The method adopts two pattern manufacturing processes: outer layer negative pattern manufacturing and outer layer positive pattern manufacturing, as well as back-drilling and flash etching processes, which can ensure that the copper ring is completely removed and avoid affecting the signal transmission of a PCB board; the outer layer negative pattern manufacturing retains part of the copper ring, removes part of the copper ring by etching, and finally removes all the copper ring by back-drilling; the outer layer positive pattern manufacturing protects one end of a through hole that needs to be back-drilled with a dry film, which is beneficial to saving copper materials and avoids thickening the copper thickness of the hole that needs to be removed by back-drilling.

[0054] Example 2

[0055] The difference between this embodiment and embodiment 1 is that this embodiment provides a method for making a hole-free ring back drilling, after the hole is plugged with resin and the plate is baked, the plugging is performed, and then the plate is baked again: after baking the plate at 120°C for 30 minutes, the plate is baked at 150°C for 45 minutes.

[0056] Specifically, this embodiment includes the following steps in sequence:

[0057] (1) Pre-processing: including cutting of substrate.

[0058] (2) Drilling and copper plating: Drilling forms through holes 3, and copper plating forms copper holes in the through holes and thickens the copper layer on the board surface. The number of through holes is not limited to one.

[0059] (3) Production of outer negative film graphics: film pasting, exposure and development. When pasting the film, the copper ring that is less than or equal to 3mil on one side of the through hole and the copper layer area that needs to be retained on the board surface should be pasted. Refer to the attached Figure 1 Specifically, the dry film 1 is applied, and the copper layer area 2 on the board surface that does not need to be retained is not applied with the dry film 1.

[0060] The outer negative pattern is made with a film that is 3-6 mil larger than the single side of the through hole, ensuring that the subsequent back drilling can remove the excess copper at the through hole opening. At the same time, it prevents the exposure alignment accuracy deviation from causing uneven hole rings and affecting the electroplating area.

[0061] The exposure energy is 100-120mj, and the exposure scale is controlled at 6-7 grids. The developing speed is 3.5m / min, and the upper and lower pressures are both 1.5kg.

[0062] (4) Etching: Etch away the board area without film.

[0063] Etching speed is 2.5-3.0m / min, upper and lower pressures are 1.2-1.4kg / cm 2 .

[0064] Etch away the copper ring outside the 3mil.

[0065] (5) Film stripping: remove the dry film.

[0066] (6) Production of outer positive film graphics: Use dry film to protect the copper ring and the substrate area of ​​the board surface.

[0067] (7) Image plating: Thicken the copper layer of the hole copper and the board surface to the preset thickness range according to actual needs.

[0068] Because one end of the through hole that needs to be back-drilled is protected by a dry film, that is, one end of the through hole that needs to be back-drilled will not be pattern-plated, and the other end of the through hole will be pattern-plated to achieve thickening of the copper thickness of some holes. This is beneficial to saving copper usage, and subsequent back drilling can easily remove the copper of some holes and all copper rings.

[0069] (8) Back drilling: The copper ring is removed by back drilling to achieve the purpose of no copper ring, that is, to achieve the purpose of no hole ring.

[0070] Back drilling, the feed speed is 1.0-1.4 m / min, the retract speed is 1.0-1.4 m / min, and the drilling speed is 105 Krpm. In some embodiments, the feed speed and the retract speed are both 1.2 m / min.

[0071] The diameter of the drill needle used in back drilling is 8mil larger than the diameter of the through hole, and the retained copper ring is completely removed. The drill needle uses the new Jinzhou double-edge single-slot SHC AUSF series drill needle, which is coated; the pad used in the back drilling process is a black phenolic pad and a special aluminum sheet for water-soluble coating. Back drilling can be performed in a jump drilling manner.

[0072] (9) Flash etching: Clean the remaining copper wire and dust in the hole through flash etching.

[0073] Flash etching, etching speed is 7.0-7.5m / min, after flash etching, the stub value of the back drill hole is 2-12mil. The copper wire and dust left after back drilling are cleaned by SES line.

[0074] (10) Resin plugging and grinding plates;

[0075] Resin plugging, using aluminum sheet plugging, at least twice plugging, the first plugging is done from the upper surface of the PCB, the plugging speed is 50mm / S, the second plugging is done from the lower surface of the PCB, the plugging speed is 80mm / S, the pressure of the scraper is 7.0kg / cm 2 .

[0076] The stub value of 2-12mil is the most reasonable control range, and simulation verification shows that it has little impact on signal transmission.

[0077] After the holes are plugged with resin, the plate is baked at 70°C, 90°C and 110°C for 30 minutes respectively. After grinding the plate, the plate is baked again at 120°C for 30 minutes and then at 150°C for 45 minutes.

[0078] The thickness of the air guide plate used for resin plugging is 3.0mm, and the ink used is Zhendong GSH-00400L ink. Check to ensure that the ink is not too full. Check the inside of the equipment before plugging and clean up the debris.

[0079] (11) Post-process: Use conventional processes in PCB manufacturing.

[0080] The invention provides a method for manufacturing a hole-free ring back-drilling hole. The method adopts two pattern manufacturing processes: outer layer negative pattern manufacturing and outer layer positive pattern manufacturing, as well as back-drilling and flash etching processes, which can ensure that the copper ring is completely removed and avoid affecting the signal transmission of a PCB board; the outer layer negative pattern manufacturing retains part of the copper ring, removes part of the copper ring by etching, and finally removes all the copper ring by back-drilling; the outer layer positive pattern manufacturing protects one end of a through hole that needs to be back-drilled with a dry film, which is beneficial to saving copper materials and avoids thickening the copper thickness of the hole that needs to be removed by back-drilling.

[0081] Example 3

[0082] The difference between this embodiment and embodiment 1 is that this embodiment provides a method for making a hole-free ring back drilling. During the back drilling process, a small hole is drilled first and then a large hole is drilled. For example, if the size of the back drilling hole is 0.4 mm, a small hole of 0.2 mm is drilled first and then a large hole of 0.4 mm is drilled.

[0083] Specifically, the following steps are included in sequence:

[0084] (1) Pre-processing: including cutting of substrate.

[0085] (2) Drilling and copper plating: Drilling forms through holes 3, and copper plating forms copper holes in the through holes and thickens the copper layer on the board surface. The number of through holes is not limited to one.

[0086] (3) Production of outer negative film graphics: film pasting, exposure and development. When pasting the film, the copper ring that is less than or equal to 3mil on one side of the through hole and the copper layer area that needs to be retained on the board surface should be pasted. Figure 1 Specifically, the dry film 1 is applied, and the copper layer area 2 on the board surface that does not need to be retained is not applied with the dry film 1.

[0087] The outer negative pattern is made with a film that is 3-6 mil larger than the single side of the through hole, ensuring that the subsequent back drilling can remove the excess copper at the through hole opening. At the same time, it prevents the exposure alignment accuracy deviation from causing uneven hole rings and affecting the electroplating area.

[0088] The exposure energy is 100-120mj, and the exposure scale is controlled at 6-7 grids. The development speed is 3.5m / min, and the upper and lower pressures are both 1.5kg / cm 2 .

[0089] (4) Etching: Etch away the board area without film.

[0090] Etching speed is 2.5-3.0m / min, upper and lower pressures are 1.2-1.4kg / cm 2 .

[0091] Etch away the copper ring outside the 3mil.

[0092] (5) Film stripping: remove the dry film.

[0093] (6) Production of outer positive film graphics: Use dry film to protect the copper ring and the substrate area of ​​the board surface.

[0094] (7) Image plating: Thicken the copper layer of the hole copper and the board surface to the preset thickness range according to actual needs.

[0095] Because one end of the through hole that needs to be back-drilled is protected by a dry film, that is, one end of the through hole that needs to be back-drilled will not be pattern-plated, and the other end of the through hole will be pattern-plated to achieve thickening of the copper thickness of some holes. This is beneficial to saving copper usage, and subsequent back drilling can easily remove the copper of some holes and all copper rings.

[0096] (8) Back drilling: The copper ring is removed by back drilling to achieve the purpose of no copper ring, that is, to achieve the purpose of no hole ring.

[0097] Back drilling, the feed speed is 1.0-1.4 m / min, the retract speed is 1.0-1.4 m / min, and the drilling speed is 105 Krpm. In some embodiments, the feed speed and the retract speed are both 1.2 m / min.

[0098] The diameter of the drill needle used in back drilling is 8mil larger than the diameter of the through hole, and the retained copper ring is completely removed. The drill needle uses the new Jinzhou double-edge single-slot SHC AUSF series drill needle, which is coated; the pad used in the back drilling process is a black phenolic pad and a special aluminum sheet for water-soluble coating. Back drilling can be performed in a jump drilling manner.

[0099] (9) Flash etching: Clean the remaining copper wire and dust in the hole through flash etching.

[0100] Flash etching, etching speed is 7.0-7.5m / min, after flash etching, the stub value of the back drill hole is 2-12mil. The copper wire and dust left after back drilling are cleaned by SES line.

[0101] (10) Resin plugging and grinding plates;

[0102] Resin plugging, using aluminum sheet plugging, at least twice plugging, the first plugging is done from the upper surface of the PCB, the plugging speed is 50mm / S, the second plugging is done from the lower surface of the PCB, the plugging speed is 80mm / S, the pressure of the scraper is 7.0kg / cm 2 .

[0103] The stub value of 2-12mil is the most reasonable control range, and simulation verification shows that it has little impact on signal transmission.

[0104] After the holes are plugged with resin, the plate is baked at 70°C, 90°C and 110°C for 30 minutes respectively. After grinding the plate, the plate is baked again at 120°C for 30 minutes and then at 150°C for 45 minutes.

[0105] The thickness of the air guide plate used for resin plugging is 3.0mm, and the ink used is Zhendong GSH-00400L ink. Check to ensure that the ink is not too full. Check the inside of the equipment before plugging and clean up the debris.

[0106] (11) Post-process: Use conventional processes in PCB manufacturing.

[0107] The invention provides a method for manufacturing a hole-free ring back-drilling hole. The method adopts two pattern manufacturing processes: outer layer negative pattern manufacturing and outer layer positive pattern manufacturing, as well as back-drilling and flash etching processes, which can ensure that the copper ring is completely removed and avoid affecting the signal transmission of a PCB board; the outer layer negative pattern manufacturing retains part of the copper ring, removes part of the copper ring by etching, and finally removes all the copper ring by back-drilling; the outer layer positive pattern manufacturing protects one end of a through hole that needs to be back-drilled with a dry film, which is beneficial to saving copper materials and avoids thickening the copper thickness of the hole that needs to be removed by back-drilling.

[0108] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are 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 on the present invention.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this implementation shall be included in the protection scope of the present invention.

Claims

1. A method for making a hole-free ring back drilling, characterized in that: The following steps are included in sequence: Pre-process processing; Drilling and copper plating: drilling to form through holes, copper plating to form copper holes in the through holes and thicken the copper layer on the board surface; Outer negative pattern production: film pasting, exposure and development. When pasting the film, the copper ring that is less than or equal to 3mil on one side of the through hole and the copper layer area that needs to be retained on the board surface will be pasted; Etching: Etch away the board area without film; Film stripping: remove the dry film; Production of outer positive film graphics: Use dry film to protect the copper ring; Image plating: thicken the copper layer of holes and board surface; Back drilling: remove the copper ring by back drilling to achieve the purpose of no copper ring; Flash etching: clean the remaining copper wire and dust in the hole by flash etching; Resin plugging holes and grinding plates; Post-process.

2. The method for making a hole-free ring back drilling according to claim 1, characterized in that: The outer layer negative film pattern is produced using a film that is 3-6 mil larger than a single side of the through hole.

3. The method for making a hole-free ring back drilling according to claim 1, characterized in that: The exposure energy is 100-120 mj, and the exposure scale is controlled at 6-7 grids.

4. The method for making a hole-free ring back drilling according to claim 1, characterized in that: The developing speed is 3.5m / min, and the upper and lower pressures are both 1.5kg / cm 2 .

5. The method for making a hole-free ring back drilling according to claim 1, characterized in that: The etching speed is 2.5-3.0 m / min, and the upper and lower pressures are 1.2-1.4 kg / cm 2 .

6. The method for making a hole-free ring back drilling according to claim 1, characterized in that: The back drilling has a feed speed of 1.0-1.4 m / min, a retract speed of 1.0-1.4 m / min, and a drilling speed of 105 Krpm.

7. The method for making a hole-free ring back drilling according to claim 1, characterized in that: The flash etching has an etching speed of 7.0-7.5 m / min. After the flash etching, the stub value of the back-drilled hole is 2-12 mil.

8. The method for making a hole-free ring back drilling according to claim 1, characterized in that: The back drilling uses a drill needle with a diameter 8 mil larger than the diameter of the through hole.

9. The method for making a hole-free ring back drilling according to claim 1, characterized in that: The resin plugging hole adopts aluminum sheet plugging hole, and the plugging hole is performed at least twice. The first plugging hole is plugged from the upper surface of the PCB, and the plugging hole speed is 50mm / S. The second plugging hole is plugged from the lower surface of the PCB, and the plugging hole speed is 80mm / S. The pressure of the scraper is 7.0kg / cm 2 .

10. The method for making a hole-free ring back drilling according to claim 1, characterized in that: After the resin plugging holes, the plate is baked at 70°C, 90°C and 110°C for 30 minutes respectively. After grinding the plate, the plate is baked again at 120°C for 30 minutes and then at 150°C for 45 minutes.

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