Processing technology for metalized half hole of thick copper circuit board

Abstract

The invention relates to a thick copper circuit board metallization half hole processing technology comprising the following steps: drilling holes on a laminated circuit board to prepare for subsequent PTH half holes; performing negative film drying after electroplating copper on the circuit board; copper and tin plating is carried out on the inner wall of the ultra-short slotted hole; a CNC machine tool is used for machining the metal hole, and a half hole is milled and fished out; stripping the film of the circuit board of which the half hole is fished out, and then carrying out rapid alkaline etching treatment; half-hole tin-plating dry film: pressing the tin-plating dry film on the circuit board in vacuum, and forming a window at the half-hole position; the circuit board is tinned through a pattern electroplating line, and an alkali etching resistant tin layer is plated on the exposed hole wall copper of the half hole; and carrying out film removal, etching and tin stripping treatment on the circuit board to obtain the circuit board with the half hole. The processing technology can effectively solve the problem of excessive hole wall etching caused by too slow copper thickness etching line, and can ensure that the hole wall area of the etched PTH half hole finished product is more than 90% larger than the hole wall area of the original half hole.

Description

Technical Field

[0001] This application relates to circuit board processing technology, specifically to a metallization half-hole processing technology for thick copper circuit boards. Background Technology

[0002] Plated Through-Hole Half-hole (PTH) is a special process in printed circuit boards (PCBs). PTH uses a metallized semi-circular hole structure to replace traditional connectors, achieving a compact electrical connection between different PCBs. This design retains half of the metallized hole wall after the hole is cut, forming a solderable conductive channel, significantly saving space and improving circuit transmission reliability.

[0003] With the increasing power of industrial control equipment, there is a growing demand for thick copper (copper thickness > 105μm) circuit boards to be equipped with half-hole processing technology. This has led to a new problem: over-etching of the half-hole walls in thick copper circuit boards. In the half-hole processing of thick copper boards, due to the slow etching line speed and long etching reaction time, and because the half-hole is retrieved from a long retrieval tank, the etching solution is affected by gravity and flows rapidly downward through the tank, i.e., the etching via effect. This makes the flow rate of the etching solution faster and the activity of the etching solution stronger. As a result, the sidewalls are severely etched without solder protection, resulting in an excessively small arc-shaped area of ​​the residual copper inner wall of the half-hole, which affects the conductivity and the reliability of SMT soldering. Summary of the Invention

[0004] To overcome the above-mentioned defects, this application provides a metallization half-hole processing technology for thick copper circuit boards. This processing technology can effectively solve the problem of excessive etching of the hole wall caused by the slow etching of thick copper lines, and can ensure that the finished hole wall area of ​​the PTH half-hole after etching is more than 90% larger than the original half-hole hole wall area.

[0005] The technical solution adopted by this application to solve its technical problem is:

[0006] A process for metallizing half-holes in thick copper circuit boards includes the following steps:

[0007] Drilling: Drilling holes on the laminated circuit board to prepare for subsequent PTH half-holes, wherein the holes are extremely short slots with an aspect ratio of less than 1.3.

[0008] Negative dry film: After electroplating copper on the circuit board, negative dry film is applied. For extremely short slot holes, the compensation amount of dry film coverage is greater than 0.2mm.

[0009] Pattern plating: Copper and tin plating are performed on the inner walls of extremely short slots to form metal holes;

[0010] CNC: Using CNC machine tools to machine metal holes, milling out half of the hole;

[0011] Alkaline flash etching: After the circuit board with half holes is stripped, it is subjected to rapid alkaline etching, but the tin stripping section is not removed.

[0012] Half-hole tin-plated dry film: A tin-plated dry film is vacuum-pressed onto the circuit board and exposed and developed by LDI free expansion and contraction exposure to form an opening at the half-hole position;

[0013] Half-hole tin plating: The circuit board is tin-plated through patterned electroplating lines to plate a layer of alkali-resistant tin on the exposed copper wall of the half-hole. The thickness of the tin layer is >0.35mil.

[0014] SES: The circuit board is subjected to film removal, etching and tin stripping to obtain a circuit board with half-holes.

[0015] Optionally, in the drilling process, the specifications of the drilling tool for the ultra-short slot are: drilling tool diameter 0.5±0.05mm, tool type 125RA ultra-short slot tool, and cutting length 8.7±0.5mm.

[0016] Optionally, in the drilling process, the machining parameters for ultra-short slots include: rotational speed 85±5krpm, feed rate 0.5±0.05m / min, retraction rate 18±2m / min, and a lifespan of 700 holes.

[0017] Optionally, in the negative dry film process, the dry film is a copper plating resistant dry film of model HT115F with a thickness of 1.5±0.2mil.

[0018] Optionally, during pattern electroplating, the tin plating parameters are: current 10-12A / SF, time 10-15min, and tin plating thickness 0.35-0.6mil.

[0019] Optionally, the CNC machining includes a roughing process and a finishing process. The parameters for the roughing process are: groove width 1.8±0.2mm, cutter diameter 1.4±0.2mm, spindle speed 28±2Kr / min, feed rate 3±0.5mm / s, approach speed 7±4mm / s, retraction speed 415±20mm / s, and cutter life 1±0.1m. The parameters for the finishing process are: groove width 1.8±0.2mm, cutter diameter 1.0±0.2mm, spindle speed 28±2Kr / min, feed rate 6±0.5mm / s, approach speed 7±4mm / s, retraction speed 415±20mm / s, and cutter life 2.5±0.2m.

[0020] Optionally, in the alkaline flash etching process, the conveying speed of the etching line is 6-7 m / min, the etching depth is controlled at 0.8-1.2 mil, and the parameters of the etching solution in the etching tank are: density 1.21±0.01, pH 8.35±0.25, Cu 2+ The concentration was 145±10 g / L, Cl- The concentration was 195±15 g / L and the etching rate was 3±0.5 mil / min.

[0021] Optionally, in the process of semi-hole tin plating dry film, the vacuum lamination conditions are: dry film type HT115F, thickness 1.5mil, pressure 7kg / cm. 2 Speed ​​12m / min, vacuum degree <1kpa; vacuum lamination temperature 50-60℃, LDI exposure energy 400mj, energy grid 9-10 grids; dry film development conditions: linear speed 1.8±0.2m / min; temperature 29±1.4℃.

[0022] Optionally, in the half-hole tin plating process, the tin plating parameters are: current 6-8A / SF, time 8-10min. In the tin plating process, each circuit board is spaced apart by a plating plate of the same length and 20-30cm in width.

[0023] Optionally, in the SES process, the stripping speed is controlled at 1.5m ± 0.2m / min, and the parameters of the etching solution in the etching tank are: density 1.21 ± 0.01, pH 8.35 ± 0.25, Cu 2+ 145±10g / L, Cl - The parameters of the tin stripping solution in the tin stripping bath are: density 1.21±0.01 and acidity 5±1.5N, with an etching rate of 3±0.5mil / min and a tin stripping rate of 195±10g / L.

[0024] The beneficial effects of this application are:

[0025] (1) This application can effectively solve the problem of excessive etching of the hole wall due to the slow etching of thick copper lines, and can ensure that the finished hole wall area of ​​the PTH half hole after etching is more than 90% larger than the original half hole wall area. In addition, this application uses existing equipment and chemical system of conventional PCB process, which will not increase the additional equipment cost.

[0026] (2) Through this processing technology, the integrity of the etched hole wall in the PTH half-hole processing of copper circuit boards thicker than 3oz is improved. The copper retention rate of the hole wall in the traditional PTH half-hole process is less than 40%, while this processing technology increases the copper retention rate of the hole wall to more than 90%. Through tin plating protection, the etching uniformity is improved, and it is no longer necessary to take into account the etch amount of the half-hole wall. The etching spray pressure can be flexibly adjusted to meet the requirements of the circuit etching quality. The product reliability is improved. Since the half-hole wall area retention rate is more than 90%, the instantaneous high current carrying capacity can be improved by more than 30%. The welding reliability is improved. The complete hole wall tin climbing area is large enough, and the tin climbing height can be increased to more than 75% of the board thickness. Detailed Implementation

[0027] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the embodiments described in this application are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0028] A process for metallizing half-holes in thick copper circuit boards includes the following steps:

[0029] Drilling: Drill holes on the laminated circuit board to prepare for subsequent PTH half-holes. The holes are ultra-short slots with an aspect ratio of less than 1.3. The thickness of the inner substrate copper foil of the circuit board is about 4 oz, and the thickness of the outer laminated copper foil is about 3 oz. Optionally, by setting the holes as ultra-short slots, the length of the half-hole can be extended by 0.1-0.2 mm, thereby allowing for an offset of 0.1-0.15 mm for CNC cutting of the half-hole, and avoiding the reduction of the inner wall area of ​​the hole due to the offset.

[0030] Negative dry film: After electroplating copper on the circuit board, a negative dry film is applied. For extremely short slots, the compensation amount of the dry film coverage is greater than 0.2mm. This ensures that the diameter of the formed hole ring is at least 0.2mm larger than the diameter of the half-hole. In other words, the dry film protects the area around the half-hole, ensuring that only the target area is processed during subsequent etching or electroplating. The window is extended by at least 9mil outside the half-hole solder ring, where 1mil equals 25.4μm. That is, the dry film window size is about 0.2mm larger than the hole, allowing the solder to fully cover the hole during soldering. This design is mainly to enhance soldering reliability and ensure that the hole ring can still maintain a sufficient solder hole ring even under the superposition of etching solution through-hole effects.

[0031] Pattern electroplating: Copper and tin plating are performed on the inner wall of the extremely short slot to form a metal hole; the copper plating thickness is about 17.8μm, and the electroplating parameters are calculated based on the plating area.

[0032] CNC: Using CNC machine tools to machine metal holes, milling out half of the hole;

[0033] Alkaline flash etching: After the circuit board with half-holes is stripped, it is subjected to rapid alkaline etching, but without going through the tin stripping section; the dry film is stripped, and the exposed copper wires at the half-hole position are quickly etched away by alkaline flash etching, but without going through the tin stripping section.

[0034] Half-hole tin-plated dry film: A tin-plated dry film is vacuum-pressed onto the circuit board and exposed and developed by LDI free expansion and contraction exposure to form an opening at the half-hole position;

[0035] Half-hole tin plating: The circuit board is tin-plated using patterned electroplating lines, depositing an alkaline-etch-resistant tin layer onto the exposed copper walls of the half-holes. The thickness of the tin layer is >0.35mil. This ensures the integrity of the copper on the hole walls and effectively controls the etching depth of the copper back through the holes, which can be controlled within 0.8mil. It also ensures that the area retention rate of the hole walls is greater than 90% of the original half-hole wall area.

[0036] SES: StripInk stripping, etching, and stripping of solder on a circuit board to obtain a circuit board with half-holes. SES consists of StripInk stripping, Etch etching, and Strip again solder stripping.

[0037] In this application, during the drilling process, the PTH metallized round hole is pre-processed into an extremely short slot to lengthen the hole wall and reserve an offset of 0.1-0.15mm for CNC cutting. For the hole wall ring attached to the outer layer of the half-hole, the compensation amount of the dry film coverage needs to be >9mil to ensure that the hole ring can still maintain sufficient soldering hole ring under the superposition of etching solution through-hole effect. After the pattern electroplating is completed, it is transferred to CNC machining, the half-hole is milled out, and then the circuit board with the half-hole processed is conveyed in the etching line at a high line speed of 6-7m / min to quickly etch away the exposed copper wire at the half-hole position. The etching amount is controlled at 0.8-1.2mil. After etching the copper wire and copper skin of the hole wall, a tin-plated dry film is applied to the half-hole. The dry film is covered in other positions except for the half-hole opening position, and then tin is applied to the pattern electroplating line. A layer of alkali-resistant etching tin layer is covered on the exposed hole wall copper, and the tin plating thickness needs to be >0.35mil. A secondary tin plating process is used to protect the exposed copper after CNC-cut half-holes. This prevents further erosion of the copper on the hole walls due to the via effect of the etching solution during the slowed-down etching process of the full-pattern design. This ensures the integrity of the copper on the hole walls and effectively controls the etching depth to within 0.8 mil. It also ensures that the area retention of the hole walls is greater than 90% of the original half-hole wall area.

[0038] This application effectively solves the problem of excessive etching of the hole wall caused by slow etching of thick copper lines, and ensures that the finished hole wall area of ​​the PTH half-hole after etching is more than 90% larger than the original half-hole hole wall area. Furthermore, this application utilizes existing equipment and chemical systems from conventional PCB processes, without increasing additional equipment costs. Through this processing technology, the integrity of the etched hole wall in PTH half-hole processing of copper circuit boards thicker than 3oz is improved. Traditional processes achieve a copper retention rate of less than 40% for PTH half-hole walls, while this process increases the copper retention rate to over 90%. Tin plating protection improves etching uniformity, eliminating the need to consider the amount of half-hole wall etching and allowing for flexible adjustment of the etching spray pressure to meet the requirements of circuit etching quality. Product reliability is improved; due to the half-hole wall area retention rate exceeding 90%, the instantaneous high current carrying capacity is increased by more than 30%. Soldering reliability is also improved; the complete tin-climbing area of ​​the hole wall is sufficiently large, and the tin-climbing height can be increased to over 75% of the board thickness.

[0039] In drilling processes, the specifications for drilling tools used for ultra-short slots are: drill bit diameter 0.5±0.05mm, cutter type 125RA ultra-short slot tool, and cutting edge length 8.7±0.5mm. The machining parameters for ultra-short slots include: rotational speed 85±5krpm, feed rate 0.5±0.05m / min, retraction rate 18±2m / min, and tool life: 700 holes. Within the industry, holes with an aspect ratio between 1.5 and 2 are defined as short slots, those with an aspect ratio between 1.3 and 1.5 are defined as ultra-short slots, and those with an aspect ratio less than 1.3 are defined as ultra-short slots.

[0040] In the negative dry film process, the dry film is HT115F copper-resistant dry film with a thickness of 1.5±0.2mil. During pattern electroplating, the tin plating parameters are: current 10-12A / SF, time 10-15min, and tin plating thickness 0.35-0.6mil.

[0041] The CNC machining includes roughing and finishing processes. The parameters for the roughing process are: groove width 1.8±0.2mm, cutter diameter 1.4±0.2mm, spindle speed 28±2Kr / min, feed rate 3±0.5mm / s, approach speed 7±4mm / s, retraction speed 415±20mm / s, and cutter life 1±0.1m. The parameters for the finishing process are: groove width 1.8±0.2mm, cutter diameter 1.0±0.2mm, spindle speed 28±2Kr / min, feed rate 6±0.5mm / s, approach speed 7±4mm / s, retraction speed 415±20mm / s, and cutter life 2.5±0.2m.

[0042] In the alkaline flash etching process, the conveying speed of the etching line is 6-7 m / min, the etching depth is controlled between 0.8-1.2 mil, and the parameters of the etching solution in the etching tank are: density 1.21±0.01, pH 8.35±0.25, Cu 2+ The concentration was 145±10 g / L, Cl - The concentration was 195±15 g / L, and the etching rate was 3±0.5 mil / min. The exposed copper wire at the half-hole location was quickly etched away by the etching lines.

[0043] In the process of semi-hole tin plating dry film, the vacuum lamination conditions are: dry film type HT115F, thickness 1.5mil, pressure 7kg / cm. 2 Speed ​​12m / min, vacuum degree <1kpa; vacuum lamination temperature 50-60℃, LDI exposure energy 400mj, energy grid 9-10 grids; dry film development conditions: linear speed 1.8±0.2m / min; temperature 29±1.4℃.

[0044] In the semi-hole tin plating process, the plating parameters are: current 6-8A / SF, time 8-10min. During the tin plating process, a dummy plating board of the same length and 20-30cm width is placed between each circuit board. Due to the low plating area, the dummy plating board is used to distribute the current. The length of the dummy plating board is the same as the length of the circuit board, and the width is 20-30cm. The tin plating solution is controlled as follows: H2SO4 concentration 188-212g / L, SnSO4 concentration 27-33g / L.

[0045] In the SES process, the stripping speed is controlled at 1.5m ± 0.2m / min, and the parameters of the etching solution in the etching tank are: density 1.21 ± 0.01, pH 8.35 ± 0.25, Cu 2+ 145±10g / L, Cl - The etching rate was 3±0.5 mil / min, and the parameters of the tin stripping solution in the tin stripping bath were: density 1.21±0.01 and acidity 5±1.5N. Because the half-hole was tinned twice, the combined tin thickness was between 0.7-1.0 mil.

[0046] Example 1: A thick copper metallization semi-hole processing technology includes: blanking → inner layer → lamination → drilling → copper electroplating → negative dry film → pattern electroplating (copper plating + tin plating 0.35-0.6mil) → CNC → alkaline flash etching (film stripping + rapid alkaline etching, but without tin stripping) → semi-hole tin plating dry film → semi-hole tin plating → SES (Strip Ink film removal + Etch etching + Strip Tin tin stripping) → AOI → solder mask → text → spray tin → forming → testing → final inspection → packaging; the core processes are described in detail below:

[0047] 1. Drilling: Drill holes on the laminated circuit board to prepare for subsequent PTH half-holes. The holes are ultra-short slots with an aspect ratio of less than 1.3. The drilling tool diameter is 0.5 mm, the tool type is 125RA ultra-short slot tool, the cutting edge length is 8.7 mm, and the machining parameters for the ultra-short slots are: rotation speed 85 krpm, feed rate 0.5 m / min, retraction rate 18 m / min, and tool life: 700 holes.

[0048] 2. Negative dry film: After electroplating copper on the circuit board, a negative dry film is applied. For extremely short slots attached to the outer ring, the compensation amount of the dry film coverage is greater than 0.23mm. The dry film is a copper-resistant dry film of model HT115F with a thickness of 1.5mil.

[0049] 3. Pattern electroplating: Copper and tin plating are performed on the inner wall of the extremely short slot to form a metal hole; the tin plating parameters are: current 10-12A / SF, time 10-15min, and tin plating thickness 0.35-0.6mil.

[0050] 4. CNC: Using a CNC machine tool to machine metal holes, milling out half-holes; CNC includes roughing and finishing processes. The parameters for the roughing process are: groove width 1.8mm, cutter diameter 1.4mm, spindle speed 28±2Kr / min, feed rate 3±0.5mm / s, down-cut speed 7±4mm / s, retraction speed 415mm / s, and cutter life 1m; the parameters for the finishing process are: groove width 1.8mm, cutter diameter 1.0mm, spindle speed 28±2Kr / min, feed rate 6±0.5mm / s, down-cut speed 7±4mm / s, retraction speed 415mm / s, and cutter life 2.5m.

[0051] 5. Alkaline flash etching: After stripping the film from the half-hole of the circuit board, perform rapid alkaline etching, without removing the tin section; the etching line feed rate is 6-7 m / min, the etching depth is controlled at 0.8-1.2 mil, and the parameters of the etching solution in the etching tank are: density 1.21±0.01, pH 8.35±0.25, Cu 2+ The concentration was 145±10 g / L, Cl - The concentration was 195±15 g / L and the etching rate was 3±0.5 mil / min.

[0052] 6. Half-hole tin plating dry film: A tin plating dry film is vacuum-pressed onto the circuit board, and then exposed and developed using an LDI (Liquid Optical Disc Reflector) to create an opening at the half-hole position. The vacuum lamination conditions are: dry film type HT115F, thickness 1.5 mil, pressure 7 kg / cm². 2Speed ​​12m / min, vacuum degree <1kpa; vacuum lamination temperature 50-60℃, LDI exposure energy 400mj, energy grid 9-10 grids; dry film development conditions: linear speed 1.8±0.2m / min; temperature 29±1.4℃.

[0053] 7. Half-hole tin plating: The circuit board is tin-plated through a patterned electroplating line, and a layer of alkali-resistant tin is plated on the copper wall of the exposed half-hole. The thickness of the tin layer is >0.35mil. The tin plating parameters are: current 6-8A / SF, time 8-10min. In the tin plating process, a dummy plate of the same length and width of 20-30cm is placed between each circuit board. Tin plating solution control: H2SO4 concentration 188-212g / L, SnSO4 concentration 27-33g / L.

[0054] 8. SES: The circuit board undergoes film removal, etching, and tin stripping to obtain a circuit board with half-holes. The tin stripping speed is controlled at 1.5m ± 0.2m / min. Since the half-hole area is tin-plated twice, the combined tin thickness is 0.7-1.0mil. The parameters of the etching solution in the etching tank are: density 1.21 ± 0.01, pH 8.35 ± 0.25, Cu2+ 145 ± 10g / L, Cl- 195 ± 10g / L, etching rate 3 ± 0.5mil / min. The parameters of the tin stripping solution in the tin stripping tank are: density 1.21 ± 0.01, acidity 5 ± 1.5N.

[0055] 9. Continue with the subsequent solder mask and packaging processes on the etched circuit board.

[0056] It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application shall be determined by the appended claims.

Claims

1. A thick copper circuit board metallization via processing, characterized by: The method comprises the following steps: Drilling: drilling holes on the laminated circuit board to prepare for subsequent PTH half-hole, wherein the holes are very short slot holes, and the length-width ratio of the very short slot holes is less than 1.3; Negative dry film: performing negative dry film on the circuit board after copper plating, and the compensation of dry film coverage on the very short slot hole is greater than 0.2 mm; Pattern plating: plating copper and tin on the inner wall of the very short slot hole to form a metal hole; CNC: processing the metal hole by using a CNC numerical control machine tool to mill and cut out a half-hole; Alkaline flash etching: performing rapid alkaline etching treatment on the circuit board with the cut-out half-hole, and then stripping the tin section; Half-hole tin plating dry film: vacuum pressing the tin plating dry film on the circuit board, and then forming a window at the half-hole position by LDI free expansion exposure and development; Half-hole tin plating: performing tin plating on the circuit board through a pattern plating line to plate a layer of alkali-etching-resistant tin layer on the copper wall of the half-hole, and the thickness of the tin layer is greater than 0.35 mil; SES: performing film stripping, etching and tin stripping treatment on the circuit board to obtain a circuit board with a half-hole.

2. The thick copper circuit board metallization via half-pit processing of claim 1, wherein: In the drilling process, the specification of the drilling tool for the very short slot hole is as follows: the diameter of the drilling tool is 0.5±0.05 mm, the tool type is 125RA very short slot tool, and the blade length is 8.7±0.5 mm.

3. The thick copper circuit board metallization via half-pit processing of claim 1, wherein: In the drilling process, the processing parameters of the very short slot hole include: the rotation speed is 85±5 krpm, the feeding speed is 0.5±0.05 m / min, the retracting speed is 18±2 m / min, and the service life is 700 holes.

4. The thick copper circuit board metallization via half-pit processing of claim 1 wherein: In the negative dry film process, the dry film is a copper plating resistant dry film with a model number of HT115F and a thickness of 1.5±0.2 mil.

5. The thick copper circuit board metallization via half-pit processing of claim 1 wherein: In the pattern plating, the tin plating parameters are as follows: the current is 10-12 A / SF, the time is 10-15 min, and the tin plating thickness is 0.35-0.6 mil.

6. The thick copper circuit board metallization via half-pit processing of claim 1 wherein: The CNC processing includes a roughing process and a finishing process, and the parameters of the roughing process are as follows: the slot width is 1.8±0.2 mm, the tool diameter is 1.4±0.2 mm, the rotation speed is 28±2 Kr / min, the feeding speed is 3±0.5 mm / s, the tool lowering speed is 7±4 mm / s, the tool retracting speed is 415±20 mm / s, and the milling tool service life is 1±0.1 m; and the parameters of the finishing process are as follows: the slot width is 1.8±0.2 mm, the tool diameter is 1.0±0.2 mm, the rotation speed is 28±2 Kr / min, the feeding speed is 6±0.5 mm / s, the tool lowering speed is 7±4 mm / s, the tool retracting speed is 415±20 mm / s, and the milling tool service life is 2.5±0.2 m.

7. The thick copper circuit board metallization via half-pit processing of claim 1 wherein: In the alkaline flash etching process, the etching line transfer speed is 6-7 m / min, the etching bite amount is controlled at 0.8-1.2 mil, and the etching liquid parameters in the etching tank are: density 1.21±0.01, pH 8.35±0.25, Cu 2+ concentration 145±10 g / L, Cl - concentration 195±15 g / L, etching rate 3±0.5 mil / min.

8. The thick copper circuit board metallization via half-pit processing of claim 1 wherein: In the process of half-hole tin plating dry film, the conditions of vacuum film pressing are: dry film model HT115F, thickness 1.5 mil, pressure 7 kg / cm 2 , speed 12 m / min, vacuum degree <1 kpa; vacuum film pressing temperature 50-60℃, LDI exposure energy 400 mj, energy grid 9-10 grids; dry film developing conditions: linear speed 1.8±0.2 m / min; temperature 29±1.4℃.

9. The thick copper circuit board metallization via half-pit processing of claim 1 wherein: In the half-hole tin plating process, the tin plating parameters are as follows: the current is 6-8 A / SF, the time is 8-10 min, and in the tin plating process, an accompanying plating plate with the same length and a width of 20-30 cm is arranged in the middle of each circuit board.

10. The thick copper circuit board metallization via half-pit processing of claim 1 wherein: In the SES process, the stripping speed of the tin section is controlled at 1.5 m ± 0.2 m / min, and the parameters of the etching solution in the etching tank are: density 1.21 ± 0.01, pH 8.35 ± 0.25, Cu 2+ 145 ± 10 g / L, Cl - 195 ± 10 g / L, etching rate 3 ± 0.5 mil / min, and the parameters of the stripping solution in the stripping tank are: density 1.21 ± 0.01, acidity 5 ± 1.5 N.