A manufacturing method for preventing separation of hole walls of square slot holes of a double-sided circuit board after tin spraying

Abstract

The application discloses a kind of prevent the production method of double-sided circuit board square slot hole tin spraying after hole wall separation, comprising the following steps: step S1, square slot hole is drilled, comprising the following steps: in the R angle of square slot hole four corners Drilling positioning pilot hole;Multiple round holes are drilled in the middle of square slot hole, and the round hole is tangent with the slot hole wall of the four sides of square slot hole;Slot hole is drilled in the four sides of square slot hole, wherein two first slot holes for controlling the slot width of square slot hole are drilled first, then two second slot holes in the length direction of square slot hole are drilled;Plate is baked, temperature is Tg+(5-10) ℃, time is 3.5-4.5h;Remove slag;Electroplating, after electroplating, the one-side copper thickness of square slot hole wall is 27-32um;Plate is baked, temperature is 135-145 ℃, time is 1-1.5h;Tin spraying, make square slot hole wall one-side tin thickness 5-10um.The production method for preventing double-sided circuit board square slot hole tin spraying after hole wall separation provided by the application avoids the hole wall separation of double-sided circuit board square slot hole after tin spraying, so as to improve the reliability of similar circuit board.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, and specifically to a manufacturing method for preventing the separation of the hole walls after soldering of square slot holes in double-sided circuit boards. Background Technology

[0002] With the rapid development of electronic devices towards miniaturization and high-density interconnection, double-sided circuit boards (PCBs) are widely used in communications, consumer electronics, and automotive electronics due to their compact structure and flexible wiring. In PCB design, square slot holes (rectangular or square slotted holes) are often used to connect high-power devices, heat dissipation modules, or mechanical fixing components due to their special geometry, achieving both electrical and structural functions. However, during surface treatment processes, especially after hot air leveling and tin plating, square slot holes are prone to defects such as separation of the copper layer from the substrate, severely affecting product reliability and yield.

[0003] Therefore, it is necessary to provide a new process to solve the above-mentioned technical problems. Summary of the Invention

[0004] The purpose of this invention is to provide a manufacturing method for preventing the separation of the hole walls after tin plating of square slot holes in double-sided circuit boards. This method can avoid the separation of the hole walls after tin plating of square slot holes in double-sided circuit boards, thereby improving the reliability of similar circuit boards.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preventing the hole wall from separating after solder plating in square slot holes of a double-sided circuit board includes the following steps:

[0007] Step S1, drilling a square groove, includes the following steps:

[0008] Step S11: Drill positioning pilot holes at the four corners (R-angle) of the square slot hole;

[0009] Step S12: Drill multiple round holes in the center of the square slot, with the round holes tangent to the slot walls on all four sides of the square slot.

[0010] Step S13: Drill slots on all four sides of the square slot, first drilling two first slots to control the width of the square slot, and then drilling two second slots along the length of the square slot.

[0011] Step S2: Baking plate, temperature Tg+(5-10)℃, time 3.5-4.5h;

[0012] Step S3, removing adhesive residue. The temperature of the adhesive residue removal solution is controlled at 75±5℃. Mn in the solution... 7+ Controlled at 55-65 g / L, Mn 6 + The concentration should be controlled at <30g / L, and the amount of adhesive removed should be controlled at 0.1-0.3mg / cm2;

[0013] Step S4, electroplating, the concentration of sulfuric acid in the electroplating solution is controlled at 60-90g / L, the concentration of copper sulfate is controlled at 100-120mL / L, the chloride ion concentration is controlled at 50-80ppm, and the copper thickness on one side of the hole wall after electroplating is 27-32um.

[0014] Step S5: Baking plate, temperature 135-145℃, time 1-1.5h;

[0015] Step S6: Spray tin to make the tin thickness on one side of the square slot hole wall 5-10um.

[0016] Furthermore, in step S1, the grooving hole is drilled using an EA 0.7mm grooving cutter, a two-piece stacked drilling process, a feed rate of 0.3m / min, and a lifespan of 1000 holes.

[0017] Furthermore, in step S11, the diameter of the positioning hole is 0.4 mm.

[0018] Furthermore, in step S2, when the circuit board is a double-sided board, baking is required both before and after drilling the square slot; when the circuit board is a multilayer board, baking is required after drilling the square slot.

[0019] Furthermore, in step S3, the adhesive removal temperature is 85±3℃, and the adhesive removal rate is 0.15-0.4 mg / cm³. 2 .

[0020] Further, step S6 includes the following steps:

[0021] Tin immersion: The copper content in the tin bath is 0.5-0.9 wt%, the tin bath temperature is 260-270℃, and the immersion time is 2.5s.

[0022] After tinning through the rosin section, the temperature of the front and rear air knives is 340-380℃, and the air pressure is 2.5-4.0Kg / cm². 2 The copper content is controlled between 0.6% and 0.8% every 300 square meters of tin bath produced.

[0023] Compared with the prior art, the manufacturing method for preventing the separation of hole walls after tin plating in square slot holes of double-sided circuit boards provided by the present invention has the following advantages:

[0024] The present invention provides a method for preventing the separation of hole walls after tin plating in square slot holes of double-sided circuit boards. When drilling square slot holes, positioning pilot holes are first drilled at the four corners, and then multiple round holes are drilled in the middle of the square slot hole to ensure that the middle substrate is completely drilled through. Finally, slot holes are drilled on the four sides to control the slot width and slot length, which can prevent the drilling of square slot holes from being misaligned and improve the drilling accuracy of square slot holes. After subsequent electroplating and tin plating processes, the copper and tin thickness of the hole walls are more uniform, avoiding the separation of hole walls after tin plating in square slot holes of double-sided circuit boards, thereby improving the reliability of similar circuit boards.

[0025] II. The manufacturing method for preventing hole wall separation after tin plating in square slot holes of double-sided circuit boards provided by the present invention solves the hole wall separation problem from multiple dimensions, including structural stability, interface cleanliness and plating uniformity, by controlling drilling accuracy, optimizing thermal management and coordinating the adjustment of metal layer process parameters, thereby improving the reliability of circuit boards. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the process of drilling square slots in the manufacturing method of the present invention. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described below.

[0029] It should be noted that the descriptions of these embodiments are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] A method for preventing the hole wall from separating after solder plating in square slot holes of a double-sided circuit board includes the following steps:

[0031] Step S1, drill a square groove, as shown Figure 1 As shown, it includes the following steps:

[0032] Step S11: Drill positioning pilot holes 1 at the four corners R of the square slot hole. Specifically, the diameter of the positioning pilot holes 1 is 0.4mm to ensure accurate drilling positioning.

[0033] Step S12: Drill multiple round holes 2 in the middle of the square slot hole. The round holes are tangent to the slot hole walls on all four sides of the square slot hole to ensure that the middle substrate is completely drilled through and to reduce residual stress.

[0034] Step S13: Drill slots on all four sides of the square slot. First, drill two first slots 31 to control the width of the square slot, and then drill two second slots 32 along the length of the square slot. Drill the slots using an EA 0.7mm slotting cutter, a two-piece stacked drilling process, a feed rate of 0.3m / min, and a lifespan of 1000 holes. The step-by-step machining of the slots can avoid misalignment, improve the accuracy of the hole wall structure, and provide a uniform foundation for subsequent copper plating / tin plating.

[0035] Step S2: Baking plate, temperature Tg+(5-10)℃, time 3.5-4.5h;

[0036] When the circuit board is a double-sided board, baking is required both before and after drilling the square slots; when the circuit board is a multilayer board, baking is only required after drilling the square slots. The purpose of the baking process is to: remove residual moisture and volatiles from the drilled holes; release drilling stress and reduce substrate deformation; and improve the resin condition of the hole walls, enhancing adhesion.

[0037] Step S3, removing adhesive residue. The temperature of the adhesive residue removal solution is controlled at 75±5℃. Mn in the solution... 7+ Controlled at 55-65 g / L, Mn 6 + The concentration should be controlled at <30g / L, and the amount of adhesive removed should be controlled at 0.1-0.3mg / cm2;

[0038] Specifically, the adhesive removal temperature is 85±3℃, and the adhesive removal rate is 0.15-0.4 mg / cm³. 2 Thoroughly clean the adhesive residue from the hole walls to ensure a tight bond between the electroplated copper layer and the substrate.

[0039] Step S4, electroplating: The concentration of sulfuric acid in the electroplating solution is controlled at 60-90 g / L, the concentration of copper sulfate is controlled at 100-120 mL / L, and the chloride ion concentration is controlled at 50-80 ppm. After electroplating, the copper thickness on one side of the hole wall is 27-32 μm. The copper thickness on one side of the hole wall can provide sufficient mechanical support and reduce copper layer peeling caused by thermal expansion differences.

[0040] Step S5: Baking plate, temperature 135-145℃, time 1-1.5h;

[0041] At this point, the baking process serves to: remove residual chemicals from electroplating; release internal stress in the plating layer to prevent cracking; and prevent delamination during subsequent high-temperature processes.

[0042] Step S6, soldering, to make the solder thickness on one side of the square slot hole wall 5-10um; specifically including the following steps:

[0043] The copper content in the tin bath is 0.5-0.9wt%, the tin bath temperature is 260-270℃, and the immersion time is 2.5s, so that tin does not accumulate at the four corners R of the square slot hole;

[0044] After tinning through the rosin section, the temperature of the front and rear air knives is 340-380℃, and the air pressure is 2.5-4.0Kg / cm². 2 The copper content is controlled between 0.6% and 0.8% every 300 square meters of tin bath produced.

[0045] This tin-plating process can reduce the impact of thermal stress on the copper layer.

[0046] This invention provides a method for preventing hole wall separation after tin plating in square slot holes of double-sided circuit boards. By controlling drilling accuracy, optimizing thermal management, and coordinating the adjustment of metal layer process parameters, the method addresses the hole wall separation problem from multiple dimensions, including structural stability, interface cleanliness, and plating uniformity, thereby improving the reliability of the circuit board.

[0047] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for preventing the separation of hole walls after solder plating in square slot holes of a double-sided circuit board, characterized in that, Includes the following steps: Step S1, drilling a square groove, includes the following steps: Step S11: Drill positioning pilot holes at the four corners (R-angle) of the square slot hole; Step S12: Drill multiple round holes in the center of the square slot, with the round holes tangent to the slot walls on all four sides of the square slot. Step S13: Drill slots on all four sides of the square slot, first drilling two first slots to control the width of the square slot, and then drilling two second slots along the length of the square slot. The grooving hole is drilled using an EA 0.7mm grooving cutter, a two-blade stacked drilling process, a feed rate of 0.3m / min, and a lifespan of 1000 holes; Step S2: Baking plate, temperature Tg+(5-10) ℃, time 3.5-4.5h; Step S3, removing adhesive residue. The temperature of the adhesive residue removal solution is controlled at 75±5°C. Mn in the solution... 7+ Controlled at 55-65 g / L, Mn 6+ The concentration should be controlled at <30g / L, and the amount of adhesive removed should be controlled at 0.1-0.3mg / cm². The adhesive removal temperature is 85±3℃, and the adhesive removal rate is 0.15-0.4 mg / cm³. 2 ; Step S4, electroplating, the concentration of sulfuric acid in the electroplating solution is controlled at 60-90g / L, the concentration of copper sulfate is controlled at 100-120mL / L, the chloride ion concentration is controlled at 50-80ppm, and the copper thickness on one side of the hole wall after electroplating is 27-32um. Step S5: Baking plate, temperature 135-145 ℃, time 1-1.5h; Step S6, soldering, to make the solder thickness on one side of the square slot hole wall 5-10um, specifically including the following steps: Tin immersion: The copper content in the tin bath is 0.5-0.9 wt%, the tin bath temperature is 260-270℃, and the immersion time is 2.5s. After tinning through the rosin section, the temperature of the front and rear air knives is 340-380℃, and the air pressure is 2.5-4.0Kg / cm². 2 ; The copper in the tin bath is removed once every 300 square meters of production, and the copper content is controlled at 0.6-0.8%.

2. The manufacturing method for preventing the separation of the hole wall after solder spraying in a square slot hole of a double-sided circuit board according to claim 1, characterized in that, In step S11, the diameter of the positioning hole is 0.4 mm.

3. The manufacturing method for preventing the separation of the hole wall after solder spraying in a square slot hole of a double-sided circuit board according to claim 1, characterized in that, In step S2, when the circuit board is a double-sided board, it needs to be baked both before and after drilling the square slot; when the circuit board is a multilayer board, it needs to be baked after drilling the square slot.

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