PTH connecting line horizontal flash plating copper manufacturing method

Abstract

The invention relates to a horizontal copper flash plating manufacturing method for a PTH connecting line, which comprises the following steps of: sequentially carrying out degumming, PTH, board finishing and copper flash plating on a PCB (Printed Circuit Board) multi-layer board, forming a thickened second copper layer on the PCB multi-layer board, sequentially carrying out deoiling, micro-etching, acid pickling and VCP copper plating treatment on the PCB multi-layer board through a VCP process, and forming a target copper layer on the basis of the second copper layer. Through the process design, the residence time from PTH to VCP electroplating is reduced, and meanwhile, the possibility that a to-be-electroplated plate is polluted is avoided through multiple times of cleaning of the multi-layer PCB in the PTH to VCP electroplating through a reliable closed environment and design, so that the reliability between PTH thin copper and electroplating copper is improved.

Description

Technical Field

[0001] The embodiment of the present invention relates to the technical field of PCB manufacturing, and specifically to a method for manufacturing a PTH line with horizontal flash copper plating. Background Art

[0002] With the development of high-density interconnection circuit board (HDI) products towards higher density interconnection, higher levels and mixed pressure of multiple materials, the reliability of multi-level blind hole copper plating has been adjusted to a higher reliability. Due to some defects in the traditional horizontal PTH to vertical VCP electroplating process, such as micro cracks between the blind hole copper plating after the product is placed at high temperature, the resistance is unstable, and it is difficult to meet the reliability of blind hole copper plating of higher-order blind holes and mixed pressure types of HDI circuit boards.

[0003] Due to the intermittent problem of copper plating from PTH to VCP, the finished board needs to be dried after the PTH process, resulting in insufficient wetting of the board after VCP, especially the blind hole. In addition, there is a certain degree of oxidation in the intermittent board between PTH and VCP. Since PTH is a thin layer of deposited copper, strong acid or micro-etching process cannot be used in the VCP pre-treatment, and there is insufficient removal of oxidation in the blind hole. When copper is plated on the oxide layer, the bonding between the plating and the base copper will not be strong. Finally, when the product encounters high temperature, the plate expands and contracts due to heat and cold, and micro-cracks appear between the plating and the base copper; thus, defective products are produced. Summary of the invention

[0004] In view of the above problems, an embodiment of the present invention provides a method for manufacturing horizontal flash copper plating of PTH connection lines, which is used to solve the problem in the prior art that micro cracks appear in the plating layer and the base copper after the plate material expands and contracts when the product encounters high temperature, thereby producing defective products.

[0005] According to one aspect of an embodiment of the present invention, a method for manufacturing a PTH line with horizontal flash copper plating is provided, the method comprising: Removing glue, obtaining the PCB multilayer board after drilling, and removing the resin glue generated during the drilling process, exposing the inner copper layer of the PCB multilayer board; PTH, forming a first copper layer on the PCB multilayer board by copper deposition; Whole board, finishing the PCB multilayer board after copper deposition and transferring it to the copper plating tank; Flash copper plating, copper plating the surface of the PCB multilayer board in a copper plating tank to form a second copper layer on the surface of the first copper layer; The VCP process sequentially performs degreasing, micro-etching, pickling, and VCP copper plating on the PCB multilayer board to form a target copper layer on the basis of the second copper layer.

[0006] In some optional embodiments, in the PTH step, a first copper layer is formed on the hole wall of the PCB multilayer board by chemical copper deposition or electrolytic copper deposition.

[0007] In some optional embodiments, after the PTH step and between the whole board step, the process further includes: First water washing, cleaning the PCB multilayer board for the first time with clean water; Second water washing, cleaning the PCB multilayer board for the second time with clean water; Strong wind is used to dry the moisture on the surface of the PCB multilayer board.

[0008] In some optional embodiments, the whole board step specifically includes: arranging the PCB multilayer board to one side of the flash copper plating equipment, and contacting the PCB multilayer board with a conductive roller when in the copper plating tank.

[0009] In some optional embodiments, after the whole board step and before the flash copper plating step, the process further includes: First pickling: The surface of the PCB multilayer board is infiltrated with pickling liquid.

[0010] In some optional embodiments, in the flash copper plating step, By energizing the conductive roller, the copper ions in the electroplating tank are electroplated onto the PCB multilayer board to form a second copper layer; wherein the copper ions in the electroplating tank are dissolved in the auxiliary tank by using water-soluble copper sulfate, which is connected to the copper plating main tank by a filter pump, and the water-soluble copper sulfate is pumped into the electroplating tank under the action of the filter pump to obtain it.

[0011] In some optional embodiments, the electroplating solution of the electroplating tank is composed of CUSO 4 , H 2 SO 4 , leveling agent, brightener and wetting agent.

[0012] In some optional embodiments, the second copper layer is 5 μm-10 μm thicker than the first copper layer.

[0013] In some optional embodiments, the PCB multilayer board is subjected to degreasing, micro-etching, pickling, and VCP copper plating treatment in sequence, specifically including: Degreasing: Use an acidic degreasing agent to clean the surface of the PCB multilayer board and infiltrate the surface of the PCB multilayer board; Micro-etching, coating the PCB multilayer board with an etchant to roughen the second copper layer of the PCB multilayer board; The second pickling, using pickling liquid to clean the PCB multilayer board after micro-etching, to remove the residual moisture on the PCB multilayer board; VCP copper plating, electroplating the PCB multilayer board by vertical continuous electroplating to form a target copper layer on the basis of the second copper layer.

[0014] In some optional embodiments, after the micro-etching and before the second pickling, the process further includes: The third water washing is to wash the PCB multilayer board for the third time with clean water; The fourth water washing is to wash the PCB multilayer board for the fourth time with clean water.

[0015] The method for manufacturing horizontal flash copper plating of PTH connection lines of the present invention has the beneficial effect that: the present invention sequentially removes glue, performs PTH, completes the board, and performs flash copper plating on the PCB multilayer board to form a thickened second copper layer on the PCB multilayer board, and then sequentially performs degreasing, micro-etching, pickling, and VCP copper plating on the PCB multilayer board through the VCP process to form a target copper layer on the basis of the second copper layer. Through the above-mentioned process design, the residence time between PTH and VCP electroplating is reduced, and at the same time, the PTH to VCP electroplating is repeatedly cleaned of the PCB multilayer board through a reliable closed environment and design, avoiding the possibility of contamination of the plate to be electroplated, thereby improving the reliability between PTH thin copper and electroplated copper.

[0016] The above description is only an overview of the technical solution of the embodiment of the present invention. In order to more clearly understand the technical means of the embodiment of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are only used to illustrate the embodiments and are not to be considered as limiting the present invention. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings. In the accompanying drawings: Figure 1 A schematic flow chart of a method for manufacturing a PTH line with horizontal flash copper plating according to Example 1 of the present invention is shown; Figure 2 A schematic diagram of cleaning after the PTH step of Example 1 provided by the present invention is shown; Figure 3 A schematic diagram of sequentially performing degreasing, micro-etching, pickling, and VCP copper plating treatments on a PCB multilayer board according to Example 3 provided by the present invention is shown. DETAILED DESCRIPTION

[0018] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0019] Embodiment 1, See also Figure 1 According to an embodiment of the present invention, a method for manufacturing horizontal flash copper plating of a PTH connection is provided, which is used to manufacture a PCB board; the present invention ensures that the copper plating process after PTH is connected to the copper plating process after VCP in a short time, thereby avoiding the oxidation of the copper surface due to the long interval between PTH and VCP, and the quality problems caused by the exposure of the electroplated product to the poor air pollution in the large environment. The method comprises: 110, glue removal, obtain the PCB multilayer board after drilling, and remove the resin glue generated during the drilling process to expose the inner copper layer of the PCB multilayer board; in step 110, the resin glue remaining after drilling the PCB multilayer board can be removed by any of the methods of vacuum plasma cleaning, chemical dissolution, mechanical removal, thermal stripping, and potassium permanganate. In this solution, the epoxy resin glue can be chemically dissolved by organic solvents such as acetone, acetic acid, and methanol to clean the resin glue. Before removing the glue, the target PTH hole needs to be drilled in the PCB multilayer board, and the previous drilling process can be mechanical drilling or laser drilling according to the drilling data.

[0020] 120, PTH, forming a first copper layer on the PCB multilayer board by copper deposition; in step 120, PTH is copper-plated on the PTH hole of the PCB multilayer board by copper deposition or electroplating to form a first copper layer. In this embodiment, PTH is copper deposition of the circuit board, and its main function is to form a conductive first copper layer on the PCB substrate for subsequent electroplating and welding processes. This layer of copper not only provides the conductivity of the circuit board, but also ensures that the electronic components on the circuit board can be correctly connected and communicated. Copper deposition technology deposits a copper layer on the hole wall of the circuit board through a chemical or electroplating process to achieve electrical connection, enhance mechanical strength, and ensure signal integrity and conductive performance.

[0021] 130, whole board, arrange the PCB multilayer board after copper plating and transfer it to the copper plating tank; in step 130, the whole board step specifically includes: arrange the PCB multilayer board to the side of the copper plating equipment for flash copper plating, and contact the PCB multilayer board with the conductive roller when in the copper plating tank. Through the whole board step, the PCB multilayer board can be clamped in the state used for copper plating of the PCB multilayer board, arrange the PCB multilayer board to the side of the copper plating equipment for flash copper plating, and transfer it to the copper plating tank through the logistics line to connect with the conductive roller of the copper plating tank.

[0022] 140, flash copper plating, copper plating the surface of the PCB multilayer board in a copper plating tank to form a second copper layer on the surface of the first copper layer; in step 140, flash copper plating means copper plating the PCB multilayer board for the second time before VCP copper plating to form a second copper plating layer to thicken the original first copper layer. With the thickened first copper layer, the second copper layer can be prevented from being completely etched away when adding degreasing and micro-etching in the VCP pre-treatment.

[0023] 150, VCP process, degreasing, micro-etching, pickling, and VCP copper plating are performed on the PCB multilayer board in sequence to form a target copper layer on the basis of the second copper layer. In step 150, the PCB multilayer board is degreasing, micro-etching, pickling, and VCP copper plating are performed in sequence, specifically including: degreasing using an acidic degreasing agent to clean the surface of the PCB multilayer board and infiltrate the surface of the PCB multilayer board; micro-etching is to apply an etchant on the PCB multilayer board to coarsen the second copper layer of the PCB multilayer board; the second pickling is to clean the PCB multilayer board after micro-etching with an acidic solution to remove the residual moisture of the PCB multilayer board; VCP copper plating is to electroplate the PCB multilayer board by vertical continuous electroplating to form a second copper layer on the surface of the first copper layer.

[0024] Steps 110-140 of the present invention can be completed in the same production line, and step 150 can be completed in another production line. The PTH to VCP electroplating is carried out through a reliable closed environment and multiple cleanings of the PCB multilayer board by design, thereby avoiding the possibility of the electroplated board being contaminated, thereby improving the reliability between the PTH thin copper and the electroplated copper.

[0025] The present invention sequentially removes glue, performs PTH, performs whole board, and performs flash copper plating on the PCB multilayer board, forms a thickened second copper layer on the PCB multilayer board, and then sequentially performs degreasing, micro-etching, pickling, and VCP copper plating on the PCB multilayer board through a VCP process, and forms a target copper layer on the basis of the second copper layer. Through the above process design, the residence time between PTH and VCP electroplating is reduced, and at the same time, the PTH to VCP electroplating is repeatedly cleaned on the PCB multilayer board through a reliable closed environment and design, avoiding the possibility of contamination of the plate to be electroplated, thereby improving the reliability between PTH thin copper and electroplated copper.

[0026] In some optional embodiments, see the attached Figure 2 , after the PTH step and between the whole board steps, it also includes: 210, first water washing, using clean water to wash the PCB multilayer board for the first time; 220, second water washing, using clean water to wash the PCB multilayer board for the second time; 230, strong wind drying, drying the moisture on the surface of the PCB multilayer board. In this embodiment, the present invention washes the PCB multilayer board after copper deposition by two water washings after the PTH step, avoiding the quality problems caused by residual copper deposition solution on the PCB multilayer board and exposure to poor air pollution in the large environment; improving the quality of the PCB multilayer board.

[0027] In some optional embodiments, after the whole board step and before the flash copper plating, the process further includes: first pickling: soaking the board surface of the PCB multilayer board with a pickling solution. In this embodiment, soaking the board surface avoids problems such as bubbles in blind holes during the copper plating process.

[0028] Embodiment 2: Based on Example 1, the present invention further defines the step of flash copper plating in 140. Specifically, by energizing the conductive roller, the copper ions in the plating tank are electroplated onto the PCB multilayer board to form a second copper layer; The second copper layer is formed by plating a layer of base copper with a thickness of about 5μm~10μm on the surface of the first copper layer deposited in the via hole. The base copper can be used to increase degreasing and micro-etching in the pre-VCP treatment to prevent the second copper layer from being completely etched away.

[0029] The copper ions in the electroplating tank are obtained by dissolving water-soluble copper sulfate in the auxiliary tank, connecting the copper plating main tank by a filter pump, and pumping the water-soluble copper sulfate into the electroplating tank under the action of the filter pump. In this embodiment, since the horizontal copper plating line cannot adopt the direct copper ball electrolytic reduction process, the copper ion supply of the horizontal copper plating line of the present invention is supplied by the liquid medicine, and water-soluble copper sulfate is dissolved in the auxiliary tank, connected to the copper plating main tank by a filter pump, and the water-soluble copper sulfate is pumped into the electroplating tank under the action of the filter pump.

[0030] In the above embodiment, the electroplating solution in the electroplating tank is composed of CUSO 4 , H 2 SO 4 , leveling agent, brightener and wetting agent. Specifically, the control range of the content of the electroplating bath solution for flash copper is: CUSO4: 240~260g / L, used to provide a source for electroplating copper.

[0031] H2SO4: 30~45g / L, used to provide conductivity.

[0032] Leveling agent: 4~13ml / L, used to balance the uniformity of current distribution.

[0033] Brightener: 0.3~1.3ml / L, used to change the crystal surface index, make the metal surface smooth and refined, so as to obtain a bright coating. Brightener is adsorbed at the high potential of the electroplated layer surface, so that metal ions produce a certain resistance when precipitating, and the low potential is easy to precipitate, so that the coating becomes flat and smooth, achieving the purpose of brightness.

[0034] Wetting agent: 5~12.5ml / L, the wetting agent can be adsorbed on the cathode surface, reducing the interfacial tension between the electrode and the solution, making it easy for hydrogen bubbles to leave the electrode surface, thereby preventing or reducing the generation of pinholes in the coating, enhancing the wetting effect of the substrate surface during the electroplating process, and ensuring a uniform and fine coating.

[0035] Embodiment 3: Based on Example 1 or Example 2, the present invention further defines the steps of 150, VCP process on the basis of Example 1 or Example 2. Degreasing, micro-etching, pickling, and VCP copper plating are performed on the PCB multilayer board in sequence, see Figure 3 , including: 310, degreasing, using an acidic degreasing agent to clean the surface of the PCB multilayer board and soak the surface of the PCB multilayer board; in step 310, the acidic degreasing agent is used to clean the pollution on the board surface, remove the pollution of the product in the air during the PTH to VCP process, and soak the board surface to make the board surface easier to contact the medicine of the subsequent process.

[0036] 320, micro-etching, applying an etchant to the PCB multilayer board to roughen the second copper layer of the PCB multilayer board; in step 320, micro-etching refers to the process of applying a layer of etchant on the surface of the PCB multilayer board, and then slightly corroding a part of the surface of the copper plate by chemical methods. The purpose of this process is to remove the oxide layer, dirt, etc. on the copper surface to form a microscopically rough surface, thereby enhancing the bonding force between the surface layer of the copper foil and the subsequent chemical copper layer or the subsequent copper plating layer, and ensuring the performance and reliability of the circuit board. After the micro-etching step is completed, the PCB can also be washed for the third time, and the PCB multilayer board is washed for the third time with clean water; the fourth water wash, the PCB multilayer board is washed for the fourth time with clean water. Clean the etching liquid on the surface of the PCB multilayer board.

[0037] 330, the second pickling, the PCB multilayer board after micro-etching is cleaned by pickling liquid to remove the residual moisture of the PCB multilayer board; in step 330, the PCB multilayer board after micro-etching or the PCB multilayer board after the fourth water washing is cleaned by the second pickling, the etching liquid or residual moisture is cleaned to avoid contaminating the copper tank, and the copper surface to be copper-plated is deoxidized.

[0038] 340, VCP copper plating, electroplating the PCB multilayer board by vertical continuous electroplating to form a target copper layer on the basis of the second copper layer. In step 340, the workpiece can be vertically suspended in the electroplating tank and electroplated by continuous conveying, so that copper ions are uniformly deposited on the surface of the workpiece under the action of the electric field to form the desired target copper layer.

[0039] In the present invention, after flash copper plating, the pre-treatment method can be strengthened before the subsequent copper plating of VCP, so that the board with certain contamination can be treated with a relatively low potion to remove the contamination, and the wettability of the surface of the plate to be electroplated is increased, thereby avoiding the problem of air bubbles in blind holes or through holes, and avoiding the situation where bubbles block electroplating, resulting in copper not being plated in the hole.

[0040] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. Similarly, in order to simplify the present invention and help understand one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, the various features of the embodiments of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. Wherein, the claims that follow the specific embodiment are hereby expressly incorporated into the specific embodiment, wherein each claim itself is a separate embodiment of the present invention.

[0041] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and further may be divided into a plurality of submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive.

[0042] It should be noted that the above embodiments illustrate the present invention rather than limit it, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets shall not be construed as a limitation on the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of multiple such elements. The present invention may be implemented with the aid of hardware comprising several different elements and with the aid of appropriately programmed computers. In a unit claim that lists several systems, several of these systems may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be understood as limitations on the order of execution.

Claims

1. A method for manufacturing horizontal flash copper plating of PTH connection, characterized in that: The method comprises: Removing glue, obtaining the PCB multilayer board after drilling, and removing the resin glue generated during the drilling process, exposing the inner copper layer of the PCB multilayer board; PTH, forming a first copper layer on the PCB multilayer board by copper deposition; Whole board, finishing the PCB multilayer board after copper deposition and transferring it to the copper plating tank; Flash copper plating, copper plating the surface of the PCB multilayer board in a copper plating tank to form a second copper layer on the surface of the first copper layer; The VCP process sequentially performs degreasing, micro-etching, pickling, and VCP copper plating on the PCB multilayer board to form a target copper layer on the basis of the second copper layer.

2. The method for manufacturing horizontal flash copper plating of PTH connection lines according to claim 1, characterized in that: In the PTH step, a first copper layer is formed on the hole wall of the PCB multilayer board by chemical copper deposition or electrolytic copper deposition.

3. The method for manufacturing horizontal flash copper plating of PTH connection lines according to claim 1, characterized in that: After the PTH step and between the whole board step, the method further comprises: First water washing, cleaning the PCB multilayer board for the first time with clean water; Second water washing, cleaning the PCB multilayer board for the second time with clean water; Strong wind is used to dry the moisture on the surface of the PCB multilayer board.

4. The method for manufacturing horizontal flash copper plating of PTH connection lines according to claim 1, characterized in that: The whole board step specifically includes: arranging the PCB multilayer board to one side of the flash copper plating equipment, and contacting the PCB multilayer board with a conductive roller when in the copper plating tank.

5. The method for manufacturing horizontal flash copper plating of PTH connection lines according to claim 4, characterized in that: After the whole board step and before the flash copper plating step, the method further includes: First pickling: The surface of the PCB multilayer board is infiltrated with pickling liquid.

6. The method for manufacturing horizontal flash copper plating of PTH connection lines according to claim 5, characterized in that: In the flash copper plating step, By energizing the conductive roller, the copper ions in the electroplating tank are electroplated onto the PCB multilayer board to form a second copper layer; wherein the copper ions in the electroplating tank are dissolved in the auxiliary tank by using water-soluble copper sulfate, which is connected to the copper plating main tank by a filter pump, and the water-soluble copper sulfate is pumped into the electroplating tank under the action of the filter pump to obtain it.

7. The method for manufacturing horizontal flash copper plating of PTH connection lines according to claim 6, characterized in that: The electroplating solution of the electroplating tank is made of CUSO 4 , H 2 SO 4 , leveling agent, brightener and wetting agent.

8. The method for manufacturing horizontal flash copper plating of PTH connection lines according to claim 6, characterized in that: The second copper layer is 5 μm to 10 μm thicker than the first copper layer.

9. The method for manufacturing horizontal flash copper plating of PTH connection lines according to claim 1, characterized in that: The PCB multilayer board is subjected to degreasing, micro-etching, pickling, and VCP copper plating treatment in sequence, specifically including: Degreasing: Use an acidic degreasing agent to clean the surface of the PCB multilayer board and infiltrate the surface of the PCB multilayer board; Micro-etching, coating the PCB multilayer board with an etchant to roughen the second copper layer of the PCB multilayer board; The second pickling, using pickling liquid to clean the PCB multilayer board after micro-etching, to remove the residual moisture on the PCB multilayer board; VCP copper plating, electroplating the PCB multilayer board by vertical continuous electroplating to form a target copper layer on the basis of the second copper layer.

10. The method for manufacturing horizontal flash copper plating of PTH connection lines according to claim 1, characterized in that: After the micro-etching and before the second pickling, the method further includes: The third water washing is to wash the PCB multilayer board for the third time with clean water; The fourth water washing is to wash the PCB multilayer board for the fourth time with clean water.

Images