Pulse copper plating process with low TOC (total organic carbon) and high deep plating capacity

Abstract

The invention discloses a pulse copper plating process with low TOC and high deep plating capacity. The pulse copper plating process comprises the following steps that 1, pretreatment is conducted, specifically, a substrate is subjected to cleaning, oil removing and acid etching rust removing treatment; 2, surface treatment: treating the surface of the substrate by using a treating agent; thirdly, acid copper sulfate copper plating is conducted, specifically, the treated substrate is placed in a copper plating tank, and electroplating is conducted through a copper electroplating solution of high-purity copper sulfate with the purity being 99.8%; 4, post-treatment is conducted, specifically, the copper-plated substrate is cleaned and dried; step 5, inspection: performing external inspection and performance inspection on the dried substrate; by adding the electroplating liquid, reducing the bath changing frequency and reducing the sewage treatment capacity, the production cost is reduced, the pollution to the environment is greatly reduced, and the production cost of an enterprise is reduced; tOC is low under the same load condition, the cylinder changing frequency is reduced, and wastewater discharge is reduced; meanwhile, due to low TOC, the service life of the additive can be doubled, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of PCB electroplating, in particular to a pulse copper plating process with low TOC and high deep plating capability. Background Art

[0002] TOC is the abbreviation of Total Organic Carbon. The content of organic matter in the low TOC electroplating solution is low, which is one of the ways to improve the quality of the coating. The high deep plating ability is mainly aimed at workpieces with complex shapes or parts with deep holes, grooves and other structures to achieve a more uniform and complete coating coverage, which realizes the combination of low TOC and high deep plating ability. Pulse copper plating can easily cause a high frequency of slot changing.

[0003] As the whole society's environmental awareness increases and enterprises attach more importance to cost advantages, we must not only produce high-quality products, but also meet the requirements of sewage treatment, reduce the amount of sewage treatment, and reduce pollution to the environment, thereby further reducing the production cost requirements of enterprises. The existing pulse copper plating process cannot reduce the frequency of tank replacement, thereby reducing the amount of sewage treatment, thereby increasing the production cost of enterprises. Therefore, we proposed a low TOC high deep plating ability pulse copper plating process to solve the above-mentioned problems. Summary of the invention

[0004] The object of the present invention is to provide a pulse copper plating process with low TOC and high deep plating capability to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A pulse copper plating process with low TOC and high deep plating capability comprises the following steps:

[0007] Step 1: Pretreatment: Clean and degrease the substrate, and perform acid etching and rust removal;

[0008] Step 2: Surface treatment: Use a surface treatment agent to treat the surface of the substrate;

[0009] Step 3: Acid copper sulfate copper plating: Place the treated substrate into a copper plating tank and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating;

[0010] Step 4: Post-processing: cleaning and drying the copper-plated substrate;

[0011] Step 5: Inspection: Perform appearance inspection and performance inspection on the dried substrate.

[0012] As a further solution of the present invention: Step 3, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, using a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating, and the electroplating temperature is 24°C-28°C.

[0013] As a further solution of the present invention: Step 3, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, using a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating, and the cathode current density is 10-50ASF.

[0014] As a further solution of the present invention: Step 3, acid copper sulfate copper plating: put the treated substrate into a copper plating tank, use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating, and the forward current time is 10-200ms.

[0015] As a further solution of the present invention: Step 3, acid copper sulfate copper plating: put the treated substrate into a copper plating tank, use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating, and the reverse current time is 0.5-10ms.

[0016] As a further solution of the present invention: Step 3, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, wherein the electroplating solution comprises: 50-90 g / l copper sulfate, 110-140 ml / l sulfuric acid, 50-90 ppm chloride ions, 8-20 ml / l pulse copper plating carrier, and 0.3-0.75 ml / l pulse copper plating brightener.

[0017] As a further solution of the present invention: Step 3, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, wherein the electroplating solution comprises: 50-93 g / l copper sulfate, 110-144 ml / l sulfuric acid, 52-90 ppm chloride ions, 9-20 ml / l pulse copper plating carrier, and 0.3-0.65 ml / l pulse copper plating brightener.

[0018] As a further solution of the present invention: Step 3, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, wherein the electroplating solution comprises: 50-93 g / l copper sulfate, 110-144 ml / l sulfuric acid, 52-90 ppm chloride ions, 9-20 ml / l pulse copper plating carrier, and 0.3-0.65 ml / l pulse copper plating brightener.

[0019] As a further solution of the present invention: Step 3, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, wherein the electroplating solution comprises: 56-90 g / l copper sulfate, 114-140 ml / l sulfuric acid, 50-95 ppm chloride ions, 12-20 ml / l pulse copper plating carrier, and 0.2-0.95 ml / l pulse copper plating brightener.

[0020] As a further solution of the present invention: the pulse copper plating brightener is a sulfonated polyether compound, and the pulse copper plating carrier and brightener need to adjust the concentration and remove organic impurities when added, comprising the following steps: adding 1-2 ml / L of hydrogen peroxide in a cold tank until the copper plating additive is heated to 55°C-65°C; using KI starch test paper to determine whether there is excess hydrogen peroxide in the copper plating additive, and when there is no excess hydrogen peroxide, adding 5 g / L of activated carbon for adsorption; performing a small current electrolysis treatment to remove the hydrogen peroxide remaining in the additive; using a Hall cell to determine and confirm the amount of brightener added and add it, and electrolyzing for 35 minutes.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] A low TOC high-deep plating ability pulse copper plating process is realized. The designed acid copper sulfate copper plating solution and pulse copper plating brightener are used to clean and degrease the substrate, and the acid etching and rust removal are carried out to remove pollutants and oxide layers on the surface of the substrate, so as to improve the adhesion of the plating layer; the surface of the substrate is treated with a surface treatment agent to make it have good electroplating adhesion and facilitate copper deposition; the dried substrate is subjected to external inspection and performance inspection to remove the finished substrate products that are unqualified for copper plating; by adding the designed electroplating solution and process, the frequency of tank replacement and the amount of sewage treatment are reduced, which not only reduces the production cost, but also greatly reduces the pollution to the environment and reduces the production cost of the enterprise; and the additive is treated. The copper plating additive is used to select organic matter with a shorter carbon chain and the same functional group, which can reduce the total carbon content, thereby reducing TOC. Under the same load conditions, the TOC is low, the frequency of tank replacement is reduced, and the wastewater discharge is reduced; at the same time, the low TOC can double the service life of the additive, reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic flow chart of the pulse copper plating process with low TOC and high deep plating capability of the present invention. DETAILED DESCRIPTION

[0024] In one embodiment, Figure 1 As shown, a pulse copper plating process with low TOC and high deep plating capability comprises the following steps:

[0025] Step 1: Pretreatment: Clean and degrease the substrate, and perform acid etching and rust removal to remove pollutants and oxide layers on the substrate surface and improve the adhesion of the coating;

[0026] Step 2: Surface treatment: Use a surface treatment agent to treat the surface of the substrate to make it have good adhesion and facilitate copper deposition;

[0027] Step 3: Acid copper sulfate copper plating: Place the treated substrate into a copper plating tank and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating;

[0028] Step 4: Post-processing: Clean and dry the copper-plated substrate to remove the residual plating solution and impurities on the surface of the substrate;

[0029] Step 5: Inspection: Conduct appearance inspection and performance inspection on the dried substrate to eliminate the finished substrates that fail the copper plating test;

[0030] Step 3: Acid copper sulfate copper plating: Place the treated substrate into a copper plating tank and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating at a temperature of 24°C-28°C;

[0031] Step 3: Acid copper sulfate plating: Place the treated substrate into a copper plating tank and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating. The cathode current density is 10-50 ASF.

[0032] Step 3: Acid copper sulfate plating: Place the treated substrate into a copper plating tank and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating. The forward current time is 10-200ms.

[0033] Step 3: Acid copper sulfate plating: Place the treated substrate into a copper plating tank, and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating, and the reverse current time is 0.5-10ms;

[0034] Group 1: Step 3, acid copper sulfate copper plating: put the treated substrate into a copper plating tank, and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating. The electroplating solution ingredients include: copper sulfate 50-90g / l, sulfuric acid 110-140ml / l, chloride ion 50-90ppm, pulse copper plating carrier 8-20ml / l, pulse copper plating brightener 0.3-0.75ml / l;

[0035] Group 2: Step 3, acid copper sulfate copper plating: put the treated substrate into a copper plating tank, and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating. The electroplating solution includes: copper sulfate 50-92g / l, sulfuric acid 105-145ml / l, chloride ion 55-95ppm, pulse copper plating carrier 8-22ml / l, pulse copper plating brightener 0.3-0.85ml / l;

[0036] Group 3: Step 3, acid copper sulfate copper plating: put the treated substrate into a copper plating tank, and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating. The electroplating solution includes: copper sulfate 50-93g / l, sulfuric acid 110-144ml / l, chloride ion 52-90ppm, pulse copper plating carrier 9-20ml / l, pulse copper plating brightener 0.3-0.65ml / l;

[0037] Group 4: Step 3, acid copper sulfate copper plating: put the treated substrate into a copper plating tank, and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating. The electroplating solution ingredients include: copper sulfate 56-90g / l, sulfuric acid 114-140ml / l, chloride ion 50-95ppm, pulse copper plating carrier 12-20ml / l, pulse copper plating brightener 0.2-0.95ml / l;

[0038] The copper electroplating solutions prepared in the above four groups were added to 1500ml Haring troughs respectively. Clean phosphor copper plates with a phosphorus content of 0.04%-0.065% were placed at both ends of the Haring trough as anodes. The trough was stirred by aerating in the middle with an air stirring speed of 2.5-4L / min.

[0039] After degreasing, microetching, and activation in a dilute sulfuric acid solution, the blind hole plates to be filled (specification 60mm×100mm, blind hole diameter 100μm, hole depth 75μm) were pre-treated and then placed in the liquid of the above-mentioned Haring tank for electroplating (vertically placed in the middle position). During electroplating, the electroplating conditions were: temperature 30°C, current density 1.5A / dm2, and electroplating time 50 minutes.

[0040] The electroplated samples were sectioned and the cross sections of the four groups of samples were observed using a metallographic microscope to evaluate the blind hole filling effect and the surface copper thickness. The results are shown in Table 1.

[0041] Surface copper thickness (micrometer) Brittleness / N Blind hole depression value (micrometer) Hollow Roughness Group 1 19 26 2.3 have Rough Group 2 22 31 1.9 have smooth Group 3 18 26 3.6 none smooth Group 4 23 33 5.2 none smooth

[0042] From the above table, it can be seen that the electroplating effect is best when the electroplating solution is prepared by the fourth group of copper sulfate 56-90g / l, sulfuric acid 114-140ml / l, chloride ion 50-95ppm, pulse copper plating carrier 12-20ml / l, and pulse copper plating brightener 0.2-0.95ml / l.

[0043] Pulse copper plating brightener uses sulfonated polyether compounds or organic phosphonic acid compounds, which have good complexing ability and dispersing properties, can effectively improve the dispersing ability of the plating solution, make the copper ions more evenly distributed on the surface of the workpiece, especially in the deep recesses and complex structural parts of the workpiece, improve the deep plating ability of the plating solution, and at the same time, its low TOC property ensures the purity of the plating solution. And when adding, it is necessary to adjust the concentration and remove organic impurities, including the following steps: add 1-2ml / L of hydrogen peroxide in the cold tank until the copper plating additive is heated to 55℃-65℃; use KI starch test paper to determine whether there is excess hydrogen peroxide in the copper plating additive. If there is no excess hydrogen peroxide, add 5g / L activated carbon for adsorption; perform low current electrolysis to remove the hydrogen peroxide remaining in the additive; use Hall trough to determine the amount of brightener added and add it, and electrolyze for 35 minutes.

[0044] The steps of preparing the electroplating solution include:

[0045] 1. Add 3 / 4 volume of DI water to the copper bath;

[0046] 2. Slowly add the required analytical pure sulfuric acid (continuous stirring is required when adding acid);

[0047] 3. After adding acid, pour copper sulfate into the solution and stir until all copper sulfate is dissolved into the electroplating solution;

[0048] 4. Cool the solution to 24-26℃, add PCP 310M, brightener and analytical pure hydrochloric acid into the electrolytic copper solution;

[0049] 5. Add DI water to the set water level;

[0050] 6. When the bath temperature is in the range of 22-26℃, and the bath composition analysis is within the set control range, use the dragging plate to drag the tank with 5ASF DC for 2 hours, then 10ASF DC for 4 hours, 15ASF DC for 1 hour, 20ASF DC for 1 hour, and finally 20ASF, pulse waveform (F / R=1 / 2 20ms / 1ms) for continuous dragging for 24 hours, and turn on the automatic dosing at the same time. The consumption of light agent and carrier agent is large at the beginning of the tank opening, and it is necessary to follow up and analyze and adjust each shift. After the adjustment is completed, the production board cycle will begin. The chemical materials used in the electroplating solution may bring organic and metal pollution. If the chemical materials used in the tank opening are suspected, they can be purified first. New anode bags, filter cores, and new copper electrolytic tanks need to be soaked in 5% sulfuric acid + 0.5% tank opening agent for 24 hours.

[0051] The above invention realizes a low TOC and high deep plating ability pulse copper plating process, uses the designed acid copper sulfate copper plating solution pulse copper plating brightener to clean and degrease the substrate, and acid etch and remove rust to remove pollutants and oxide layers on the substrate surface and improve the adhesion of the plating layer; uses a surface treatment agent to treat the substrate surface so that it has good electroplating adhesion and is convenient for copper deposition; performs external inspection and performance inspection on the dried substrate to remove the finished substrate products that are unqualified for copper plating; by adding the designed electroplating solution and process, the frequency of tank replacement and the amount of sewage treatment are reduced, which not only reduces the production cost, but also greatly reduces the pollution to the environment and reduces the production cost of the enterprise; and treats the additives, and uses copper plating additives to select organic matter with a shorter carbon chain and the same functional group, which can reduce the total carbon content, thereby achieving TOC reduction. Under the same load conditions, the TOC is low, the frequency of tank replacement is reduced, and the wastewater discharge is reduced; at the same time, low TOC can double the service life of the additive, reducing the production cost.

[0052] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A pulse copper plating process with low TOC and high deep plating capability, characterized in that: The following steps are involved: Step 1: Pretreatment: Clean and degrease the substrate, and perform acid etching and rust removal; Step 2: Surface treatment: Use a treatment agent to treat the surface of the substrate; Step 3: Acid copper sulfate copper plating: Place the treated substrate into a copper plating tank and use a high-purity copper sulfate electroplating solution with a purity of 99.8% for electroplating; Step 4: Post-processing: cleaning and drying the copper-plated substrate; Step 5: Inspection: Perform appearance inspection and performance inspection on the dried substrate.

2. A low TOC high deep plating capability pulse copper plating process according to claim 1, characterized in that: The third step is copper plating with acid copper sulfate: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution having a purity of 99.8%, at a temperature of 24° C.-28° C.

3. A low TOC high deep plating capability pulse copper plating process according to claim 1, characterized in that: The third step is acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, with a cathode current density of 10-50 ASF.

4. A low TOC high deep plating capability pulse copper plating process according to claim 1, characterized in that: The third step is copper plating with acid copper sulfate: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution having a purity of 99.8%, and the forward current time is 10-200ms.

5. A low TOC high deep plating capability pulse copper plating process according to claim 1, characterized in that: The third step is copper plating with acid copper sulfate: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, and the reverse current time is 0.5-10ms.

6. A low TOC high deep plating capability pulse copper plating process according to claim 1, characterized in that: The step three, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, wherein the electroplating solution comprises: 50-90 g / l copper sulfate, 110-140 ml / l sulfuric acid, 50-90 ppm chloride ions, 8-20 ml / l pulse copper plating carrier, and 0.3-0.75 ml / l pulse copper plating brightener.

7. A low TOC high deep plating capability pulse copper plating process according to claim 6, characterized in that: The step three, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, wherein the electroplating solution comprises: 50-92 g / l copper sulfate, 105-145 ml / l sulfuric acid, 55-95 ppm chloride ions, 8-22 ml / l pulse copper plating carrier, and 0.3-0.85 ml / l pulse copper plating brightener.

8. A low TOC high deep plating capability pulse copper plating process according to claim 6, characterized in that: The step three, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, wherein the electroplating solution comprises: 50-93 g / l copper sulfate, 110-144 ml / l sulfuric acid, 52-90 ppm chloride ions, 9-20 ml / l pulse copper plating carrier, and 0.3-0.65 ml / l pulse copper plating brightener.

9. A low TOC high deep plating capability pulse copper plating process according to claim 6, characterized in that: The step three, acid copper sulfate copper plating: placing the treated substrate into a copper plating tank, and electroplating with a high-purity copper sulfate solution with a purity of 99.8%, wherein the electroplating solution comprises: 56-90 g / l copper sulfate, 114-140 ml / l sulfuric acid, 50-95 ppm chloride ions, 12-20 ml / l pulse copper plating carrier, and 0.2-0.95 ml / l pulse copper plating brightener.

10. A low TOC high deep plating capability pulse copper plating process according to claim 6, characterized in that: The pulse copper plating brightener adopts sulfonated polyether compounds, and the concentration needs to be adjusted and organic impurities need to be removed when adding. The method comprises the following steps: adding 1-2 ml / L of hydrogen peroxide in a cold tank until the temperature of the copper plating additive rises to 55° C.-65° C.; using KI starch test paper to determine whether there is excess hydrogen peroxide in the copper plating additive, and when there is no excess hydrogen peroxide, adding 5 g / L of activated carbon for adsorption; performing low current electrolysis treatment to remove the hydrogen peroxide remaining in the additive; using Hall cell measurement to confirm the amount of brightener added and adding it, and electrolyzing for 35 minutes.

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