A method for reducing solder etch copper residue on amb copper clad ceramic substrates
By employing a dual etching process involving short-duration, multiple immersions in solder etchant and copper etching solution, the problem of copper residue in AMB copper-clad ceramic substrate solder etching was solved, achieving effective removal of copper residue and improved substrate stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2026-03-24
AI Technical Summary
In the existing AMB process, copper residue is easily generated during the solder etching process of AMB copper-clad ceramic substrates, which leads to reduced solder etching yield and high voltage short circuit risk. Traditional etching solutions are difficult to effectively remove copper residue located at the interface between the bottom of the solder layer and the ceramic.
A dual etching process is adopted, which combines short-time, multiple immersion solder etching solution with copper etching solution. The solder etching solution uses amino polycarboxylic acid compounds, thiadiazole compounds and surfactants, while the copper etching solution uses an acidic system composed of sulfuric acid, phosphoric acid, citric acid and imidazole compounds. This improves etching efficiency and selectivity during both solder etching and copper etching processes, and cleans copper residues.
It significantly reduces copper residue on the surface of AMB substrates, improves the uniformity and selectivity of solder etching, enhances substrate stability, avoids leakage current between copper islands, and extends substrate lifespan.
Smart Images
Figure CN120857364B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of copper-clad ceramic substrate manufacturing, and particularly relates to a method for reducing copper residue of solder etching of AMB copper-clad ceramic substrate. BACKGROUND
[0002] With the vigorous development of new energy vehicles, photovoltaic and high-power electronic module industries, the requirements for high-power devices are more stringent, and the market demand is also increasing. At present, in high-power devices, ceramic substrates are combined with copper foils to form copper-clad substrates. AMB copper-clad ceramic substrates have the advantages of high interfacial bonding strength, long thermal cycle life, high heat dissipation efficiency, and strong current carrying capacity, which makes them gradually become the core material for packaging high-power devices in the field of high-power density (such as silicon carbide module packaging).
[0003] Ag-Cu-Ti brazing paste is the most commonly used solder in AMB process, which has good fluidity, ceramic wettability, easy operability and low brazing temperature, and is favored by many manufacturers. However, during the cooling process of silver-copper eutectic liquid, the gradual crystallization of the eutectic structure with alternating distribution of silver and copper after brazing makes the metal distribution more complex, especially at the junction of the brazing layer and the ceramic. The copper is not completely wrapped by silver. The traditional AMB process uses solder etching liquid, which cannot obviously etch this type of copper, so the part of copper that is not completely wrapped by silver cannot be quickly stripped and fallen off during the solder etching process, resulting in copper residue on the patterned AMB substrate during the solder etching process. The copper remaining on the AMB substrate not only reduces the yield of solder etching, but also increases the leakage current between copper islands, making the AMB substrate face the risk of high-voltage short circuit. Therefore, it is urgent to develop a new AMB process to reduce the copper residue on the surface of the AMB substrate.
[0004] Therefore, it is of great significance to invent a method for reducing copper residue of solder etching of AMB copper-clad ceramic substrate. SUMMARY
[0005] The purpose of the present application is to provide a method for reducing copper residue of solder etching of AMB copper-clad ceramic substrate to solve the problems in the prior art.
[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme:
[0007] A method for reducing copper residue of solder etching of AMB copper-clad ceramic substrate, comprising the following steps:
[0008] S1: placing the AMB substrate in the solder etching liquid, stirring and soaking for 5-15 min to obtain a solder etching AMB substrate;
[0009] S2: washing the solder etching AMB substrate with water, taking out and drying, then placing in a copper etching solution, constant temperature immersion for 30-60s, washing with water again and drying, to obtain a copper etching AMB substrate;
[0010] S3: repeating S1 and S2 for 3-5 times of solder etching, cleaning the product through a cleaning line and drying, to obtain an AMB copper clad ceramic substrate;
[0011] Further, in step S1, the solder etching solution is prepared as follows: slowly adding sulfuric acid into deionized water, stirring and cooling, adding an amino polycarboxylic acid compound, stirring for 5-15 min, sequentially adding a thiadiazole compound, dodecyl dimethyl betaine, stirring and mixing, then adding ammonium persulfate, stirring and mixing, to obtain the solder etching solution.
[0012] Further, in step S1, the solder etching solution is prepared as follows: slowly adding sulfuric acid into deionized water, stirring and cooling, adding an amino polycarboxylic acid compound, stirring for 5-15 min, sequentially adding a thiadiazole compound, dodecyl dimethyl betaine, stirring and mixing, then adding ammonium persulfate, stirring and mixing, to obtain the solder etching solution.
[0013] Further, in step S1, the solder etching solution is prepared as follows: slowly adding sulfuric acid into deionized water, stirring and cooling, adding an amino polycarboxylic acid compound, stirring for 5-15 min, sequentially adding a thiadiazole compound, dodecyl dimethyl betaine, stirring and mixing, then adding ammonium persulfate, stirring and mixing, to obtain the solder etching solution.
[0014] Further, in step S1, the solder etching solution is prepared as follows: slowly adding sulfuric acid into deionized water, stirring and cooling, adding an amino polycarboxylic acid compound, stirring for 5-15 min, sequentially adding a thiadiazole compound, dodecyl dimethyl betaine, stirring and mixing, then adding ammonium persulfate, stirring and mixing, to obtain the solder etching solution.
[0015] Further, in step S2, the copper etching solution is prepared as follows: slowly adding concentrated sulfuric acid into deionized water, stirring and cooling, then sequentially adding copper sulfate, phosphoric acid and citric acid, stirring and mixing, then adding ethylenediaminetetramethylene phosphonic acid, 2-mercaptobenzoxazole, an imidazole compound, phytic acid and cetyltrimethylammonium bromide, stirring until the solution is clear, finally slowly adding hydrogen peroxide, stirring, to obtain the copper etching solution.
[0016] Further, in step S2, the copper etching solution is prepared as follows: slowly adding concentrated sulfuric acid into deionized water, stirring and cooling, then sequentially adding copper sulfate, phosphoric acid and citric acid, stirring and mixing, then adding ethylenediaminetetramethylene phosphonic acid, 2-mercaptobenzoxazole, an imidazole compound, phytic acid and cetyltrimethylammonium bromide, stirring until the solution is clear, finally slowly adding hydrogen peroxide, stirring, to obtain the copper etching solution.
[0017] Further, in step S2, the imidazole compound is one or more of imidazole, 4-methylimidazolium, 1-phenyl-4-methylimidazolium, 4-methyl-5-hydroxymethylimidazolium, 2-hexylbenzoimidazolium, 1-butyl-3-methylimidazolium acetate, 1-octyl-3-methylimidazolium L-lactate, 1-octyl-3-methylimidazolium acetate, and 1-octyl-3-methylimidazolium L-tartrate.
[0018] Compared with the prior art, the beneficial effects of the present invention are:
[0019] 1. This invention elucidates the mechanism of copper residue generation in AMB copper-clad ceramic substrates prepared with Ag-Cu-Ti solder paste. During the process of forming a copper-silver eutectic phase through soldering at the solder interface, silver-based solid solutions (referred to as silver regions) and copper-based solid solutions (referred to as copper regions) will appear. The copper regions mainly exist in two forms: (1) Most copper regions are located inside the solder layer and are completely encapsulated by the silver regions. These copper regions will fall off during the solder etching process as the surrounding silver regions peel off, without causing copper residue on the AMB substrate; (2) A small portion of copper regions are located at the junction of the solder layer and the ceramic. These copper regions are not completely encapsulated by the silver regions and cannot fall off during the etching process as the surrounding silver regions peel off. They can only fall off after the extremely thin reaction layer at the bottom is completely etched. However, the traditional AMB etching process conditions are difficult to achieve the etching effect in a short time, resulting in these copper regions being easily retained after solder etching, forming dot-like copper residue. Based on the principle of copper residue on the surface of AMB substrates, this invention employs a short-time, multiple-immersion etching method with solder etchant on AMB substrates prepared with Ag-Cu-Ti solder paste. This process removes the silver-copper eutectic phase from the etched area within the solder layer and promotes the removal of the silver region at the junction of the solder layer and ceramic, exposing the copper residue at this junction. This facilitates subsequent cleaning of the copper residue with a copper etching solution. After each solder etch, the water-washed AMB substrate is etched with a copper etching solution to promptly clean the exposed copper residue, thereby reducing copper residue on the AMB substrate.
[0020] 2. The solder etching solution of this invention, under the strongly acidic environment provided by sulfuric acid, allows persulfate ions to convert silver and titanium into silver and titanium ions, causing amino acid salts to complex with silver and titanium ions, forming stable water-soluble complexes. This prevents the hydrolysis of silver and titanium ions to form precipitates, improving etching speed and uniformity, avoiding incomplete etching, and reducing copper residue on the AMB substrate. The heterocyclic framework of thiadiazole compounds contains sulfur and nitrogen heteroatoms, which can form coordination bonds, and their thiol and amino functional groups can covalently or coordinate with silver, providing good corrosion inhibition for silver and improving the etching efficiency of the etching solution. The amphoteric surfactant dodecyl dimethyl betaine reduces the surface tension of the solder etching solution, allowing it to be uniformly dispersed on the AMB substrate surface, promoting the stripping of silver areas in the AMB substrate etching region, and avoiding incomplete silver etching.
[0021] 3. In the copper etching solution described in this invention, the acidic system composed of sulfuric acid, phosphoric acid, and citric acid not only maintains the pH stability of the etching solution and reduces hydrogen peroxide loss, but also promotes the oxidation of copper atoms on the AMB substrate to copper ions by hydrogen peroxide. This helps ethylenediaminetetramethylenephosphonic acid preferentially form a stable water-soluble complex with copper ions, preventing copper ions from undergoing a displacement reaction with silver on the AMB copper-clad ceramic substrate, and improving the etching ability of the etching solution to remove residual copper on the AMB substrate. Simultaneously, citric acid, phytic acid, and ethylenediaminetetramethylenephosphonic acid synergistically complex copper ions, preventing copper ion precipitation and catalyzing hydrogen peroxide decomposition, thereby increasing the etching rate and maintaining the stability of the etching solution. 2-Mercaptobenzothiazole and imidazole compounds form a protective film on the sidewalls and copper surface of the AMB substrate, synergistically inhibiting side etching on the AMB substrate and enhancing the stability of the AMB copper-clad ceramic substrate. The phosphoric hydroxyl groups on phytic acid can capture free hydroxyl radicals, alleviating the loss of hydrogen peroxide by hydroxyl radicals, thus reducing the loss of hydrogen peroxide in the etching solution. Hexadecyltrimethylammonium bromide is a cationic surfactant that can significantly reduce the surface tension of the copper etching solution, promote the penetration of the copper etching solution into the micro-gaps between the ceramic and the AgCuTi brazing layer, and reduce copper residue on the AMB substrate. Attached Figure Description
[0022] Figure 1 This is a SEM image of the copper region inside the brazing interface in Embodiment 1 of the present invention;
[0023] Figure 2 This is a SEM image of the dotted copper area at the ceramic tile brazing interface in Example 1 of this invention.
[0024] Figure 3 This is a solder etching process step in the present invention to reduce copper residue;
[0025] Figure 4 This is a microscope image of the gaps between copper islands after solder etching in Example 1 of this invention;
[0026] Figure 5 This is a microscope image of the gaps between copper islands after conventional solder etching in Comparative Example 3 of this invention. Detailed Implementation
[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0028] The CAS number for ethylenediaminetetraacetic acid is 60-00-4; the CAS number for 2-mercapto-5-methyl-1,3,4-thiadiazole is 29490-19-5; the CAS number for dodecyl dimethyl betaine is 683-10-3; the CAS number for citric acid is 77-92-9; the CAS number for ethylenediaminetetramethylenephosphonic acid is 1429-50-1; the CAS number for 2-mercaptobenzoxazole is 2382-96-9; the CAS number for 2-methylimidazole is 693-98-1; the CAS number for phytic acid is 83-86-3; the CAS number for hexadecyltrimethylammonium bromide is 57-09-0; and the CAS number for ammonium persulfate is 7727-54-0.
[0029] Example 1: A method for reducing residual copper in solder etching on AMB copper-clad ceramic substrates: S1: Slowly add 80g of sulfuric acid to 1L of deionized water, stir and cool, add 10g of ethylenediaminetetraacetic acid, stir for 10min, then add 0.5g of 2-mercapto-5-methyl-1,3,4-thiadiazole and 0.1g of dodecyl dimethyl betaine in sequence, stir and mix well, then add 50g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0030] S2: Place the AMB substrate into the solder etching solution, stir and soak for 5 minutes to obtain the solder-etched AMB substrate.
[0031] S3: Slowly add 80g of sulfuric acid to 1L of deionized water, stir and cool. Then add 1g of copper sulfate, 0.5g of phosphoric acid and 1g of citric acid in sequence, stir and mix well. Then add 10g of ethylenediaminetetramethylenephosphonic acid, 0.1g of 2-mercaptobenzoxazole, 1g of 2-methylimidazole, 5g of phytic acid and 0.1g of hexadecyltrimethylammonium bromide, stir until the solution is clear, and finally slowly add 70mL of hydrogen peroxide and stir to obtain copper etching solution.
[0032] S4: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature of 35°C for 30 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate.
[0033] S5: Repeat S2 and S4, and after four solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0034] Example 2: A method for reducing residual copper in solder etching on AMB copper-clad ceramic substrates: S1: Slowly add 100g of sulfuric acid to 1L of deionized water, stir and cool, add 15g of ethylenediaminetetraacetic acid, stir for 10min, then add 1.2g of 2-mercapto-5-methyl-1,3,4-thiadiazole and 0.5g of dodecyl dimethyl betaine in sequence, stir and mix well, then add 100g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0035] S2: Place the AMB substrate into the solder etching solution, stir and soak for 5 minutes to obtain the solder-etched AMB substrate.
[0036] S3: Slowly add 80g of sulfuric acid to 1L of deionized water, stir and cool. Then add 1g of copper sulfate, 0.5g of phosphoric acid and 1g of citric acid in sequence, stir and mix well. Then add 10g of ethylenediaminetetramethylenephosphonic acid, 0.1g of 2-mercaptobenzoxazole, 1g of 2-methylimidazole, 5g of phytic acid and 0.1g of hexadecyltrimethylammonium bromide, stir until the solution is clear, and finally slowly add 70mL of hydrogen peroxide and stir to obtain copper etching solution.
[0037] S4: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature of 35°C for 30 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate.
[0038] S5: Repeat S2 and S4, and after three solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0039] Example 3: A method for reducing residual copper in solder etching on AMB copper-clad ceramic substrates: S1: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool, add 20g of ethylenediaminetetraacetic acid, stir for 10min, then add 2g of 2-mercapto-5-methyl-1,3,4-thiadiazole and 1g of dodecyl dimethyl betaine in sequence, stir and mix well, then add 150g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0040] S2: Place the AMB substrate into the solder etching solution, stir and soak for 5 minutes to obtain the solder-etched AMB substrate.
[0041] S3: Slowly add 80g of sulfuric acid to 1L of deionized water, stir and cool. Then add 1g of copper sulfate, 0.5g of phosphoric acid and 1g of citric acid in sequence, stir and mix well. Then add 10g of ethylenediaminetetramethylenephosphonic acid, 0.1g of 2-mercaptobenzoxazole, 1g of 2-methylimidazole, 5g of phytic acid and 0.1g of hexadecyltrimethylammonium bromide, stir until the solution is clear, and finally slowly add 70mL of hydrogen peroxide and stir to obtain copper etching solution.
[0042] S4: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature of 35°C for 30 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate.
[0043] S5: Repeat S2 and S4, and after three solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0044] Example 4: A method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates: S1: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool, add 20g of ethylenediaminetetraacetic acid, stir for 10min, add 2g of 2-mercapto-5-methyl-1,3,4-thiadiazole and 1g of dodecyl dimethyl betaine in sequence, stir and mix well, then add 150g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0045] S2: Place the AMB substrate into the solder etching solution, stir and soak for 10 minutes to obtain the solder-etched AMB substrate.
[0046] S3: Slowly add 80g of sulfuric acid to 1L of deionized water, stir and cool. Then add 1g of copper sulfate, 0.5g of phosphoric acid and 1g of citric acid in sequence, stir and mix well. Then add 10g of ethylenediaminetetramethylenephosphonic acid, 0.1g of 2-mercaptobenzoxazole, 1g of 2-methylimidazole, 5g of phytic acid and 0.1g of hexadecyltrimethylammonium bromide, stir until the solution is clear, and finally slowly add 70mL of hydrogen peroxide and stir to obtain copper etching solution.
[0047] S4: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature of 35°C for 30 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate.
[0048] S5: Repeat S2 and S4, and after three solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0049] Example 5: A method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates: S1: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool, add 20g of ethylenediaminetetraacetic acid, stir for 10min, add 2g of 2-mercapto-5-methyl-1,3,4-thiadiazole and 1g of dodecyl dimethyl betaine in sequence, stir and mix well, then add 150g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0050] S2: Place the AMB substrate into the solder etching solution, stir and soak for 15 minutes to obtain the solder-etched AMB substrate.
[0051] S3: Slowly add 80g of sulfuric acid to 1L of deionized water, stir and cool. Then add 1g of copper sulfate, 0.5g of phosphoric acid and 1g of citric acid in sequence, stir and mix well. Then add 10g of ethylenediaminetetramethylenephosphonic acid, 0.1g of 2-mercaptobenzoxazole, 1g of 2-methylimidazole, 5g of phytic acid and 0.1g of hexadecyltrimethylammonium bromide, stir until the solution is clear, and finally slowly add 70mL of hydrogen peroxide and stir to obtain copper etching solution.
[0052] S4: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature of 35°C for 30 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate.
[0053] S5: Repeat S2 and S4, and after three solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0054] Example 6: A method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates: S1: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool, add 20g of ethylenediaminetetraacetic acid, stir for 10min, add 2g of 2-mercapto-5-methyl-1,3,4-thiadiazole and 1g of dodecyl dimethyl betaine in sequence, stir and mix well, then add 150g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0055] S2: Place the AMB substrate into the solder etching solution, stir and soak for 15 minutes to obtain the solder-etched AMB substrate.
[0056] S3: Slowly add 100g of sulfuric acid to 1L of deionized water, stir and cool. Then add 8g of copper sulfate, 1.2g of phosphoric acid and 5g of citric acid in sequence, stir and mix well. Then add 30g of ethylenediaminetetramethylenephosphonic acid, 1g of 2-mercaptobenzoxazole, 3g of 2-methylimidazole, 12g of phytic acid and 0.5g of cetyltrimethylammonium bromide, stir until the solution is clear, and finally slowly add 85mL of hydrogen peroxide and stir to obtain copper etching solution.
[0057] S4: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature of 35°C for 45 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate.
[0058] S5: Repeat S2 and S4, and after four solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0059] Example 7: A method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates: S1: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool, add 20g of ethylenediaminetetraacetic acid, stir for 10min, add 2g of 2-mercapto-5-methyl-1,3,4-thiadiazole and 1g of dodecyl dimethyl betaine in sequence, stir and mix well, then add 150g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0060] S2: Place the AMB substrate into the solder etching solution, stir and soak for 15 minutes to obtain the solder-etched AMB substrate.
[0061] S3: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool. Then add 15g of copper sulfate, 2g of phosphoric acid and 10g of citric acid in sequence, stir and mix well. Then add 30g of ethylenediaminetetramethylenephosphonic acid, 1.5g of 2-mercaptobenzoxazole, 5g of 2-methylimidazole, 20g of phytic acid and 0.1g of hexadecyltrimethylammonium bromide, stir until the solution is clear, and finally slowly add 100mL of hydrogen peroxide and stir to obtain copper etching solution.
[0062] S4: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature of 35°C for 60 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate.
[0063] S5: Repeat S2 and S4, and after 5 solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0064] Comparative Example 1: A method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates: S1: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool, add 20g of ethylenediaminetetraacetic acid, stir for 10min, add 2g of 2-mercapto-5-methyl-1,3,4-thiadiazole, stir and mix well, then add 150g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0065] S2: Place the AMB substrate into the solder etching solution, stir and soak for 15 minutes to obtain the solder-etched AMB substrate.
[0066] S3: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool. Then add 15g of copper sulfate, 2g of phosphoric acid and 10g of citric acid in sequence, stir and mix well. Then add 30g of ethylenediaminetetramethylenephosphonic acid, 1.5g of 2-mercaptobenzoxazole, 5g of 2-methylimidazole, 20g of phytic acid and 0.1g of hexadecyltrimethylammonium bromide, stir until the solution is clear, and finally slowly add 100mL of hydrogen peroxide and stir to obtain copper etching solution.
[0067] S4: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature of 35°C for 60 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate.
[0068] S5: Repeat S2 and S4, and after 5 solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0069] Comparative Example 2: A method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates: S1: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool, add 20g of ethylenediaminetetraacetic acid, stir for 10min, add 2g of 2-mercapto-5-methyl-1,3,4-thiadiazole and 1g of dodecyl dimethyl betaine in sequence, stir and mix well, then add 150g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0070] S2: Place the AMB substrate into the solder etching solution, stir and soak for 15 minutes to obtain the solder-etched AMB substrate.
[0071] S3: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool. Then add 15g of copper sulfate, 2g of phosphoric acid and 10g of citric acid in sequence, stir and mix well. Then add 1.5g of 2-mercaptobenzoxazole, 5g of 2-methylimidazole and 0.1g of hexadecyltrimethylammonium bromide, stir until the solution is clear, and finally slowly add 100mL of hydrogen peroxide and stir to obtain copper etching solution.
[0072] S4: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature of 35°C for 60 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate.
[0073] S5: Repeat S2 and S4, and after 5 solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0074] Comparative Example 3: A method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates: S1: Slowly add 120g of sulfuric acid to 1L of deionized water, stir and cool, add 20g of ethylenediaminetetraacetic acid, stir for 10min, add 2g of 2-mercapto-5-methyl-1,3,4-thiadiazole and 1g of dodecyl dimethyl betaine in sequence, stir and mix well, then add 150g of ammonium persulfate, stir and mix well to obtain solder etching solution;
[0075] S2: Place the AMB substrate into the solder etching solution, stir and soak for 15 minutes to obtain the solder-etched AMB substrate.
[0076] S3: The solder-etched AMB substrate is washed with water, dried, acid-washed, washed and dried again to obtain the etched AMB substrate.
[0077] S5: Repeat S2 and S4, after two solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate.
[0078] Testing and Inspection
[0079] Etching effect measurement: The etching effect of the AMB substrates treated in the examples and comparative examples was observed using an electron microscope (SEM).
[0080] The etching effect is divided into four levels: Excellent - no copper residue observed; Good - very little copper residue observed; Medium - a small amount of copper residue observed; Poor - a large amount of residue observed.
[0081] The experimental results are shown in Table 1 below.
[0082] Table 1 Performance test data of AMB substrates made with AgCuTi solder paste
[0083] Etching effect Example 1 Good Example 2 Good Example 3 Good Example 4 Excellent Example 5 Excellent Example 6 Excellent Example 7 Excellent Comparative Example 1 Fair Comparative Example 2 Fair Comparative Example 3 Poor
[0084] Conclusion: Cleaning the AMB substrate with copper etchant after solder etching can significantly reduce copper residue on the AMB substrate surface.
[0085] Comparative Example 1: The absence of dodecyl dimethyl betaine as an amphoteric surfactant in the solder etch solution reduced the dispersibility of the solder etch solution on the surface of the AMB substrate, resulting in incomplete removal of silver areas on the etched areas of the AMB substrate, especially the silver areas located at the interface between the solder layer and the ceramic layer. This, in turn, reduced the etching yield of copper areas on the AMB substrate that were not completely covered by silver areas, ultimately leading to an increase in copper residue on the AMB substrate.
[0086] Comparative Example 2: The absence of ethylenediaminetetramethylenephosphonic acid (EDTA) and phytic acid in the copper etching solution reduced its ability to complex copper ions, decreasing the etching rate and leading to an increase in copper residue in the AMB substrate. The lack of EDTA also prevented the substitution reaction between copper ions and silver in the etching solution, further reducing the etching rate. Furthermore, the lack of phytic acid increased the ineffective decomposition of hydrogen peroxide, increasing hydrogen peroxide loss in the etching solution.
[0087] Comparative Example 3: The AMB substrate was routinely acid-washed after solder etching, but no copper etching solution was used for secondary etching. This resulted in a high amount of residual copper in the area between the solder layer and the ceramic that was not completely covered by silver, which affected the service life of the AMB substrate.
[0088] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A method for reducing copper residue left in solder etching on AMB copper-clad ceramic substrates, characterized in that: Includes the following steps: S1: Place the AMB substrate into the solder etching solution, stir and soak for 5-15 minutes to obtain the solder-etched AMB substrate; S2: Wash the solder-etched AMB substrate with water, take it out and dry it, then place it in the copper etching solution and immerse it at a constant temperature for 30-60 seconds. Wash it with water and dry it again to obtain the copper-etched AMB substrate. S3: Repeat S1 and S2, and after 3-5 solder etchings, clean the product through the cleaning line and dry it to obtain the AMB copper-clad ceramic substrate. The solder etching solution comprises the following components: ammonium persulfate, sulfuric acid, aminopolycarboxylic acid compounds, thiadiazole compounds, dodecyl dimethyl betaine, and deionized water; The copper etching solution comprises the following components: hydrogen peroxide, sulfuric acid, copper sulfate, citric acid, phosphoric acid, phytic acid, imidazole compounds, 2-mercaptobenzoxazole, ethylenediaminetetramethylenephosphonic acid, hexadecyltrimethylammonium bromide, and deionized water. The preparation method of the solder etching solution is as follows: Sulfuric acid is slowly added to deionized water, stirred and cooled, amino polycarboxylic acid compound is added, stirred for 5-15 minutes, thiadiazole compound and dodecyl dimethyl betaine are added in sequence, stirred and mixed, and then ammonium persulfate is added and stirred and mixed to obtain solder etching solution. The preparation method of the copper etching solution is as follows: Sulfuric acid is slowly added to deionized water, stirred and cooled, then copper sulfate, phosphoric acid and citric acid are added in sequence, stirred and mixed, then ethylenediaminetetramethylenephosphonic acid, 2-mercaptobenzoxazole, imidazole compounds, phytic acid and hexadecyltrimethylammonium bromide are added, stirred until the solution is clear, and finally hydrogen peroxide is slowly added and stirred to obtain the copper etching solution. The solder used in the preparation of the AMB substrate is Ag-Cu-Ti solder paste.
2. The method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates according to claim 1, characterized in that: In step S1, the amounts of each component added to the solder etching solution are: ammonium persulfate 50-150 g / L, sulfuric acid 80-120 g / L, amino polycarboxylic acid compound 10-20 g / L, thiadiazole compound 0.5-2 g / L, and dodecyl dimethyl betaine 0.1-1 g / L.
3. The method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates according to claim 1, characterized in that: In step S1, the aminopolycarboxylic acid compound includes one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, N-hydroxyethylethylenediaminetriacetic acid, hypozoxytriacetic acid, (S,S)-ethylenediamine-N,N′-disuccinic acid, methylglycine diacetic acid, and glutamic acid diacetic acid.
4. The method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates according to claim 1, characterized in that: In step S1, the thiadiazole compound includes one or more of 2,5-dimercaptothiadiazole, 2-mercapto-5-methyl-1,3,4-thiadiazole, 2,5-diamino-1,3,4-thiadiazole, and 2,5-diphenyl-1,3,4-thiadiazole.
5. The method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates according to claim 1, characterized in that: In step S2, the amounts of each component added to the copper etching solution are as follows: hydrogen peroxide 70-100 mL / L, sulfuric acid 80-120 g / L, copper sulfate 1-15 g / L, citric acid 1-10 g / L, phosphoric acid 0.5-2 g / L, phytic acid 5-20 g / L, imidazole compounds 1-5 g / L, 2-mercaptobenzoxazole 0.1-1.5 g / L, ethylenediaminetetramethylenephosphonic acid 10-30 g / L, and hexadecyltrimethylammonium bromide 0.1-1 g / L.
6. The method for reducing copper residue in solder etching of AMB copper-clad ceramic substrates according to claim 1, characterized in that: In step S2, the imidazole compound is one or more of imidazole, 4-methylimidazolium, 1-phenyl-4-methylimidazolium, 4-methyl-5-hydroxymethylimidazolium, 2-hexylbenzoimidazolium, 1-butyl-3-methylimidazolium acetate, 1-octyl-3-methylimidazolium L-lactate, 1-octyl-3-methylimidazolium acetate, and 1-octyl-3-methylimidazolium L-tartrate.
Citation Information
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