A copper-aluminum foil production method for avoiding soldering flux and improving tin coating rate

Abstract

The application discloses a copper-aluminum foil production method for avoiding soldering flux and improving tin coating rate, which comprises the following steps: copper-aluminum foil rolling; alkali washing; acid washing; glue coating; tin coating; and surface low-temperature finishing. In the application, the existing electrolytic copper foil is replaced by copper-aluminum composite strip T2-8011, the roughness of copper and aluminum surfaces is controlled through polishing and foil rolling, the surface roughness is further improved through alkali washing and acid washing, the surface oxidation and residual oil spots are treated, the glue coating amount is improved, the tin coating amount is improved, the surface adhesion is improved through surface low-temperature finishing, the tin coating amount is improved, there is no tin dropping phenomenon, the problems of low tin coating rate, tin dropping and the need of using chemical soldering flux on the surface of the traditional electrolytic copper foil are solved, and more superior alloy materials are provided for the field of conductive, heat-dissipating and light-weight foil materials, and can be widely applied to working electronic conductive, heat-dissipating sheets, photovoltaic power generation, electronic light beam tubes, LED lamp strips and other products.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tin plating on copper-aluminum foil, and particularly relates to a copper-aluminum foil production method for avoiding flux and improving tin plating rate. BACKGROUND

[0002] In the traditional process, tin plating on the surface of electrolytic copper foil is prone to the problems of tin plating hanging or tin plating rate being particularly low. Through multiple experimental analyses, it is found that the main reason is that the oxides and oil spots on the surface of the copper foil are not cleaned. To solve such problems, the common practice at present is to apply a strong acid flux prepared by mixing zinc chloride and hydrochloric acid on the surface of the electrolytic copper foil, but the final tin plating rate can only reach 70%. SUMMARY

[0003] To solve the technical problems in the prior art, the purpose of the present application is to provide a copper-aluminum foil production method for avoiding flux and improving tin plating rate.

[0004] To achieve the above purposes and achieve the above technical effects, the technical solution adopted by the present application is as follows:

[0005] A copper-aluminum foil production method for avoiding flux and improving tin plating rate, comprising the following steps:

[0006] 1) Copper-aluminum foil rolling:

[0007] Selecting a copper-aluminum composite strip, polishing and rolling the copper-aluminum composite strip;

[0008] 2) Alkaline cleaning;

[0009] 3) Acid pickling;

[0010] 4) Gluing;

[0011] 5) Tin plating;

[0012] 6) Surface low-temperature finishing.

[0013] Further, in step 1), the copper-aluminum composite strip is a copper-aluminum composite strip T2-8011, the front surface material of which is T2 red copper, and the back surface material of which is 8011 alloy aluminum, and the percentage of copper and aluminum is 20% and 80%, respectively.

[0014] The copper-aluminum composite strip is rolled to 0.035-0.060 mm, the strip width is 800-1020 mm, the thickness tolerance is ±1 μm, the copper surface roughness Ra is 0.3-0.6 μm, the aluminum surface roughness Ra is less than or equal to 0.5 μm, and the surface Darcy value is less than 42#.

[0015] Further, in step 2), the step of alkaline cleaning comprises:

[0016] The copper-aluminum composite strip obtained in step 1) is placed in a soaking tank, and is subjected to alkaline cleaning using an organic alkali, the concentration of the organic alkali is controlled to be 10-15%, the heating temperature is controlled to be 50-70°C, and the alkaline cleaning speed is controlled to be 5-15 m / min, and after the alkaline cleaning, the surface durometer is less than 36#, and after the cleaning, the copper-aluminum composite strip is cleaned 2-5 times using deionized water.

[0017] Further, in step 3), the step of acid cleaning comprises:

[0018] The copper-aluminum composite strip obtained in step 2) is placed in a soaking tank, and is subjected to soaking cleaning using dilute sulfuric acid and sodium persulfate, the speed is controlled to be 5-20 m / min, the concentration of the dilute sulfuric acid and sodium persulfate is controlled to be 2-5%, and the mass ratio is 1:1, and after the cleaning, the copper-aluminum composite strip is cleaned 2-5 times using deionized water.

[0019] Subsequently, the copper-aluminum composite strip is placed in another soaking tank, and is subjected to soaking cleaning using dilute sulfuric acid, the concentration of the dilute sulfuric acid is controlled to be 2-5%, the acid cleaning speed is controlled to be 5-15 m / min, and after the cleaning, the copper-aluminum composite strip is cleaned 2-5 times using deionized water, and is dried for standby.

[0020] Further, in step 4), the step of gluing comprises:

[0021] A special adhesive is uniformly coated on the surface of the copper-aluminum composite strip obtained in step 3) by screen printing, and is preheated, and the temperature is controlled to be 135-165°C.

[0022] Further, the preparation raw materials of the special adhesive comprise the following components in the following weight fractions:

[0023] Polyimide modified phenolic resin 10-20 parts

[0024] Boron nitride 5-10 parts

[0025] Silane coupling agent 4-10 parts

[0026] Cerium dioxide 2-6 parts

[0027] Curing agent 3-8 parts

[0028] The boron nitride is prepared by mixing spherical boron nitride and irregular boron nitride according to a weight ratio of 1-2:1-3, the spherical boron nitride is prepared by mixing spherical boron nitride with a particle size of 3.5-5 μm and spherical boron nitride with a particle size of 0.3-1.5 μm according to a weight ratio of 1:2, and the irregular boron nitride is prepared by mixing irregular boron nitride with a particle size of 2-6 μm and irregular boron nitride with a particle size of 0.1-1.0 μm according to a weight ratio of 1:2.

[0029] Furthermore, the special adhesive is prepared using the following steps:

[0030] 1) Preparation of polyimide-modified phenolic resin:

[0031] At 95-98℃, polyimide and phenolic resin are stirred and mixed at a weight ratio of 1:1.5. Then, imidazole or polyamide curing agent is added, and the mixture is stirred and mixed to obtain the desired polyimide-modified phenolic resin.

[0032] 2) Mix 10-20 parts of polyimide-modified phenolic resin, 5-10 parts of boron nitride, and half of the silane coupling agent. Stir at 90-95℃ for 20-50 minutes, and control the vacuum at 0.08-0.11 MPa. Then, add 2-6 parts of cerium dioxide and continue stirring. Add the other half of the silane coupling agent and continue stirring. Finally, add 3-8 parts of curing agent and stir until well mixed to obtain the desired special adhesive.

[0033] Furthermore, in step 5), the tinning process includes:

[0034] On the surface of the copper-aluminum composite strip obtained in step 4), a tin layer is formed by vacuum sputtering. The following conditions must be met: sputtering voltage controlled at 400-450V, sputtering current controlled at 0.2-0.4A, and vacuum degree controlled at (3.3-3.8)×10⁻⁶. - 3 Pa, the tin deposition rate is controlled at 145-155 nm / min.

[0035] Furthermore, in step 5), the tinning process includes:

[0036] The copper-aluminum composite strip obtained in step 4) is fed into a soldering furnace for tinning. The tinning process is immersion-type, with a furnace length of 1.5m. Resistance wire heating is used, with the temperature controlled at 260-265℃, a tinning speed of 5-15m / min, and strip tension controlled at 0.2kg / mm. 2 Tinning time is 6-18 seconds.

[0037] Furthermore, in step 6), the low-temperature surface finishing step includes:

[0038] The product obtained in step 5) is passed through a finishing roller to smooth the surface tin. The speed is controlled at 5-15 m / min, the surface roughness Ra of the finishing roller is ≤0.2 μm, the finishing force is 2-3 kg / mm, and the roller surface temperature is controlled at 130-185℃. At this temperature, the surface tin is in a semi-molten state, which makes the tin on the strip surface uniform, delicate and smooth, enhances the surface adhesion, and prevents the surface tin from falling off. The thickness of the obtained tin layer reaches 30-100 μm, the distribution is uniform, and the tin application rate reaches 75-93%.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] This invention discloses a method for producing copper-aluminum foil that avoids flux and improves tinning rate, comprising the following steps: 1) Copper-aluminum foil rolling: Selecting copper-aluminum composite strip, grinding and rolling it; 2) Alkali washing; 3) Acid washing; 4) Coating with adhesive; 5) Tinning; 6) Low-temperature surface finishing. In this invention, copper-aluminum composite strip T2-8011 is used to replace the existing electrolytic copper foil. The roughness of the copper and aluminum surfaces is controlled by grinding and foil rolling. Alkali washing and acid washing help to further improve the surface roughness, while also helping to deal with oxidation and residual oil spots on the strip surface, increasing the amount of adhesive coating, and thus helping to increase the amount of tinning. Low-temperature surface finishing treatment helps to improve surface adhesion, thereby increasing the amount of tinning, ensuring that the tinning rate of copper and aluminum foil meets market requirements, with no tin falling off and avoiding the use of chemical flux. It effectively solves the problems of low tinning rate, tin falling off, and the need for chemical flux in traditional electrolytic copper foil. It provides a superior alloy material for conductive, heat-dissipating, and lightweight foil fields, and can be widely used in products such as working electronic conductive materials, heat sinks, photovoltaic power generation, electron beam tubes, and LED lighting strips. Detailed Implementation

[0041] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0042] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0043] A method for producing copper and aluminum foil that avoids flux and improves tinning yield includes the following steps:

[0044] 1) Copper and aluminum foil rolling:

[0045] First, the copper-aluminum composite strip T2-8011 must be selected, which must meet the following requirements: the front material of the copper-aluminum composite strip is T2 copper, the back material is 8011 alloy aluminum, and the percentage of copper and aluminum is 20% and 80%, respectively.

[0046] Subsequently, the copper-aluminum composite strip T2-8011 is first polished and then foil rolled to 0.035-0.060mm, with a strip width of 800-1020mm, a thickness tolerance of ±1μm, a copper surface roughness Ra of 0.3-0.6μm, an aluminum surface roughness Ra≤0.5μm, and a surface dyne value of less than 42#.

[0047] 2) Alkali washing:

[0048] Place the copper-aluminum composite strip obtained in step 1) into an immersion tank and perform alkaline washing with organic alkali. The concentration of organic alkali is controlled at 10-15%, the heating temperature is controlled at 50-70℃, and the alkaline washing speed is controlled at 5-15m / min. After alkaline washing, the surface dyne value is less than 36#. After cleaning, wash with deionized water 2-5 times.

[0049] 3) Pickling:

[0050] Place the copper-aluminum composite strip obtained in step 2) into another immersion tank and use dilute sulfuric acid and sodium persulfate for immersion cleaning. The speed is controlled at 5-20 m / min, the concentration of dilute sulfuric acid and sodium persulfate is controlled at 2-5%, and the mass ratio is 1:1. After cleaning, rinse with deionized water 2-5 times.

[0051] The copper-aluminum composite strip is then placed in another immersion tank and cleaned by immersion with dilute sulfuric acid. The concentration of dilute sulfuric acid is controlled at 2-5%, and the pickling speed is controlled at 5-15 m / min. This effectively treats the oxidation and residual oil spots on the surface of the strip. After cleaning, it is rinsed with deionized water 2-5 times, dried, and ready for use.

[0052] 4) Applying adhesive:

[0053] The special adhesive is evenly coated onto the surface of the copper-aluminum composite strip obtained in step 3) using screen printing and pre-treated at a temperature of 135-165℃.

[0054] 5) Tinning:

[0055] On the surface of the copper-aluminum composite strip obtained in step 4), a tin layer is formed by vacuum sputtering. The following conditions must be met: sputtering voltage controlled at 400-450V, sputtering current controlled at 0.2-0.4A, and vacuum degree controlled at (3.3-3.8)×10⁻⁶. - 3 Pa, the tin deposition rate is controlled at 145-155 nm / min;

[0056] Alternatively, the copper-aluminum composite strip obtained in step 4) can be fed into a soldering furnace for tinning. The tinning process is an immersion method, with a furnace length of 1.5m. Resistance wire heating is used, with the temperature controlled at 260-265℃, a tinning speed of 5-15m / min, and strip tension controlled at 0.2kg / mm. 2 Tinning time: 6-18 seconds;

[0057] 6) Low-temperature surface finishing:

[0058] The product obtained in step 5) is passed through a finishing roller to smooth the surface tin. The speed is controlled at 5-15 m / min, the surface roughness Ra of the finishing roller is ≤0.2 μm, the finishing force is 2-3 kg / mm, and the roller surface temperature is controlled at 130-185℃. At this temperature, the surface tin is in a semi-molten state, which makes the tin on the strip surface uniform, delicate and smooth, enhances the surface adhesion, and prevents the surface tin from falling off. The roller surface temperature is controlled by the resistance radiation heating of the roller core.

[0059] After the above steps, the thickness of the obtained tin layer can reach 30-100μm and the distribution is uniform. The tin application rate can reach 75-93%, and no flux is needed, which greatly reduces the production cost.

[0060] In step 4), the raw materials for preparing the special adhesive include the following components in parts by weight:

[0061] 10-20 parts of polyimide-modified phenolic resin

[0062] 5-10 parts of boron nitride

[0063] 4-10 parts of silane coupling agent

[0064] 2-6 parts of cerium dioxide

[0065] 3-8 parts of curing agent.

[0066] Boron nitride is prepared by mixing spherical boron nitride and irregular boron nitride in a weight ratio of 1-2:1-3. The spherical boron nitride is prepared by mixing spherical boron nitride with a particle size of 3.5-5μm and spherical boron nitride with a particle size of 0.3-1.5μm in a weight ratio of 1:2. The irregular boron nitride is prepared by mixing irregular boron nitride with a particle size of 2-6μm and irregular boron nitride with a particle size of 0.1-1.0μm in a weight ratio of 1:2.

[0067] The special adhesive is prepared using the following steps:

[0068] 1) Preparation of polyimide-modified phenolic resin:

[0069] At 95-98℃, polyimide and phenolic resin are stirred and mixed at a weight ratio of 1:1.5. Then, imidazole or polyamide curing agent is added, and the mixture is stirred and mixed to obtain the desired polyimide-modified phenolic resin.

[0070] 2) Mix 10-20 parts of polyimide-modified phenolic resin, 5-10 parts of boron nitride, and half of the silane coupling agent. Stir at 90-95℃ for 20-50 minutes, and control the vacuum at 0.08-0.11 MPa. Then, add 2-6 parts of cerium dioxide and continue stirring. Add the other half of the silane coupling agent and continue stirring. Finally, add 3-8 parts of curing agent and stir until well mixed to obtain the desired special adhesive, which has good bonding properties and is beneficial for increasing the amount of tin applied.

[0071] Example 1

[0072] A method for producing copper and aluminum foil that avoids flux and improves tinning yield includes the following steps:

[0073] 1) Copper and aluminum foil rolling:

[0074] First, the copper-aluminum composite strip T2-8011 must be selected, which must meet the following requirements: the front material of the copper-aluminum composite strip is T2 copper, the back material is 8011 alloy aluminum, and the percentage of copper and aluminum is 20% and 80%, respectively.

[0075] Subsequently, the copper-aluminum composite strip T2-8011 was first polished and then foil rolled to 0.035mm, with a strip width of 800mm, a thickness tolerance of ±1μm, a copper surface roughness Ra of 0.3μm, an aluminum surface roughness Ra≤0.5μm, and a surface dyne value of less than 42#.

[0076] 2) Alkali washing:

[0077] The copper-aluminum composite strip obtained in step 1) was placed in an immersion tank and alkaline washed with sodium methoxide organic alkali. The concentration of organic alkali was controlled at 10%, the heating temperature was controlled at 50℃, and the alkaline washing speed was controlled at 8m / min. After alkaline washing, the surface dyne value was less than 36#. After cleaning, it was washed with deionized water 3 times.

[0078] 3) Pickling:

[0079] The copper-aluminum composite strip obtained in step 2) was placed in another immersion tank and cleaned by immersion with dilute sulfuric acid and sodium persulfate. The speed was controlled at 8 m / min, the concentration of dilute sulfuric acid and sodium persulfate was controlled at 5%, and the mass ratio was 1:1. After cleaning, it was cleaned with deionized water 3 times.

[0080] The copper-aluminum composite strip is then placed in another immersion tank and cleaned by immersion with dilute sulfuric acid. The concentration of dilute sulfuric acid is controlled at 5%, and the pickling speed is controlled at 8m / min. This effectively treats the oxidation and residual oil spots on the surface of the strip. After cleaning, it is rinsed three times with deionized water, dried, and ready for use.

[0081] 4) Applying adhesive:

[0082] The special adhesive is evenly coated onto the surface of the copper-aluminum composite strip obtained in step 3) using screen printing and pre-treated at a temperature of 155℃.

[0083] 5) Tinning:

[0084] The copper-aluminum composite strip obtained in step 4) is fed into a soldering furnace for tinning. The tinning is done using an immersion furnace with a length of 1.5m. Resistance wire heating is used, the temperature is controlled at 260℃, the tinning speed is 5m / min, and the strip tension is controlled at 0.2kg / mm. 2 Tinning time: 10 seconds;

[0085] 6) Low-temperature surface finishing:

[0086] The product obtained in step 5) is passed through a finishing roller to smooth the surface tin. The speed is controlled at 8m / min, the surface roughness Ra of the finishing roller is ≤0.2μm, the finishing force is 2kg / mm, and the roller surface temperature is controlled at 145℃. At this temperature, the surface tin is in a semi-molten state, which makes the tin on the strip surface uniform, delicate and smooth, enhances the surface adhesion, and prevents the surface tin from falling off. The roller surface temperature is controlled by the roller core resistance radiation heating.

[0087] After the above steps, the tinning rate can reach 89%, eliminating the need for flux and greatly reducing production costs.

[0088] In step 4), the raw materials for preparing the special adhesive include the following components in parts by weight:

[0089] 10 parts of polyimide-modified phenolic resin

[0090] 10 parts of boron nitride

[0091] 10 parts of silane coupling agent

[0092] 6 parts of cerium dioxide

[0093] 8 parts of polyamide curing agent.

[0094] Boron nitride is prepared by mixing spherical boron nitride and irregular boron nitride in a weight ratio of 1:2. The spherical boron nitride is prepared by mixing spherical boron nitride with a particle size of 3.5-5 μm and spherical boron nitride with a particle size of 0.3-1.5 μm in a weight ratio of 1:2. The irregular boron nitride is prepared by mixing irregular boron nitride with a particle size of 2-6 μm and irregular boron nitride with a particle size of 0.1-1.0 μm in a weight ratio of 1:2.

[0095] The special adhesive is prepared using the following steps:

[0096] 1) Preparation of polyimide-modified phenolic resin:

[0097] At 98°C, polyimide and phenolic resin are stirred and mixed at a weight ratio of 1:1.5. Then, imidazole or polyamide curing agent is added, and the mixture is stirred and mixed to obtain the desired polyimide-modified phenolic resin.

[0098] 2) Mix 10 parts of polyimide-modified phenolic resin, 10 parts of boron nitride, and half of the silane coupling agent at a stirring temperature of 95°C for 30 minutes, with the vacuum degree controlled at 0.08 MPa. Then, add 6 parts of cerium dioxide and continue stirring. Add the other half of the silane coupling agent and continue stirring. Finally, add 8 parts of curing agent and stir until well mixed to obtain the desired special adhesive, which has good bonding properties and is beneficial for increasing the amount of tin applied.

[0099] Example 2

[0100] A method for producing copper and aluminum foil that avoids flux and improves tinning yield includes the following steps:

[0101] 1) Copper and aluminum foil rolling:

[0102] First, the copper-aluminum composite strip T2-8011 must be selected, which must meet the following requirements: the front material of the copper-aluminum composite strip is T2 copper, the back material is 8011 alloy aluminum, and the percentage of copper and aluminum is 20% and 80%, respectively.

[0103] Subsequently, the copper-aluminum composite strip T2-8011 was first polished and then foil rolled to 0.060mm, with a strip width of 1020mm, a thickness tolerance of ±1μm, a copper surface roughness Ra of 0.6μm, an aluminum surface roughness Ra≤0.5μm, and a surface dyne value of less than 42#.

[0104] 2) Alkali washing:

[0105] The copper-aluminum composite strip obtained in step 1) is placed in an immersion tank and alkaline washing is performed using sodium methoxide organic alkali. The concentration of organic alkali is controlled at 15%, the heating temperature is controlled at 70℃, and the alkaline washing speed is controlled at 15m / min. After alkaline washing, the surface dyne value is less than 36#. After cleaning, it is rinsed 3 times with deionized water.

[0106] 3) Pickling:

[0107] The copper-aluminum composite strip obtained in step 2) was placed in another immersion tank and cleaned by immersion with dilute sulfuric acid and sodium persulfate. The speed was controlled at 5 m / min, the concentration of dilute sulfuric acid and sodium persulfate was controlled at 2%, and the mass ratio was 1:1. After cleaning, it was cleaned with deionized water 3 times.

[0108] The copper-aluminum composite strip is then placed in another immersion tank and cleaned by immersion with dilute sulfuric acid. The concentration of dilute sulfuric acid is controlled at 2%, and the pickling speed is controlled at 5m / min. This effectively removes oxidation and residual oil stains on the surface of the strip. After cleaning, the strip is rinsed three times with deionized water, dried, and set aside for later use.

[0109] 4) Applying adhesive:

[0110] The special adhesive is evenly coated onto the surface of the copper-aluminum composite strip obtained in step 3) using screen printing and pre-treated at a temperature of 135℃.

[0111] 5) Tinning:

[0112] On the surface of the copper-aluminum composite strip obtained in step 4), a tin layer is formed by vacuum sputtering. At this point, the following conditions must be met: sputtering voltage controlled at 450V, sputtering current controlled at 0.4A, and vacuum degree controlled at 3.8×10⁻⁶. -3 Pa, the tin deposition rate was controlled at 155 nm / min;

[0113] 6) Low-temperature surface finishing:

[0114] The product obtained in step 5) is passed through a finishing roller to smooth the surface tin. The speed is controlled at 5m / min, the surface roughness Ra of the finishing roller is ≤0.2μm, the finishing force is 3kg / mm, and the roller surface temperature is controlled at 130℃. At this temperature, the surface tin is in a semi-soft melting state, which makes the tin on the strip surface uniform, delicate and smooth, enhances the surface adhesion, and prevents the surface tin from falling off. The roller surface temperature is controlled by the resistance radiation heating of the roller core.

[0115] In step 4), the raw materials for preparing the special adhesive include the following components in parts by weight:

[0116] 20 parts of polyimide-modified phenolic resin

[0117] 5 parts of boron nitride

[0118] 4 parts of silane coupling agent

[0119] 2 parts of cerium dioxide

[0120] Three parts of polyamide curing agent.

[0121] Boron nitride is prepared by mixing spherical boron nitride and irregular boron nitride in a weight ratio of 2:3. The spherical boron nitride is prepared by mixing spherical boron nitride with a particle size of 3.5-5 μm and spherical boron nitride with a particle size of 0.3-1.5 μm in a weight ratio of 1:2. The irregular boron nitride is prepared by mixing irregular boron nitride with a particle size of 2-6 μm and irregular boron nitride with a particle size of 0.1-1.0 μm in a weight ratio of 1:2.

[0122] The special adhesive is prepared using the following steps:

[0123] 1) Preparation of polyimide-modified phenolic resin:

[0124] At 95°C, polyimide and phenolic resin are stirred and mixed at a weight ratio of 1:1.5. Then, imidazole or polyamide curing agent is added, and the mixture is stirred and mixed to obtain the desired polyimide-modified phenolic resin.

[0125] 2) Mix 20 parts of polyimide-modified phenolic resin, 5 parts of boron nitride, and half of the silane coupling agent at a stirring temperature of 95°C for 20 minutes, with the vacuum degree controlled at 0.11 MPa. Then, add 2 parts of cerium dioxide and continue stirring. Add the other half of the silane coupling agent and continue stirring. Finally, add 3 parts of curing agent and stir until well mixed to obtain the desired special adhesive, which has good bonding properties and is beneficial for increasing the amount of tin applied.

[0126] Same as Example 1.

[0127] Example 3

[0128] A method for producing copper and aluminum foil that avoids flux and improves tinning yield includes the following steps:

[0129] 1) Copper and aluminum foil rolling:

[0130] First, the copper-aluminum composite strip T2-8011 must be selected, which must meet the following requirements: the front material of the copper-aluminum composite strip is T2 copper, the back material is 8011 alloy aluminum, and the percentage of copper and aluminum is 20% and 80%, respectively.

[0131] Subsequently, the copper-aluminum composite strip T2-8011 is first polished and then foil rolled to 0.050mm. The strip width is 800-1020mm, the thickness tolerance is ±1μm, the copper surface roughness Ra is 0.5μm, the aluminum surface roughness Ra≤0.5μm, and the surface dyne value is less than 42#.

[0132] 2) Alkali washing:

[0133] The copper-aluminum composite strip obtained in step 1) is placed in an immersion tank and alkaline washing is performed using organic alkali. The concentration of organic alkali is controlled at 12%, the heating temperature is controlled at 60℃, and the alkaline washing speed is controlled at 12m / min. After alkaline washing, the surface dyne value is less than 36#. After cleaning, it is rinsed with deionized water 3 times.

[0134] 3) Pickling:

[0135] The copper-aluminum composite strip obtained in step 2) was placed in another immersion tank and cleaned by immersion with dilute sulfuric acid and sodium persulfate. The speed was controlled at 12 m / min, the concentration of dilute sulfuric acid and sodium persulfate was controlled at 3%, and the mass ratio was 1:1. After cleaning, it was cleaned with deionized water 3 times.

[0136] The copper-aluminum composite strip is then placed in another immersion tank and cleaned by immersion with dilute sulfuric acid. The concentration of dilute sulfuric acid is controlled at 3%, and the pickling speed is controlled at 12m / min. This effectively removes oxidation and residual oil stains on the surface of the strip. After cleaning, the strip is rinsed three times with deionized water, dried, and set aside for later use.

[0137] 4) Applying adhesive:

[0138] The special adhesive is evenly coated onto the surface of the copper-aluminum composite strip obtained in step 3) using screen printing and pre-treated at a temperature of 165℃.

[0139] 5) Tinning:

[0140] On the surface of the copper-aluminum composite strip obtained in step 4), a tin layer is formed by vacuum sputtering. At this point, the following conditions must be met: sputtering voltage controlled at 400V, sputtering current controlled at 0.2A, and vacuum degree controlled at 3.5×10⁻⁶. -3 Pa, the tin deposition rate was controlled at 145 nm / min;

[0141] 6) Low-temperature surface finishing:

[0142] The product obtained in step 5) is passed through a finishing roller to smooth the surface tin. The speed is controlled at 12m / min, the surface roughness Ra of the finishing roller is ≤0.2μm, the finishing force is 2kg / mm, and the roller surface temperature is controlled at 165℃. At this temperature, the surface tin is in a semi-soft melting state, which makes the tin on the strip surface uniform, delicate and smooth, enhances the surface adhesion, and prevents the surface tin from falling off. The roller surface temperature is controlled by the resistance radiation heating of the roller core.

[0143] In step 4), the raw materials for preparing the special adhesive include the following components in parts by weight:

[0144] 15 parts of polyimide-modified phenolic resin

[0145] 6 parts of boron nitride

[0146] 7 parts of silane coupling agent

[0147] 3 parts of cerium dioxide

[0148] Five parts of curing agent.

[0149] Boron nitride is prepared by mixing spherical boron nitride and irregular boron nitride in a weight ratio of 1:3. The spherical boron nitride is prepared by mixing spherical boron nitride with a particle size of 3.5-5 μm and spherical boron nitride with a particle size of 0.3-1.5 μm in a weight ratio of 1:2. The irregular boron nitride is prepared by mixing irregular boron nitride with a particle size of 2-6 μm and irregular boron nitride with a particle size of 0.1-1.0 μm in a weight ratio of 1:2.

[0150] The special adhesive is prepared using the following steps:

[0151] 1) Preparation of polyimide-modified phenolic resin:

[0152] At 96°C, polyimide and phenolic resin are stirred and mixed at a weight ratio of 1:1.5. Then, imidazole or polyamide curing agent is added, and the mixture is stirred and mixed to obtain the desired polyimide-modified phenolic resin.

[0153] 2) Mix 15 parts of polyimide-modified phenolic resin, 6 parts of boron nitride, and half of the silane coupling agent at a stirring temperature of 90-95℃ for 20-50 minutes, with the vacuum degree controlled at 0.08-0.11MPa. Then, add 3 parts of cerium dioxide and continue stirring. Add the other half of the silane coupling agent and continue stirring. Finally, add 5 parts of curing agent and stir until well mixed to obtain the desired special adhesive, which has good bonding properties and is beneficial for increasing the amount of tin applied.

[0154] Same as Example 2.

[0155] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0156] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for producing a copper-aluminum foil with fluxing aid and improved tinning rate, characterized by, The method comprises the following steps: 1) copper-aluminum foil rolling: selecting a copper-aluminum composite strip, polishing and foil rolling the copper-aluminum composite strip; 2) alkali washing; 3) acid washing; 4) gluing; 5) tin plating; 6) surface low-temperature finishing; In step 1), the copper-aluminum composite strip is T2-8011, the front surface material is T2 red copper, the back surface material is 8011 alloy aluminum, and the percentage of copper and aluminum is 20% and 80%, respectively; The copper-aluminum composite strip is rolled to 0.035-0.060 mm, the strip width is 800-1020 mm, the thickness tolerance is ±1 μm, the copper surface roughness Ra is 0.3-0.6 μm, the aluminum surface roughness Ra is ≤0.5 μm, and the surface D-value is less than 42#; In step 4), the gluing step comprises: uniformly applying a special adhesive to the surface of the copper-aluminum composite strip obtained in step 3) by screen printing and pre-treating, and the temperature is controlled at 135-165℃; The preparation raw materials of the special adhesive comprise the following components in the following weight fractions: polyimide modified phenolic resin 10-20 parts boron nitride 5-10 parts silane coupling agent 4-10 parts cerium dioxide 2-6 parts curing agent 3-8 parts; The boron nitride is prepared by mixing spherical boron nitride and irregular boron nitride in a weight ratio of 1-2:1-3, the spherical boron nitride is prepared by mixing spherical boron nitride with a particle size of 3.5-5 μm and spherical boron nitride with a particle size of 0.3-1.5 μm in a weight ratio of 1:2, and the irregular boron nitride is prepared by mixing irregular boron nitride with a particle size of 2-6 μm and irregular boron nitride with a particle size of 0.1-1.0 μm in a weight ratio of 1:

2.

2. The copper-aluminum foil production method of claim 1, wherein, In step 2), the alkali washing step comprises: placing the copper-aluminum composite strip obtained in step 1) in a soaking box, using an organic alkali for alkali washing, controlling the concentration of the organic alkali at 10-15%, controlling the heating temperature at 50-70℃, controlling the alkali washing speed at 5-15 m / min, and controlling the surface D-value after alkali washing to be less than 36#, and using deionized water for cleaning 2-5 times after cleaning.

3. The copper-aluminum foil production method of claim 1, wherein the fluxing agent is applied to the surface of the copper foil in a thickness of 0.1 to 1.0 μm. In step 3), the acid washing step comprises: placing the copper-aluminum composite strip obtained in step 2) in a soaking box, using dilute sulfuric acid and sodium persulfate for soaking cleaning, controlling the speed at 5-20 m / min, controlling the concentration of dilute sulfuric acid and sodium persulfate at 2-5%, and controlling the mass ratio at 1:1, and using deionized water for cleaning 2-5 times after cleaning; then, placing the copper-aluminum composite strip in another soaking box, using dilute sulfuric acid for soaking cleaning, controlling the concentration of dilute sulfuric acid at 2-5%, controlling the acid washing speed at 5-15 m / min, and using deionized water for cleaning 2-5 times after cleaning, and drying for standby.

4. The copper-aluminum foil production method of claim 1, wherein the fluxing agent is applied to the surface of the copper foil in a thickness of 0.1 to 1.0 μm. The special adhesive is prepared by the following steps: 1) preparing polyimide modified phenolic resin: stirring and uniformly mixing polyimide and phenolic resin at a weight ratio of 1:1.5 at 95-98℃, then adding imidazole or polyamide curing agent, and stirring and uniformly mixing to obtain the required polyimide modified phenolic resin; 2) mixing polyimide modified phenolic resin 10-20 parts, boron nitride 5-10 parts and half amount of silane coupling agent by stirring, stirring temperature is 90-95℃, stirring time is 20-50min, vacuum degree is controlled in 0.08-0.11MPa, then, adding cerium dioxide 2-6 parts, continuing to stir and mix, adding another half amount of silane coupling agent, continuing to stir and mix, adding curing agent 3-8 parts, stirring and mixing, obtaining the required special adhesive.

5. The copper-aluminum foil production method of claim 1, wherein the fluxing agent is applied to the surface of the copper foil in a thickness of 0.1 to 1.0 μm. The step of tin plating in step 5) comprises: In step 4), a tin layer is formed on the surface of the copper-aluminum composite strip obtained in step 3) by vacuum sputtering, and the sputtering voltage is controlled at 400-450 V, the sputtering current is controlled at 0.2-0.4 A, the vacuum degree is controlled at (3.3-3.8) x 10 -3 Pa, and the tin deposition rate is controlled at 145-155 nm / min. In step 5), the tin layer is annealed at 200-250°C for 1-2 hours.

6. The copper-aluminum foil production method of claim 1, wherein the fluxing agent is applied to the surface of the copper foil in a thickness of 0.1 to 1.0 μm. The step of tin plating in step 5) comprises: The copper-aluminum composite strip obtained in step 4) is sent into a tin melting furnace for tin hanging, the tin melting is of immersion type, the furnace body length is 1.5 m, the heating is by resistance wire, the temperature is controlled at 260-265℃, the tin hanging speed is 5-15 m / min, the strip tension is controlled at 0.2 kg / mm 2 , and the tin hanging time is 6-18 s.

7. The copper-aluminum foil production method of claim 1, wherein the fluxing agent is applied to the surface of the copper foil in a thickness of 0.1 to 1.0 μm. The step of surface low-temperature finishing in step 6) comprises: The product obtained in step 5) is passed through a finishing roller to level the surface tin, the speed is controlled in 5-15m / min, the surface roughness Ra of the finishing roller is ≤0.2μm, the finishing force is 2-3kg / mm, and the roller surface temperature is controlled in 130-185℃, at which the surface tin is in semi-soft melting state, so that the surface tin of the strip is uniform, delicate and smooth, the surface adhesion is enhanced, and the surface tin is prevented from falling off; the thickness of the tin layer reaches 30-100μm, is uniformly distributed, and the tin plating rate reaches 75-93%.