Lead frame raw material surface treatment method

Abstract

The invention provides a lead frame raw material surface treatment method. The method comprises the following steps: providing a pretreated lead frame raw material; placing the pretreated lead frame raw material in a copper pre-plating solution, applying an ultrasonic field in the copper pre-plating solution, and pre-plating a copper layer on the surface of the lead frame raw material under the action of the ultrasonic field; and performing infrared heating on the discharge end of the lead frame raw material pre-plated with the copper layer to obtain the lead frame raw material with the required surface state. According to the method, a uniform and compact pre-plated copper layer can be formed, the subsequent electroplating effect is improved, and large-scale preparation of the high-performance lead frame is realized.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor lead frames, and in particular to a surface treatment method for lead frame raw materials. Background Art

[0002] The semiconductor lead frame is a key structural component that connects the internal circuit of the integrated circuit chip with the external circuit and forms an electrical circuit. The uniformity, bonding strength and flatness of its surface coating directly determine the chip packaging reliability and electrical performance.

[0003] In the existing process, the lead frame usually needs to be pre-treated before electroplating, including degreasing, pickling, water washing and drying. The surface of the rolled copper foil used as the raw material of the lead frame in this process has not been specially treated, and the surface of the rolled copper foil has its own rolling lines and is easily oxidized, resulting in poor surface adhesion of the rolled copper foil substrate to the pressing film, which in turn affects the surface uniformity and flatness of the subsequent electroplated silver coating. On the other hand, the existing pre-treatment process has the problem of insufficient water washing efficiency after pickling, and residual chemicals (such as acid solution, etc.) are easy to contaminate the subsequent electroplating solution, causing abnormal local deposition of the coating, aggravating surface unevenness, and seriously affecting the packageability of the lead frame.

[0004] Some researchers have attempted to improve the shortcomings of these technologies. Patent CN101314832A improves the packageability of lead frames by pre-plating copper on the substrate surface, then plating nickel and copper to form a copper-nickel-copper three-layer coating. However, this method does not fully consider the uniformity control of the pre-plating layer. The electroplating effect of different metals is affected by multiple factors such as the current, temperature, electroplating solution concentration, and additive type during the electroplating process. Therefore, each electroplated layer may have some deposition pore defects and easily delaminate and fall off. Patent CN118621396A adopts a method of first plating nickel, then copper, and finally silver, and slowly heating and annealing the frame material after each electroplating to improve the uniformity of the coating. However, this method requires activation and water washing before each layer of material is electroplated, which adds multiple processes, making the quality consistency of batch products difficult to control and time-consuming. In addition, copper alloy lead frames containing materials such as lead or tin will react with nickel, and the nickel element is magnetic, which may affect the magnetic field distribution of the lead frame, thereby affecting the chip electrical signal transmission.

[0005] Therefore, it is urgent to develop a lead frame raw material pre-treatment process to solve at least one of the above technical problems. Summary of the Invention

[0006] In view of the defects in the prior art, the purpose of the present invention is to provide a surface treatment method for lead frame raw materials to form a uniform and dense pre-plated copper layer, improve the subsequent electroplating effect, and realize the large-scale preparation of high-performance lead frames.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The present invention provides a surface treatment method for a lead frame raw material, comprising:

[0009] Provide pre-processed lead frame raw materials;

[0010] Placing the pretreated lead frame raw material in a pre-copper plating solution, applying an ultrasonic field to the pre-copper plating solution, and pre-plating a copper layer on the surface of the lead frame raw material under the action of the ultrasonic field;

[0011] The discharge end of the lead frame raw material with the pre-copper plating layer is subjected to infrared heating to obtain the lead frame raw material with a desired surface state.

[0012] Optionally, the pretreated lead frame raw material is placed in a pre-copper plating solution, wherein the pre-copper plating solution comprises the following components in weight percentage: 10% to 20% copper sulfate, 5% to 10% sulfuric acid, 0.01% to 0.05% chloride ion, 0.1% to 0.5% brightener, 0.05% to 0.1% leveler, and the balance is water.

[0013] Optionally, the brightener is one or more of sodium polydisulfide propane sulfonate, ethylene thiourea and sodium saccharin; and the leveler is one or more of polyacrylamide, polyethylene imine and polyethylene glycol.

[0014] Optionally, an ultrasonic field is applied to the pre-copper plating solution, wherein the frequency of the applied ultrasonic field is 10 kHz to 100 kHz.

[0015] Optionally, the copper layer is pre-plated on the surface of the lead frame raw material under the action of the ultrasonic field, wherein: the temperature is 15°C to 35°C, the time is 1 minute to 10 minutes, and the current density is 0.1A / dm 2 ~4A / dm 2 .

[0016] Optionally, the discharge end of the lead frame raw material with the pre-copper plated layer is subjected to infrared heating, wherein: the heating temperature is 150° C. to 350° C., and the heating time is 3 seconds to 60 seconds.

[0017] Optionally, providing the pretreated lead frame raw material includes: sequentially performing alkaline degreasing, a first water washing, a gradient deoxidation treatment, and a second water washing on the lead frame raw material.

[0018] Optionally, the gradient deoxidation treatment includes: first placing the lead frame raw material in a pickling solution for pickling treatment, and then placing it in an activation solution for activation treatment.

[0019] Optionally, the pickling solution comprises the following components in volume percentage: 10% to 20% sulfuric acid, 5% to 10% hydrogen peroxide, 0.1% to 0.5% corrosion inhibitor, and the balance is water; the activation solution contains 1% to 10% fluoroboric acid.

[0020] Optionally, the temperature of the pickling solution is 25° C. to 55° C., the pickling treatment time is 0.1 minute to 5 minutes, and the activation treatment time is 0.1 minute to 5 minutes.

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

[0022] 1. The present invention combines ultrasound with a pre-copper plating layer to ensure that the pre-copper plating solution on the lead frame raw material surface tends to be uniform at any time during the electroplating process, thereby obtaining a uniform and dense deposition base, reducing lattice mismatch, and enhancing interlayer bonding. This solves the problems of conventional lead frame raw material pre-plating uniformity, the potential for deposition porosity defects in multiple plating layers, and the subsequent delamination and shedding of the plating. Furthermore, by pre-electroplating a transition layer of copper, the surface texture of the lead frame raw material rolled copper foil can be filled, effectively improving the surface uniformity and flatness of the rolled copper raw material, thereby improving the surface bonding between the lead frame and the die, and enhancing the surface effect of subsequent silver electroplating.

[0023] 2. The present invention adopts infrared local heating to quickly heat only a local area of the lead frame in a short time, thereby promoting the dislocation rearrangement of the material at the contact interface between the coating and the raw material, and quickly releasing the internal residual stress, thereby avoiding local warping and deformation during lead frame packaging, thereby effectively improving the packaging performance of the lead frame.

[0024] 3. The process of the present invention is simple, and there is no need to frequently replace the electroplating solution, nor is there any need to add activation, water washing and other steps before each electroplating. It has the advantages of less time consumption, high efficiency and simple method. The method of the present invention is easy to mass-produce high-performance lead frames. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0026] Figure 1 FIG. 4 is a process flow chart of a surface treatment method for a lead frame raw material in one embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0028] Reference Figure 1 As shown, a lead frame raw material surface treatment method provided by an embodiment of the present invention includes the following steps:

[0029] M1. Provide pre-treated lead frame raw materials;

[0030] M2. Copper plating-ultrasonic coupling: The pretreated lead frame raw material is placed in a pre-copper plating solution, and an ultrasonic field is applied to the pre-copper plating solution to pre-plate a copper layer on the surface of the lead frame raw material under the action of the ultrasonic field;

[0031] M3. Infrared heating: Infrared heating is performed on the discharge end of the lead frame raw material with the pre-copper layer to obtain the lead frame raw material with the desired surface state.

[0032] Specifically, the discharge end refers to the part of the material that comes out of the electroplating solution after the electroplating is completed. When discharging, the material goes from below the liquid surface of the pre-copper plating solution to above the liquid surface. Infrared heating is aimed at the sub-liquid part of the material discharge, which can effectively prevent oxidation of the infrared heating area.

[0033] In the embodiments of the present invention, infrared heating can precisely control the heating area, resulting in a relatively concentrated heat distribution. Because only the discharge area of the material is heated, heating time is short and can be performed simultaneously with electroplating without affecting the plating process. Other methods of heat conduction heating, on the other hand, are inefficient, unable to provide targeted localized heating at a specific location, and require a long heating time. Furthermore, simultaneous electroplating is not easily possible. When the entire material is heated during the electroplating process, the temperature of the plating solution also rises, and excessively high temperatures can seriously affect the quality of the electroplating process.

[0034] The method provided by the embodiment of the present invention adopts the method of ultrasonic coupling pre-copper plating layer, so that the pre-copper plating liquid on the surface of the lead frame raw material tends to be uniform at any time during the electroplating process, which can reduce the lattice mismatch of the pre-copper plating layer, enhance the interlayer bonding strength, and provide a uniform and dense deposition base for subsequent silver plating, copper plating, etc., and solves the problems of conventional lead frame raw material pre-plating uniformity being difficult to control, multiple plating layers may have deposition pore defects, and further lead to plating layer delamination and shedding. In addition, by pre-plating a transition layer of copper on the surface of the rolled copper foil of the lead frame raw material, the surface texture of the rolled copper foil is filled, and the surface uniformity and flatness of the rolled copper raw material are effectively improved, thereby improving the surface bonding strength between the lead frame and the die, as well as the surface effect of subsequent electroplating silver.

[0035] In addition, the embodiment of the present invention can also promote the dislocation rearrangement of the material at the contact interface between the coating and the raw material through infrared rapid local heating, quickly release the residual stress inside the lead frame raw material in a short time, and avoid local warping and deformation during lead frame packaging, thereby effectively improving the packageability of the lead frame and improving the production efficiency of electrical contact materials. The method provided by the embodiment of the present invention has the advantages of less time consumption, simple processing method, and easy mass production of high-performance lead frame products, which is conducive to reducing the manufacturing cost of lead frame products.

[0036] To provide a pretreated lead frame raw material, in some embodiments, in step M1 , the lead frame raw material is sequentially subjected to alkaline degreasing, a first water washing, a gradient deoxidation treatment, and a second water washing.

[0037] In order to achieve alkaline degreasing, the lead frame raw material is placed in an alkaline degreasing agent at 40°C to 70°C and degreased for 1 minute to 10 minutes.

[0038] Illustratively, the alkaline degreasing agent includes the following components in weight percentage: 5% to 10% sodium hydroxide, 3% to 5% sodium carbonate, 1% to 2% sodium silicate, 2% to 4% sodium tripolyphosphate, 0.5% to 1% surfactant, and the balance is water.

[0039] In some preferred embodiments, the surfactant is one or more of sodium dodecylbenzene sulfonate, fatty alcohol polyoxyethylene ether and sodium lauryl sulfate, so as to reduce surface tension, emulsify and disperse oil stains, and enhance cleaning effects.

[0040] Through the alkaline degreasing treatment, no grease residues are left on the surface of the lead frame raw material.

[0041] To prevent the effects of residual alkaline degreaser on subsequent processes, a first water wash is performed after alkaline degreasing. Specifically, the degreased lead frame material is rinsed with deionized water. This water wash neutralizes the alkaline surface environment, effectively removing residual alkaline degreaser and ensuring surface cleanliness.

[0042] To further remove surface oxides and other impurities, the lead frame raw material undergoes a gradient deoxidation treatment. In some embodiments, this gradient deoxidation treatment includes: first, immersing the lead frame raw material in an acid wash solution such as sulfuric acid to remove surface oxides such as aluminum oxide; then, activating the lead frame raw material surface in an activation solution to improve the bonding strength of the copper plating layer in the subsequent pre-copper plating step.

[0043] In some embodiments, the pickling solution includes the following components in volume percentages: 10% to 20% sulfuric acid, 5% to 10% hydrogen peroxide, 0.1% to 0.5% corrosion inhibitor, and the balance is water; the activation solution includes 1% to 10% fluoroboric acid.

[0044] The corrosion inhibitor must effectively inhibit the corrosion of the copper substrate (>90%) in a strong acid environment (such as sulfuric acid and hydrochloric acid), but allow the oxide layer (such as CuO, Al2O3, etc.) to be fully dissolved. The following factors should be considered when setting the corrosion inhibitor: (1) Chemical stability: Stable existence in acidic media; (2) Thermal stability: No thermal decomposition occurs during high-temperature pickling; (3) Whether it will affect the surface morphology or roughness of the lead frame raw material.

[0045] In some preferred embodiments, the corrosion inhibitor is one or more of benzotriazole, toluenetriazole and thiourea, so as to protect the lead frame raw material from being excessively corroded during the pickling process.

[0046] The formula of the above pickling solution takes into account factors such as the efficiency of removing surface oxides and the protection of the substrate. It can not only completely remove the oxides on the surface of the lead frame raw material, but also will not excessively corrode the raw material base material itself.

[0047] The process parameters for the gradient deoxidation treatment in the embodiments of the present invention are determined based on factors such as the composition of the pickling solution and activation solution, the efficiency of removing surface oxides, and the surface roughness required for pre-copper plating. In some embodiments, the pickling solution temperature is 25°C to 55°C, the pickling treatment time is 0.1 to 5 minutes, and the activation treatment time is 0.1 to 5 minutes, thereby preventing defects such as pitting, pitting, and partial coating shedding in the subsequent pre-copper plating process.

[0048] By the gradient deoxidation treatment, surface oxide impurities are removed in stages and step by step, and the oxide passivation layers such as CuO and Al2O3 on the surface of the lead frame raw material can be completely removed, further improving the surface bonding strength between the lead frame raw material and the coating.

[0049] It should be noted that conventional pretreatment processes mainly involve alkaline degreasing and water washing, followed by pickling and water washing. The above embodiment of the present invention divides the pickling into two stages through gradient deoxidation. The first stage is mainly for removing oxides, and the second stage is mainly for activating the material surface to prepare for improving the bonding strength of the subsequent pre-copper plating process.

[0050] To prevent subsequent processes from being affected by residual pickling solution or activation solution, a second water wash is performed after the gradient deoxidation treatment. Specifically, the lead frame raw material is rinsed with deionized water to remove residual pickling solution and other surface residues. This water wash neutralizes the surface acidity and ensures the surface cleanliness of the lead frame raw material.

[0051] To achieve a uniform and dense pre-plated layer on the lead frame raw material, the formula of the pre-copper plating solution is determined by considering factors such as the pre-plated metal deposition effect, pre-plated layer adhesion, pre-plated layer thickness, and pre-plated layer surface condition. In some embodiments, in step M2, the pre-copper plating solution includes the following components in weight percentage: 10% to 20% copper sulfate, 5% to 10% sulfuric acid, 0.01% to 0.05% chloride ion, 0.1% to 0.5% brightener, 0.05% to 0.1% leveler, and the balance is water.

[0052] In some embodiments, the brightener is one or more of sodium polydisulfide propane sulfonate, ethylene thiourea, and sodium saccharin, which forms an adsorption layer to optimize metal deposition, eliminate the frosted surface of the pre-plated copper layer, and make the plated layer smoother and brighter. The leveler is one or more of polyacrylamide, polyethyleneimine, and polyethylene glycol, which can adjust the grain structure of the electroplated copper, making the plated layer more uniform and level, while also enhancing the adhesion of the electroplated copper and preventing hydrogen embrittlement during the pre-plating process.

[0053] In some embodiments, the frequency of the applied ultrasonic field is between 10 kHz and 100 kHz.

[0054] In some embodiments, a copper layer is pre-plated on the surface of the lead frame raw material under the action of an ultrasonic field, wherein: the temperature is 15°C to 35°C, the time is 1 minute to 10 minutes, and the current density is 0.1A / dm 2 ~4A / dm 2 .

[0055] The electroplating and ultrasonic field application process parameters are determined based on factors such as pre-plating efficiency, pre-plating layer thickness, pre-plating layer flatness, pre-plating layer porosity, and the size of the surface texture of the rolled copper foil. These parameters are designed to fully fill the surface texture of the rolled copper foil of the lead frame raw material, resulting in a uniform and dense pre-plated copper layer on the surface of the rolled copper foil. By setting these process parameters, the pre-plating copper solution on the lead frame raw material surface tends to be uniform at any time during the electroplating process, thereby obtaining a uniform and dense deposition base, reducing lattice mismatch, and improving defects such as porosity and delamination in the pre-plated copper layer.

[0056] In the above embodiment of the present invention, an ultrasonic field is coupled during the pre-copper plating process. By combining the above ultrasonic field with electroplating, the porosity of the pre-copper plating layer can be reduced, and a uniform and dense pre-copper plating layer can be formed on the surface of the lead frame raw material, providing a good foundation for subsequent silver electroplating and copper electroplating.

[0057] In some embodiments, in step M3, an infrared heating device is used to heat the discharge end of the lead frame raw material in a pre-copper plating solution at a temperature of 150° C. to 350° C. for a time of 3 seconds to 60 seconds, thereby promoting dislocation rearrangement at the contact interface, releasing residual stress inside the lead frame, avoiding local warping and deformation during lead frame packaging, and improving the surface bonding strength of the lead frame product.

[0058] To improve the surface cleanliness of the lead frame raw material, in a further embodiment, after step M3, a third water wash is further performed. Specifically, the lead frame raw material after pre-copper plating is washed with deionized water to remove the pre-copper plating solution remaining on the surface.

[0059] In a further embodiment, after the third water washing, the lead frame raw material is further dried. Specifically, the drying temperature is 70° C. to 120° C., and the drying time is 1 minute to 10 minutes to remove moisture from the surface of the lead frame raw material and prevent discoloration.

[0060] Below in conjunction with specific embodiment and comparative example, the scheme of the application will be explained.It will be appreciated by those skilled in the art that the following examples are merely used to illustrate the application and should not be considered as limiting the scope of the application.Unindicated specific techniques or conditions in the examples, according to the technology or conditions described in the literature in this area or according to the product specifications.Reagents used or instruments that do not indicate manufacturers are conventional products that can be obtained through commercial routes.

[0061] Example 1

[0062] This embodiment provides a pre-treatment process for T2 rolled copper foil, a raw material for a lead frame, comprising the following steps:

[0063] Step S1: Immerse a T2 rolled copper foil lead frame material (0.25 mm thick) in an alkaline degreaser at 55°C for 5 minutes. The alkaline degreaser composition (by weight): 8% sodium hydroxide, 4% sodium carbonate, 3% sodium tripolyphosphate, 1.5% sodium silicate, 0.8% sodium dodecylbenzene sulfonate, and the balance deionized water.

[0064] Step S2: The T2 rolled copper foil is cleaned with deionized water for 30 seconds to ensure that there is no residue on the surface.

[0065] Step S3: The material obtained in S2 is first immersed in a 35°C pickling solution for 0.5 minutes, and then immediately transferred to an activation solution containing 5% fluoroboric acid at 30°C for 1 minute. The pickling solution comprises (volume percentage): 15% sulfuric acid, 8% hydrogen peroxide, 0.3% benzotriazole, and the balance water.

[0066] Step S4: The deoxidized T2 rolled copper foil is rinsed with deionized water for 20 seconds to completely remove the acid residue.

[0067] Step S5: Immerse the T2 rolled copper foil in a pre-copper plating solution at 25° C., and simultaneously apply a 40 kHz, 200 W ultrasonic field to the pre-copper plating solution for 3 minutes at a current density of 2 A / dm². The pre-copper plating solution comprises (by weight percentage): 15% copper sulfate, 8% sulfuric acid, 0.03% chloride ion, 0.3% sodium polydisulfide dipropylene sulfonate (brightener), 0.08% polyacrylamide (leveling agent), and the balance water.

[0068] Step S6: Use an infrared heating device to locally heat the material discharge end at a temperature of 300° C. for 20 seconds, and monitor the temperature uniformity using an infrared thermal imager.

[0069] Step S7: The T2 rolled copper foil after infrared heating is washed with deionized water at room temperature for 40 seconds to remove the residual plating solution on the surface.

[0070] Step S8: drying the T2 rolled copper foil after the S7 treatment with hot air at a temperature of 75° C. for 5 minutes, thereby obtaining a lead frame substrate with a smooth surface and no oxidation.

[0071] Example 2

[0072] This embodiment provides a pre-treatment process for rolled copper foil made of C19400 iron bronze, a raw material for a lead frame, comprising the following steps:

[0073] Step S1: Immerse a lead frame material (0.2mm thick) made of C19400 rolled copper foil in an alkaline degreaser at 40°C for 8 minutes. The alkaline degreaser composition (by weight): 10% sodium hydroxide, 3% sodium carbonate, 2.2% sodium tripolyphosphate, 1.2% sodium silicate, 0.5% fatty alcohol polyoxyethylene ether, and the balance deionized water.

[0074] Step S2: Clean the C19400 rolled copper foil with deionized water for 40 seconds to ensure that there is no residue on the surface.

[0075] Step S3: The material obtained in S2 is first immersed in a 25°C pickling solution for 3 minutes, and then immediately transferred to an activation solution containing 2% fluoroboric acid at 25°C for 4 minutes. The pickling solution comprises (volume percentage): 12% sulfuric acid, 10% hydrogen peroxide, 0.15% methylbenzotriazole, and the balance water.

[0076] Step S4: The deoxidized C19400 rolled copper foil is rinsed with deionized water for 30 seconds to completely remove the acid residue.

[0077] Step S5: Immerse the C19400 rolled copper foil in a pre-copper plating solution at 15° C., and simultaneously apply an 80 kHz, 200 W ultrasonic field to the pre-copper plating solution for 5 minutes at a current density of 0.5 A / dm². The pre-copper plating solution comprises (by weight percentage): 20% copper sulfate, 5% sulfuric acid, 0.04% chloride ion, 0.15% ethylene thiourea (brightener), 0.05% polyethyleneimine (leveler), and the balance water.

[0078] Step S6: Use an infrared heating device to locally heat the material discharge end at a temperature of 200° C. for 55 seconds, and monitor the temperature uniformity using an infrared thermal imager.

[0079] Step S7: The infrared-heated C19400 rolled copper foil is washed with deionized water at room temperature for 30 seconds to remove residual plating solution on the surface.

[0080] Step S8: drying the C19400 rolled copper foil after the treatment in S7 with hot air at a temperature of 80° C. for 3 minutes, thereby obtaining a lead frame substrate with a smooth surface and no oxidation.

[0081] Comparative Example

[0082] In the comparative example, the lead frame raw material of the T2 rolled copper foil was pre-treated using a conventional process, wherein the conventional pre-treatment process includes: alkaline degreasing-water washing-acid washing-water washing-drying.

[0083] The surface oil residue, surface roughness, and surface bonding strength of the finished lead frame raw material of T2 rolled copper foil prepared in the embodiment of the present invention were compared with those of the lead frame raw material of T2 rolled copper foil in the comparative example. The detailed results are shown in Table 1 below.

[0084] Table 1 Performance characterization results of lead frame raw material finished products

[0085]

[0086] It should be noted that after the lead frame is pre-copper-plated, it is usually subjected to silver plating or other treatments. Surface bonding mainly refers to the bonding strength between the lead frame raw material and the die, which indirectly affects the bonding strength between the lead frame and the plastic used in the chip packaging, that is, the packaging performance.

[0087] As can be seen from Table 1, the lead frame raw material pretreatment process provided by the present invention can effectively remove oil stains and oxides on the lead frame surface, reduce surface roughness, fill the rolling grooves of the rolled copper foil, form a uniform and dense pre-plated copper layer, and improve the subsequent electroplating effect.

[0088] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various modifications or variations within the scope of the claims without affecting the essence of the present invention. The above preferred features may be used in any combination as long as they do not conflict with each other.

Claims

1. A surface treatment method for a lead frame raw material, characterized in that: include: Provide pre-processed lead frame raw materials; Placing the pretreated lead frame raw material in a pre-copper plating solution, applying an ultrasonic field to the pre-copper plating solution, and pre-plating a copper layer on the surface of the lead frame raw material under the action of the ultrasonic field; The discharge end of the lead frame raw material with the pre-copper plating layer is subjected to infrared heating to obtain the lead frame raw material with a desired surface state.

2. The lead frame raw material surface treatment method according to claim 1, characterized in that: The pretreated lead frame raw material is placed in a pre-copper plating solution, wherein the pre-copper plating solution comprises the following components in weight percentage: 10% to 20% copper sulfate, 5% to 10% sulfuric acid, 0.01% to 0.05% chloride ion, 0.1% to 0.5% brightener, 0.05% to 0.1% leveler, and the balance is water.

3. The lead frame raw material surface treatment method according to claim 2, characterized in that: The brightener is one or more of sodium polydisulfide propane sulfonate, ethylene thiourea and sodium saccharin; and the leveling agent is one or more of polyacrylamide, polyethylene imine and polyethylene glycol.

4. The lead frame raw material surface treatment method according to claim 1, characterized in that: An ultrasonic field is applied to the pre-copper plating solution, wherein the frequency of the applied ultrasonic field is 10kHz to 100kHz.

5. The lead frame raw material surface treatment method according to claim 1, characterized in that: The copper layer is pre-plated on the surface of the lead frame raw material under the action of the ultrasonic field, wherein: the temperature is 15°C to 35°C, the time is 1 minute to 10 minutes, and the current density is 0.1A / dm 2 ~4A / dm 2 .

6. The lead frame raw material surface treatment method according to claim 1, characterized in that: The discharge end of the lead frame raw material of the pre-copper plating layer is subjected to infrared heating, wherein: the heating temperature is 150° C. to 350° C., and the heating time is 3 seconds to 60 seconds.

7. The lead frame raw material surface treatment method according to claim 1, characterized in that: The method of providing the pretreated lead frame raw material comprises: sequentially performing alkaline degreasing, a first water washing, a gradient deoxidation treatment and a second water washing on the lead frame raw material.

8. The lead frame raw material surface treatment method according to claim 7, characterized in that: The gradient deoxidation treatment comprises: firstly placing the lead frame raw material in a pickling solution for pickling treatment, and then placing it in an activation solution for activation treatment.

9. The lead frame raw material surface treatment method according to claim 8, characterized in that: The pickling solution comprises the following components in volume percentage: 10% to 20% sulfuric acid, 5% to 10% hydrogen peroxide, 0.1% to 0.5% corrosion inhibitor, and the balance is water; the activation solution contains 1% to 10% fluoroboric acid.

10. The lead frame raw material surface treatment method according to claim 8, characterized in that: The temperature of the pickling solution is 25° C. to 55° C., the pickling treatment time is 0.1 minute to 5 minutes, and the activation treatment time is 0.1 minute to 5 minutes.

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