Single-face coarsening process of lead frame
Through a single-sided roughening process, the copper ions are deposited on the surface of the lead frame using electroplating crude copper potion, combined with bidirectional pulse current and additives, the problem of complex and non-selective lead frame roughening process in the prior art is solved, and more efficient Production process and lower costs while increasing coating roughness and packaging bonding.
Patent Information
- Application Number
- CN202411664974.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-20
- Publication Date
- 2025-01-10
AI Technical Summary
The existing lead frame roughening process is complex, which increases production difficulty and cost, and lacks selectivity, resulting in metal loss and wastewater treatment pressure, micro-etching unevenness and poor appearance problems.
A single-sided roughening process is adopted to form a rough plating layer on the surface of the frame by depositing copper ions in electroplating crude copper potion. The roughness of the plating layer is controlled using bidirectional pulse current and additives to reduce the treatment area and wastewater generation.
It shortens the electroplating production process, reduces production costs and metal losses, improves the plating roughness and packaging bonding, reduces the defect rate and wastewater treatment pressure, and is suitable for a variety of materials and packaging types.
Smart Images
Figure CN119287459A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of lead frame roughening, and in particular to a single-side roughening process of a lead frame. Background Art
[0002] Most of the roughening processes in the industry are "subtractive" processes, that is, the surface of the frame is micro-etched into a rough surface by chemical or electrochemical means on the frame substrate or plating. Among them, because copper itself is easily corroded, the current "subtractive" process production process is basically to roughen the copper alloy frame, that is, the roughening copper process, and its production process is "lead frame forming → degreasing → roughening → pickling → electroplating → pickling → protective water" or "lead frame forming → degreasing → pickling → electroplating → roughening → pickling → protective water". The roughening process has become a pre-treatment or post-treatment section of the lead frame electroplating production, which increases the complexity of the lead frame electroplating manufacturing and brings additional production difficulties and costs; at the same time, the micro-etching of the lead frame by the roughening solution also causes the loss of metallic copper, the copper content continues to rise, and high-concentration copper-containing wastewater is continuously produced, which increases the pressure of wastewater treatment. Moreover, in terms of the principle of micro-etching, the roughening solution of chemical micro-etching has simple reaction conditions, and the splashing and overflow of the solution during the production process can easily cause uneven micro-etching and poor appearance on the lead frame, reducing the production yield and increasing the cost of production control and quality inspection. Electrochemical micro-etching will produce a large amount of metal copper mud on the cathode conductive plate. On the one hand, there is a risk of copper debris adhering to the lead frame, and on the other hand, it may cause a short circuit between the lead frame and the cathode conductive plate, requiring frequent cleaning or replacement of the conductive plate, which brings jams and inconvenience to continuous production, consumes more manpower, and increases the difficulty of production control.
[0003] At the same time, the existing roughening technology lacks selectivity. During production, the lead frame is immersed or sprayed as a whole, which will roughen the lead frame as a whole. On the one hand, compared with selective roughening, in addition to bringing higher production costs such as precious metals and wastewater treatment, the excessively large processing area also faces greater risks of defects due to the large surface area of the copper surface, which is very easy to adhere to foreign matter or be contaminated during the production process, increasing the pressure of production control and quality inspection; on the other hand, the lead frame is not encapsulated as a whole, and during the encapsulation production process, the plastic encapsulation glue will overflow to the non-encapsulation area, which will cause subsequent production defects, and even directly cause the mold to collapse and cause permanent damage. In addition to increasing the surface area of the lead frame encapsulation area and enhancing its bonding with the plastic encapsulation glue, the overall roughening also increases the bonding between the non-encapsulation area and the plastic encapsulation overflow glue during the plastic encapsulation production, which increases the difficulty of removing the overflow glue, and becomes a pain point in the application of roughened lead frames.
[0004] Therefore, there is a need for a roughening process that can shorten the lead frame electroplating production process without causing metal loss, reducing wastewater treatment costs, and reducing the treatment area. Summary of the invention
[0005] The purpose of this application is to provide a single-sided roughening process for a lead frame in view of the shortcomings of the current technology. The single-sided roughening process for the lead frame of this application belongs to the "addition" process of roughening, which belongs to the reverse process of the "subtraction" process, and the copper ions in the electroplating crude copper solution are deposited on the surface of the lead frame. In this process, the copper ions of the electroplating crude copper solution will only be continuously consumed, and high-concentration copper-containing wastewater will not be continuously produced. Moreover, even if the production process will continuously replenish the copper content to maintain the copper ion concentration to ensure the roughening effect, the increase in the copper content of the electroplating crude copper solution will also be in a controlled state, and ultimately will not cause high-concentration copper-containing wastewater. The "addition" process is a kind of electroplating roughening technology, which uses a specially formulated copper plating solution for electroplating, and directly electroplates a rough coating on the surface of the frame. The process can strictly control the occurrence and stop of roughening by turning on and off the current, and will not cause uneven roughening and poor appearance due to splashing or overflow of the electroplating crude copper solution to the lead frame of the non-electroplating section.
[0006] The additives in the electroplating copper solution of the present application can adjust the secondary current distribution and inhibit the electrochemical reaction in the high current density area. When using bidirectional pulse current for electroplating, the forward current is close to the limiting current density, copper is rapidly deposited on the surface of the frame, and the crystals grow rapidly to form prismatic dendrites with dendrite characteristics. Due to the inhibition of the high current density area by the additive, it can grow horizontally without causing the crystal to be too high in the longitudinal direction and easy to peel off; when the reverse current is turned on, due to the inhibition of the high current density area by the additive, the copper in the low current density area is preferentially dissolved, thereby expanding the surface height difference between the high area and the low area, thereby increasing the roughness of the coating.
[0007] The single-sided roughening process of the lead frame of the present application is "lead frame forming → degreasing → pickling → electroplating roughening → pickling". Compared with the "subtractive" process, it does not require special pre-treatment and post-treatment, which significantly shortens the electroplating production process of the lead frame and avoids additional production costs.
[0008] The single-sided roughening process of the lead frame of the present application is a single-sided roughening process. Through a specially designed electroplating device, it can ensure that only one side of the lead frame can be electroplated with a rough copper layer, while the surface of the other side is not electroplated, so its roughness will not be increased. In the single-sided packaging process of QFN and the like, which requires exposing the pad at the bottom of the package body, one side of the lead frame does not participate in the packaging and is not combined with the plastic sealant, so there is no risk of residual overflow glue. The design of the single-sided roughening process of the lead frame of the present application enables the roughening process to increase the bonding force between the packaging surface and the plastic sealant, and also retain the smooth surface of the non-plastic cover, avoiding increasing the difficulty of removing the overflow glue of the non-plastic cover, and significantly improving the matching degree of the single-sided roughening process of the lead frame with this type of packaging process.
[0009] The present application provides a single-side roughening process for a lead frame, which adopts the following technical solution: A single-side roughening process for a lead frame comprises the following steps: degreasing→pickling→electroplating roughening→pickling, wherein the electroplating roughening refers to obtaining an electroplated rough copper layer by electroplating in an electroplating tank loaded with electroplating rough copper solution in an electroplating device, wherein the electroplating rough copper solution comprises the following components: 220-270 g / L of copper sulfate, 50-80 g / L of pure sulfuric acid with a density of 1.84 g / mL, 80-120 ppm of chloride ions, and 0.5-0.7 g / L of additives.
[0010] Preferably, the additive is composed of polypropylene glycol, ethylene oxide-propylene oxide (EO-PO) block copolymer and sodium thiazoline disulfide propane sulfonate in a mass ratio of 6:5:4, the molecular weight of the polypropylene glycol is 20000-30000; the molecular weight of the ethylene oxide-propylene oxide (EO-PO) block copolymer is 10000-15000.
[0011] By adopting the above technical solution, the additive can adjust the secondary current distribution and inhibit the electrochemical reaction in the high current density area. When using bidirectional pulse current for electroplating, the forward current is close to the limiting current density, copper is rapidly deposited on the surface of the frame, and the crystal grows rapidly to form prismatic dendrites with dendrite characteristics. Due to the inhibition of the high current density area by the additive, it can grow horizontally without causing the crystal to be too high in the longitudinal direction and easy to peel off; when the reverse current is turned on, due to the inhibition of the high current density area by the additive, the copper in the low current density area is preferentially dissolved, thereby expanding the surface height difference between the high area and the low area, thereby increasing the roughness of the coating.
[0012] Preferably, the process conditions of the electroplating method are: the temperature of the electroplating crude copper solution is 30-50°C, bidirectional pulse current is used for electroplating, and the forward current density is 15-20A / dm 2 , power-on time 20ms, reverse current density 25-30A / dm 2 , the power-on time is 2ms and the electroplating time is 90-120s.
[0013] Preferably, when the thickness of the electroplated rough copper layer is 2 microns, the surface area of the electroplated rough copper layer is 1.5-2.5 times the surface area of the corresponding electroplated region of the lead frame.
[0014] Preferably, the electroplating method is to adopt a strip continuous electroplating mode, and the liquid level is controlled to the height of the lead frame through the discharge and overflow design to ensure that only the downward side of the lead frame will be plated with a rough copper layer.
[0015] Preferably, the electroplating device is divided into a medicine tank and an electroplating tank, the medicine tank and the electroplating tank are connected by a PP pipe, the electroplating crude copper medicine is pumped from the medicine tank to the electroplating tank by a water pump, and the electroplating crude copper medicine then flows back to the medicine tank from the electroplating tank through the PP pipe due to the height difference between the electroplating tank and the medicine tank, thereby forming a circulation and renewal of the electroplating crude copper medicine.
[0016] Preferably, the medicine tank is equipped with a temperature probe, a cooling coil and a hot water coil. The temperature is detected by the temperature probe, and the cooling coil and the hot water coil connected to the corresponding water source are used to cool down and heat up the electroplating copper medicine. The solenoid valve controls the renewal of the heat transfer medium in the coil. When the detected temperature does not match the set temperature, the solenoid valve of the corresponding coil is opened to update the internal heat transfer medium to cool or heat the electroplating copper medicine.
[0017] Preferably, the electroplating tank is divided into an inner tank and an outer tank, the inner tank is provided with a water inlet at the bottom, and the electroplating crude copper solution is pumped from the solution tank to the inner tank by a water pump for lead frame electroplating; the outer tank is provided with a water return port at the bottom, and the electroplating crude copper solution overflows to the outer tank and returns to the solution tank through a water return pipe.
[0018] Preferably, the inner tank is used as an electroplating device during the actual electroplating of the lead frame. The electroplating copper solution enters from the bottom water inlet, disperses the pressure through the water baffle and the water distribution plate, so that the pressure of the electroplating copper solution in each hole of the water plate is balanced, and the lead frame surface to be electroplated and roughened is submerged. An anode plate made of titanium alloy is arranged between the water plate and the lead frame position to form a loop with the lead frame. The lead frame surface to be electroplated and roughened faces downward. In addition, a current shielding device made of insulating material is arranged to shield the edge of the lead frame to average the current density of the lead frame as a whole; a series of rollers are arranged between the anode plate and the lead frame, and the rollers can further reduce the pressure of the electroplating copper solution, and the electroplating copper solution overflows from both ends of the rollers to the outer tank to ensure a lower liquid level in the inner tank; and the position where the lead frame enters and exits the inner tank can overflow the electroplating copper solution to ensure that the liquid level in the inner tank is not too high; drainage ports are opened at the bottom of both ends of the inner tank, and the liquid level in the inner tank is adjusted to the height of the lead frame by the height of the baffle.
[0019] In summary, the beneficial technical effects of this application are: 1. Increased surface area: After electroplating roughening, the surface area of the lead frame increases by more than 50%, and the contact area with the epoxy resin increases significantly, thereby improving the bonding strength and reliability of the package.
[0020] 2. Reduce production costs: The "additive" process does not require special electroplating pre-treatment and post-treatment, avoiding excessive production costs and simplifying the production process.
[0021] 3. Wide range of applications: The "additive" process does not require micro-etching of the copper surface. This process is not only suitable for commonly used copper alloys such as A194 and A192, but can also be used for iron-nickel alloy A94 and even metallized ceramic materials, with strong versatility.
[0022] 4. Environmentally friendly: The copper content of the roughening solution is controllable, and high-concentration wastewater will not be continuously produced, which reduces the loss of copper and is beneficial to wastewater treatment and environmental protection.
[0023] 5. Control the reaction process: Roughening is achieved through electroplating, and the reaction between the lead frame and the solution is controllable. It is not easy for the solution to splash or overflow, resulting in uneven roughening of the lead frame or poor appearance.
[0024] 6. Simple equipment modification: The use of single-sided electroplating roughening technology requires little adjustment to the lead frame electroplating production process. It only requires a simple modification of the electroplating equipment, and no mold is required.
[0025] 7. Reduce the defect rate: single-sided electroplating roughening is performed, the roughening area is reduced, the probability of defects occurring during the production process is reduced, and the difficulty of roughening lead frame production is reduced.
[0026] 8. Suitable for special packaging types: The lead frame with single-sided roughening will not make it difficult to remove the overflow glue during the packaging process due to the strong bonding between the non-packaging surface and the overflow glue, which will increase the difficulty of back-end production. It is very suitable for packaging types such as QFN that require exposed pads at the bottom of the component. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings used in the embodiments: Figure 1 This is a SEM image of the electroplated rough copper layer of the single-sided roughened lead frame prepared in Example 3 of the present application; Figure 2 This is a cross-sectional SEM image of the electroplated rough copper layer of the single-sided roughened lead frame prepared in Example 3 of the present application; Figure 3 A schematic diagram of the planar structure of the electroplating tank used in this application; Figure 4-Figure 7 A schematic diagram of the three-dimensional structure of the electroplating tank used in this application; Figure 8 It is a schematic diagram of the plastic package of a conventional double-sided roughened lead frame; Fig. 9 This is a schematic diagram of the QFN package type; Fig.10 This is a schematic diagram of a single-sided roughened plastic package body of the present application. DETAILED DESCRIPTION
[0028] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.
[0029] In the following embodiments, the electroplating device schematic diagram is shown in the attached Figure 3 -Attached Figure 7 As shown, the electroplating device is divided into a medicine tank and an electroplating tank, the medicine tank and the electroplating tank are connected by a PP pipe, and the electroplating crude copper medicine is pumped from the medicine tank to the electroplating tank by a water pump, and the electroplating crude copper medicine is then returned to the medicine tank from the electroplating tank through the PP pipe due to the height difference between the electroplating tank and the medicine tank, thereby forming the circulation and renewal of the electroplating crude copper medicine. The medicine tank is equipped with a temperature probe, a cooling coil and a hot water coil, and the temperature is detected by the temperature probe. The cooling coil and the hot water coil connected to the corresponding water source are used to cool and heat the electroplating crude copper medicine, and the electromagnetic valve controls the renewal of the heat transfer medium in the coil. When the detected temperature does not match the set temperature, the electromagnetic valve of the corresponding coil is opened to update the internal heat transfer medium to cool or heat the electroplating crude copper medicine. The electroplating tank is divided into an inner tank and an outer tank. The inner tank is provided with a water inlet at the bottom, and the electroplating crude copper solution is pumped from the solution tank to the inner tank by a water pump for lead frame electroplating. The outer tank is provided with a water return port at the bottom, and the electroplating crude copper solution overflows to the outer tank and returns to the solution tank through a water return pipe. The inner tank is used as an electroplating device during the actual electroplating of the lead frame. The electroplating crude copper solution enters from the bottom water inlet, and disperses the pressure through the water baffle and the water distribution plate, so that the pressure of the electroplating crude copper solution in each hole of the water plate is balanced, and the lead frame surface to be electroplated and roughened is submerged. An anode plate made of titanium alloy is arranged between the water plate and the lead frame position to form a loop with the lead frame. The lead frame surface to be electroplated and roughened faces downward. In addition, a current shielding device made of insulating material is arranged to shield the edge of the lead frame to average the current density of the lead frame as a whole; a series of rollers are arranged between the anode plate and the lead frame, and the rollers can further reduce the pressure of the electroplating crude copper solution, and the electroplating crude copper solution overflows from the two ends of the rollers to the outer tank to ensure a lower liquid level in the inner tank; and the position where the lead frame enters and exits the inner tank can overflow the electroplating crude copper solution to ensure that the liquid level in the inner tank is not too high; drainage ports are opened at the bottom of both ends of the inner tank, and the liquid level in the inner tank is adjusted to the height of the lead frame by the height of the baffle.
[0030] Oil removal process: ultrasonic oil removal is adopted, and the oil removal liquid includes the following components: sodium carbonate 25g / L, sodium hydroxide 25g / L, dimeroxy octylphenol ether 0.2g / L, triethanolamine 0.3g / L, temperature 50°C, oil removal time 2 minutes.
[0031] Pickling process: Pickling solution: 5 g / L pure sulfuric acid with a density of 1.84 g / mL, room temperature, time 30 s.
[0032] Example 1 A single-side roughening process for a lead frame comprises the following steps: degreasing → 2 water washing → pickling → 2 water washing → electroplating roughening → 2 water washing → pickling → 2 water washing → drying, wherein the electroplating roughening refers to obtaining an electroplated rough copper layer by electroplating in an electroplating tank loaded with electroplating rough copper solution in an electroplating device, wherein the electroplating rough copper solution comprises the following components: 220 g / L copper sulfate, 50 g / L pure sulfuric acid with a density of 1.84 g / mL, 80 ppm chloride ions, and 0. 5g / L, the additive consists of polypropylene glycol, ethylene oxide-propylene oxide (EO-PO) block copolymer and sodium thiazoline disulfide propane sulfonate in a mass ratio of 6:5:4, the molecular weight of the polypropylene glycol is 20000; the molecular weight of the ethylene oxide-propylene oxide (EO-PO) block copolymer is 10000, and the electroplating process conditions are: the electroplating crude copper solution temperature is 30°C, bidirectional pulse current is used for electroplating, and the forward current density is 20A / dm 2 , power-on time 20ms, reverse current density 30A / dm 2 The power-on time is 2ms, the electroplating time is 120s, and the electroplating method is to adopt a strip continuous electroplating mode. The liquid level is controlled to the height of the lead frame through the discharge and overflow design to ensure that only the downward side of the lead frame will be plated with a rough copper layer.
[0033] Example 2 A single-side roughening process for a lead frame comprises the following steps: degreasing → 2 water washing → pickling → 2 water washing → electroplating roughening → 2 water washing → pickling → 2 water washing → drying, wherein the electroplating roughening refers to obtaining an electroplated rough copper layer by electroplating in an electroplating tank loaded with electroplating rough copper solution in an electroplating device, wherein the electroplating rough copper solution comprises the following components: 270 g / L copper sulfate, 80 g / L pure sulfuric acid with a density of 1.84 g / mL, 120 ppm chloride ions, and 0.01% additive. .7g / L, the additive consists of polypropylene glycol, ethylene oxide-propylene oxide (EO-PO) block copolymer and sodium thiazoline disulfide propane sulfonate in a mass ratio of 6:5:4, the molecular weight of the polypropylene glycol is 30000; the molecular weight of the ethylene oxide-propylene oxide (EO-PO) block copolymer is 15000, and the electroplating process conditions are: the electroplating crude copper solution temperature is 50°C, bidirectional pulse current is used for electroplating, and the forward current density is 15A / dm 2 , power-on time 20ms, reverse current density 30A / dm 2The power-on time is 2ms, the electroplating time is 90s, and the electroplating method is to adopt a strip continuous electroplating mode. The liquid level is controlled to the height of the lead frame through the discharge and overflow design to ensure that only the downward side of the lead frame will be plated with a rough copper layer.
[0034] Example 3 A single-side roughening process for a lead frame comprises the following steps: degreasing → 2 water washings → pickling → 2 water washings → electroplating roughening → 2 water washings → pickling → 2 water washings → drying, wherein the electroplating roughening refers to obtaining an electroplated rough copper layer by electroplating in an electroplating tank loaded with electroplating rough copper solution in an electroplating device, wherein the electroplating rough copper solution comprises the following components: 240 g / L copper sulfate, 60 g / L pure sulfuric acid with a density of 1.84 g / mL, 100 ppm chloride ions, and 0.05 ppm additive. .6g / L, the additive is composed of polypropylene glycol, ethylene oxide-propylene oxide (EO-PO) block copolymer and sodium thiazoline disulfide propane sulfonate in a mass ratio of 6:5:4, the molecular weight of the polypropylene glycol is 26000; the molecular weight of the ethylene oxide-propylene oxide (EO-PO) block copolymer is 12000, and the electroplating process conditions are: the electroplating crude copper solution temperature is 40°C, bidirectional pulse current is used for electroplating, and the forward current density is 18A / dm 2 , power-on time 20ms, reverse current density 27A / dm 2 The power-on time is 2ms, the electroplating time is 105s, and the electroplating method adopts a strip continuous electroplating mode. The liquid level is controlled to the height of the lead frame through the discharge and overflow design to ensure that only the downward side of the lead frame will be plated with a rough copper layer.
[0035] Performance Testing The single-side roughened lead frames prepared in Examples 1 to 3 were respectively subjected to the following performance tests. The test results are shown in Table 1.
[0036] Roughness: The surface roughness Ra and Rz values were obtained by 3D laser microscope testing; Surface area multiple: the ratio of the surface area of the electroplated rough copper layer to the surface area of the corresponding lead frame electroplated. The surface area of the electroplated rough copper layer is tested by scanning electron microscopy (SEM) on the roughened electroplated rough copper layer surface of the lead frame.
[0037] Table 1 Performance test Analyzing the data in Table 1, we can see that: The single-sided roughened lead frame prepared in Example 1 to Example 3 has a surface area increased by more than 50% after electroplating roughening, and the contact area with the epoxy resin is significantly increased, thereby improving the bonding strength and reliability of the package.
[0038] Figure 1 This is a SEM image of the electroplated rough copper layer of the single-sided roughened lead frame prepared in Example 3 of the present application; Figure 2 This is a cross-sectional SEM image of the electroplated rough copper layer of the lead frame with single-side roughening prepared in Example 3 of the present application; Figure 1 and Figure 2 It can be seen that the surface roughness of the electroplated rough copper layer is higher and the grain distribution is more uniform.
[0039] The above embodiments are only used to explain the technical solutions of the present application rather than to limit them. Although the above embodiments provide a specific description of the present application, relevant technical personnel should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, and any modifications and equivalent replacements that do not depart from the spirit and scope of the present application should be included in the scope of protection of the present application.
Claims
1. A single-side roughening process for a lead frame, characterized in that: The method comprises the following steps: degreasing→pickling→electroplating roughening→pickling, wherein the electroplating roughening refers to obtaining an electroplated rough copper layer by electroplating in an electroplating tank loaded with electroplating rough copper solution in an electroplating device, wherein the electroplating rough copper solution comprises the following components: 220-270 g / L of copper sulfate, 50-80 g / L of pure sulfuric acid with a density of 1.84 g / mL, 80-120 ppm of chloride ions, and 0.5-0.7 g / L of additives.
2. A single-side roughening process for a lead frame according to claim 1, characterized in that: The additive consists of polypropylene glycol, ethylene oxide-propylene oxide (EO-PO) block copolymer and sodium thiazoline disulfide propane sulfonate in a mass ratio of 6:5:4, the molecular weight of the polypropylene glycol is 20000-30000; the molecular weight of the ethylene oxide-propylene oxide (EO-PO) block copolymer is 10000-15000.
3. A single-side roughening process for a lead frame according to claim 1, characterized in that: The process conditions of the electroplating method are: the temperature of the electroplating crude copper solution is 30-50°C, bidirectional pulse current is used for electroplating, and the forward current density is 15-20A / dm 2 , power-on time 20ms, reverse current density 25-30A / dm 2 , the power-on time is 2ms and the electroplating time is 90-120s.
4. The single-side roughening process of a lead frame according to claim 1, characterized in that: When the thickness of the electroplated rough copper layer is 2 microns, the surface area of the electroplated rough copper layer is 1.5-2.5 times the surface area of the corresponding electroplated region of the lead frame.
5. The single-side roughening process of a lead frame according to claim 1, characterized in that: The electroplating method adopts a strip continuous electroplating mode, and the liquid level is controlled to the height of the lead frame through the discharge and overflow design, ensuring that only the downward side of the lead frame will be plated with a rough copper layer.
6. The single-side roughening process of a lead frame according to claim 1, characterized in that: The electroplating device is divided into a medicine tank and an electroplating tank. The medicine tank and the electroplating tank are connected by a PP pipe. The electroplating crude copper medicine is pumped from the medicine tank to the electroplating tank by a water pump. The electroplating crude copper medicine then flows back to the medicine tank from the electroplating tank through the PP pipe due to the height difference between the electroplating tank and the medicine tank, thereby forming a circulation and renewal of the electroplating crude copper medicine.
7. A single-side roughening process for a lead frame according to claim 6, characterized in that: The medicine tank is provided with a temperature probe, a cooling coil and a hot water coil. The temperature is detected by the temperature probe, and the cooling coil and the hot water coil connected to the corresponding water source are used to cool down and heat up the electroplating crude copper medicine. The solenoid valve controls the renewal of the heat transfer medium in the coil. When the detected temperature does not match the set temperature, the solenoid valve of the corresponding coil is opened to update the internal heat transfer medium to cool or heat the electroplating crude copper medicine.
8. A single-side roughening process for a lead frame according to claim 6, characterized in that: The electroplating tank is divided into an inner tank and an outer tank. The inner tank is provided with a water inlet at the bottom, and the electroplating crude copper solution is pumped from the solution tank to the inner tank by a water pump for lead frame electroplating. The outer tank is provided with a water return port at the bottom, and the electroplating crude copper solution overflows to the outer tank and returns to the solution tank through a water return pipe.
9. A single-side roughening process for a lead frame according to claim 8, characterized in that: The inner tank is used as an electroplating device during the actual electroplating of the lead frame. The electroplating crude copper solution enters from the bottom water inlet, and disperses the pressure through the water baffle and the water distribution plate, so that the pressure of the electroplating crude copper solution in each hole of the water plate is balanced, and the lead frame surface to be electroplated and roughened is submerged. An anode plate made of titanium alloy is arranged between the water plate and the lead frame position to form a loop with the lead frame. The lead frame surface to be electroplated and roughened faces downward. In addition, a current shielding device made of insulating material is arranged to shield the edge of the lead frame to average the current density of the lead frame as a whole; a series of rollers are arranged between the anode plate and the lead frame, and the rollers can further reduce the pressure of the electroplating crude copper solution, and the electroplating crude copper solution overflows from the two ends of the rollers to the outer tank to ensure a lower liquid level in the inner tank; and the position where the lead frame enters and exits the inner tank can overflow the electroplating crude copper solution to ensure that the liquid level in the inner tank is not too high; drainage ports are opened at the bottom of both ends of the inner tank, and the liquid level in the inner tank is adjusted to the height of the lead frame by the height of the baffle.