Processing method for aluminum-based copper-clad plate of intelligent power module

Abstract

The invention relates to the technical field of intelligent power module machining, in particular to an intelligent power module aluminum-based copper-clad plate machining method which comprises the steps that cutting, etching, AOI detection, solder mask, CCD drilling, ET testing, nickel and gold immersion and V-CUT cutting treatment are conducted on a target aluminum-based copper-clad plate; the aluminum-based copper-clad plate subjected to V-CUT cutting is subjected to primary gold plate cleaning, and during gold plate cleaning, atmosphere plasma cleaning comprises cleaning of the aluminum-based copper-clad plate through mixed gas of argon and oxygen; the aluminum-based copper-clad plate subjected to primary gold plate cleaning is subjected to pressure resistance testing and finished product plate grinding, and secondary gold plate cleaning is carried out; and performing FQC inspection on the aluminum-based copper-clad plate subjected to secondary gold plate cleaning to finish processing. According to the invention, scraps and other dirt remaining on the surface can be effectively cleaned, the pollution problem of the power module in the production process is solved, the reliability of the power module is improved, and the packaging loss is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of intelligent power module processing, and in particular to a method for processing an aluminum-based copper-clad plate of an intelligent power module. Background Art

[0002] Intelligent Power Module (IPM) is an advanced power switch device that integrates power switch elements and high-voltage integrated drive circuits, and has built-in fault detection circuits such as overvoltage, overcurrent and overheating. Its core component is a high-speed, low-power IGBT (insulated gate bipolar transistor) chip, which combines the advantages of GTR (high-power transistor) and MOSFET (field effect transistor).

[0003] Aluminum-based copper-clad laminate is the substrate of the power module and has good thermal conductivity. Aluminum-based copper-clad laminate is made into the required graphic circuit substrate through etching process and is widely used in power modules, motor drive modules, automotive electronics, LED and other fields. For some special application environments, such as power module packaging, electrical connection is achieved by bonding wire on aluminum-based copper-clad laminate, and the wire types used in the bonding method are copper wire, aluminum wire and gold wire, so the processing requirements of aluminum-based circuit board are relatively high. In order to ensure that the binding wire meets the tensile requirements, the cleanliness of the circuit surface should be ensured as much as possible, and no pollution, incompleteness or pits are allowed. If there is any adverse situation, it will cause the plastic sealing of the power module to fail, and there will be problems such as decoupling (metal wire is bound to the PAD of aluminum-based copper-clad laminate) and delamination (poor bonding between plastic sealing material and aluminum-based copper-clad laminate), which will affect the reliability of the product. At present, the processing process of aluminum-based copper-clad laminate does not have cleaning process control after high-voltage testing. During high-voltage testing, metal flying probes need to be inserted into the aluminum-based copper-clad laminate circuit. During the working process of the equipment, there are organic matter or metal residues and metal chips falling on the surface of the aluminum-based copper-clad laminate. At the same time, there are two grinding steps in the process, which may introduce new impurities. If the grinding equipment is not cleaned properly, the residues of other materials previously ground or the debris of the abrasive itself may adhere to the surface of the aluminum-based copper clad laminate during the grinding process, causing new pollution and affecting product quality. Summary of the invention

[0004] The invention proposes a method for processing an aluminum-based copper-clad laminate for an intelligent power module, so as to solve the problem that surface pollution and low cleanliness of the aluminum substrate exist in the production process of the existing aluminum-based copper-clad laminate, which affects the product quality.

[0005] According to one aspect of the present invention, a method for processing an aluminum-based copper-clad laminate of an intelligent power module is provided, comprising:

[0006] The target aluminum-based copper-clad laminate is processed by cutting, etching, AOI inspection, solder mask, CCD drilling, ET testing, nickel-gold immersion and V-CUT cutting;

[0007] The aluminum-based copper-clad laminate after V-CUT cutting is cleaned once, wherein the gold plate cleaning includes: aluminum grinding, alkaline solution cleaning, acid solution cleaning and / or atmospheric plasma cleaning;

[0008] Wherein, the atmospheric plasma cleaning comprises: using a mixed gas of argon and oxygen to clean the aluminum-based copper-clad laminate;

[0009] The aluminum-based copper-clad laminate after the gold plate is cleaned once is subjected to a pressure resistance test and a finished product grinding test respectively;

[0010] Performing secondary gold plate cleaning on the aluminum-based copper-clad laminate after the finished plate is ground;

[0011] The aluminum-based copper-clad laminate after the secondary gold plate cleaning is subjected to FQC inspection to complete the processing.

[0012] Preferably, the cutting comprises:

[0013] Cutting the aluminum-based copper-clad laminate into a predetermined size;

[0014] Applying PUV film on the cut aluminum-based copper-clad laminate;

[0015] Drilling holes at predetermined positions on the aluminum-based copper-clad laminate after film application;

[0016] The drilled aluminum-based copper-clad laminate is subjected to dry film photo-imaging treatment.

[0017] Preferably, the etching comprises:

[0018] Prepare acidic and alkaline etching solutions, wherein the acidic etching solution comprises at least: copper chloride, hydrochloric acid and additives, and the alkaline etching solution comprises at least: copper ammonia complex, ammonium salt and additives;

[0019] Set the temperature, speed and pressure for acid and alkaline etching respectively;

[0020] The aluminum-based copper-clad laminate is subjected to acid etching and alkaline etching using the etching solution and according to the temperature, speed and pressure.

[0021] Preferably, the solder mask comprises:

[0022] Printing liquid solder resist ink on the aluminum-based copper-clad laminate by screen printing equipment;

[0023] Expose the screen-printed aluminum-based copper-clad laminate by ultraviolet light;

[0024] Putting the exposed aluminum-based copper-clad laminate into a developer for development;

[0025] The developed aluminum-based copper-clad laminate is subjected to a curing treatment.

[0026] Preferably, the ET test comprises:

[0027] Placing the aluminum-based copper-clad laminate on a bed-of-nails fixture that matches its pad layout;

[0028] Sending a test electrical signal to a test needle at one end of the bed of nails fixture through the tester;

[0029] If the tester receives the test signal from the test needle at the other end of the bed of nails fixture, the ET test of the aluminum-based copper-clad laminate passes.

[0030] Preferably, the nickel-gold immersion process comprises:

[0031] Degreasing the surface of the aluminum-based copper-clad laminate by using a degreasing agent;

[0032] Micro-etching the surface of the degreased aluminum-based copper-clad laminate using an acidic solution;

[0033] The aluminum-based copper-clad laminate after microetching is subjected to nickel plating, wherein the plating solution used for nickel plating comprises at least: nickel sulfate, nickel chloride, boric acid and additives;

[0034] The aluminum-based copper-clad plate after the nickel deposition is subjected to gold deposition, wherein the plating solution used for the gold deposition comprises at least potassium gold cyanide and additives.

[0035] Preferably, the alkaline solution cleaning comprises:

[0036] The alkaline solution is sodium hydroxide or sodium carbonate, the concentration of the alkaline solution is 3%-10%, the cleaning temperature is 40-70°C, and the cleaning time is 3-10 minutes;

[0037] The acid solution cleaning comprises:

[0038] The acid solution is dilute hydrochloric acid or dilute sulfuric acid, the concentration of the acid solution is 3%-8%, and the cleaning time is 2-6 minutes.

[0039] Preferably, the withstand voltage test includes:

[0040] Performing a DC withstand voltage test on the aluminum-based copper-clad laminate, wherein during the DC withstand voltage test, a DC voltage of 150% to 200% of the rated voltage is applied to the aluminum-based copper-clad laminate;

[0041] An AC withstand voltage test is performed on the aluminum-based copper-clad laminate. During the AC withstand voltage test, an AC voltage of 150% of the rated voltage is applied to the aluminum-based copper-clad laminate.

[0042] Preferably, the finished grinding plate comprises:

[0043] The aluminum-based copper-clad laminate is ground using abrasives with a particle size of 80-300 mesh, and the grinding pressure is 2-5 kg / cm 2 , the speed is 1000-2000 rpm.

[0044] Preferably, the FQC inspection includes:

[0045] If there are scratches and exposed copper on the aluminum-based copper-clad laminate, determine whether the scratch width is less than 0.1 mm, and / or the exposed copper area is in a non-critical area and does not exceed 0.25 mm 2 If yes, the aluminum-based copper clad laminate passes the FQC inspection.

[0046] The present invention has at least the following beneficial effects:

[0047] The present invention proposes a method for processing an aluminum-based copper-clad laminate for an intelligent power module. By adding a gold plate cleaning process during the production process of the aluminum-based copper-clad laminate, debris and other dirt remaining on the surface can be effectively cleaned, thereby solving the pollution problem of the power module during the production process, improving the reliability of the power module, and reducing packaging loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings herein are incorporated into and constitute a part of the specification. These drawings illustrate embodiments consistent with the present invention and, together with the specification, are used to explain the technical solutions of the present invention.

[0049] Figure 1 A production flow chart of an aluminum-based copper-clad laminate according to an embodiment of the present invention is shown;

[0050] Figure 2 An electrical topology diagram of an intelligent power module according to an embodiment of the present invention is shown;

[0051] Figure 3 A cross-sectional view of an intelligent power module according to an embodiment of the present invention is shown.

[0052] In the figure, 101 is a plastic packaging material layer, 102 is a copper foil layer, 103 is an insulating layer, 104 is a first aluminum-based surface oxide layer, 105 is an aluminum-magnesium complex, and 106 is a second aluminum-based surface oxide layer. DETAILED DESCRIPTION

[0053] Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0054] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0055] The term "and / or" herein is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C can represent including any one or more elements selected from the set consisting of A, B, and C.

[0056] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0057] Figure 1 A production flow chart of an aluminum-based copper-clad laminate according to an embodiment of the present invention is shown; Figure 2 An electrical topology diagram of an intelligent power module according to an embodiment of the present invention is shown; Figure 3 FIG. 2 shows a cross-sectional view of an intelligent power module according to an embodiment of the present invention. Figure 1-3 As shown, a method for processing aluminum-based copper-clad laminates for intelligent power modules comprises: cutting, etching, AOI inspection, solder mask, CCD drilling, ET testing, nickel-gold immersion and V-CUT cutting of target aluminum-based copper-clad laminates respectively; cleaning the aluminum-based copper-clad laminates after V-CUT cutting once, wherein the gold plate cleaning comprises: aluminum grinding, alkaline solution cleaning, acid solution cleaning and / or atmospheric plasma cleaning; wherein the atmospheric plasma cleaning comprises: cleaning the aluminum-based copper-clad laminates with a mixed gas of argon and oxygen; performing a withstand voltage test and finished product grinding on the aluminum-based copper-clad laminates after the first gold plate cleaning; performing a second gold plate cleaning on the aluminum-based copper-clad laminates after the finished product grinding; performing FQC inspection on the aluminum-based copper-clad laminates after the second gold plate cleaning to complete the processing.

[0058] In the embodiment of the present invention, Figure 2As shown, the intelligent power module 001 includes a control chip 002 and three inverter units. The inverter units include three groups of inverter modules. Each group of inverter modules includes two triode transistors, wherein 003 and 006 form a group, 004 and 007 form a group, and 005 and 008 form a group. Each group of two triode transistors is divided into an upper bridge arm and a lower bridge arm, wherein triode transistor 003 is an upper bridge arm, triode transistor 007 is a lower bridge arm, triode transistor 004 is an upper bridge arm, triode transistor 007 is a lower bridge arm, triode transistor 005 is an upper bridge arm, and triode transistor 008 is a lower bridge arm. The drain of the triode transistor 003 of the upper bridge arm is connected to the high voltage input terminal P of the module, the source of the triode transistor 003 of the upper bridge arm is connected to the drain of the triode transistor 006 of the lower bridge arm, and the lower bridge arm The source of the triode transistor 006 is connected to the module external pin UN, the gates of the two triode transistors are connected to the control chip 002, the source of the triode transistor 004 of the upper bridge arm is connected to the drain of the triode transistor 007 of the lower bridge arm, the source of the triode transistor 007 of the lower bridge arm is connected to the module external pin VN, the gates of the two triode transistors are connected to the control chip 002, the source of the triode transistor 005 of the upper bridge arm is connected to the drain of the triode transistor 008 of the lower bridge arm, the source of the triode transistor 008 of the lower bridge arm is connected to the module external pin WN, the gates of the two triode transistors are connected to the control chip 002, 009 is the control chip high-frequency filter capacitor, connected to VCC and COM, as close as possible to the output end of the control chip, and its function is to filter out high-frequency signals. 010 is a high-frequency filter capacitor, the purpose of which is to filter out the coupled signal of the line to avoid false triggering of the power module.

[0059] Figure 3 It is a cross-sectional view of a power module, in which 101 is a plastic encapsulation material layer, which has an electrical isolation function; 102 is a copper foil layer, which is etched into the required circuit; 103 is an insulating layer, the purpose of which is to electrically isolate the copper layer from the aluminum substrate layer; 104 is an oxide layer on the surface of the aluminum substrate (the first aluminum substrate surface oxide layer), the main component of which is aluminum dioxide (AL2O3), also known as an aluminum-based protective film, which can enhance corrosion resistance and wear resistance on the one hand, and increase the insulation withstand voltage of the aluminum surface on the other hand, and the process thickness is controlled at 5-10um; 105 is an aluminum-magnesium complex, and its thickness is controlled at 1.45-1.55mm; 106 is another surface oxide layer of the aluminum substrate (the second aluminum substrate surface oxide layer), the main component of which is aluminum dioxide (AL2O3), and its thickness is controlled at 5-10um.

[0060] In the present invention, the cutting includes: cutting the aluminum-based copper-clad laminate into a predetermined size; applying PUV film to the cut aluminum-based copper-clad laminate; drilling holes at predetermined positions on the film-applied aluminum-based copper-clad laminate; and performing dry film photo imaging on the drilled aluminum-based copper-clad laminate.

[0061] In an embodiment of the present invention, the process of cutting includes cutting: an aluminum-based copper-clad laminate is made of three raw materials, aluminum plate, epoxy resin or epoxy glass cloth bonding sheet, and copper foil, which are hot-pressed, and both sides of the aluminum surface are anodized and cut into substrate plates of a certain size according to an etching production line.

[0062] Film pasting: PUV protective film is pasted on the aluminum surface of the aluminum-based copper clad laminate to prevent the aluminum surface from being scratched during the production process.

[0063] Drilling: Drill necessary positioning holes according to the route design drawing requirements.

[0064] Dry film photoimaging: A dry film is applied on the copper, which can produce a polymerization reaction after being irradiated by ultraviolet rays to form a stable substance attached to the board surface, thereby achieving the function of blocking electroplating and etching.

[0065] Board inspection: Perform appearance inspection on the entire board with PET photosensitive film to prevent circuit etching errors.

[0066] In the present invention, the etching includes: preparing acidic and alkaline etching solutions, wherein the acidic etching solution includes at least copper chloride, hydrochloric acid and additives, and the alkaline etching solution includes at least copper ammine complex, ammonium salt and additives; setting the temperature, speed and pressure during acidic and alkaline etching respectively; and performing acidic etching and alkaline etching on the aluminum-based copper-clad laminate using the etching solution and according to the temperature, speed and pressure.

[0067] In the embodiment of the present invention, the aluminum-based copper-clad laminate is etched after cutting, and the etching mainly includes two methods: acid etching and alkaline etching.

[0068] Among them, in acid etching, the etching solution is mainly composed of copper chloride (CuCl2), hydrochloric acid (HCl) and additives. Copper chloride provides copper ions, hydrochloric acid is used to control acidity, and additives are used to improve the etching effect, such as accelerating etching and making the etching surface smoother.

[0069] Etching solution concentration: the concentration of cupric chloride is 1-2 mol / L, and the concentration of hydrochloric acid is 1.5-3 mol / L.

[0070] The etching temperature is between 40-60℃. The appropriate temperature can ensure the etching speed and quality. Too high a temperature may cause the etching solution to evaporate too quickly and the etching to be uneven; too low a temperature will slow down the etching speed.

[0071] The etching speed is 1-2μm / min. The etching speed is affected by factors such as etching solution concentration, temperature and nozzle pressure.

[0072] Nozzle pressure: The nozzle sprays the etching solution evenly on the surface of the aluminum-based copper-clad laminate. The pressure during spraying is 1-3kg / cm 2, ensure that the etching solution can effectively wash the surface of the copper foil, take away the reaction products, and make the etching proceed smoothly.

[0073] Among them, during alkaline etching, the etching solution is mainly composed of alkaline copper ammonia complex, [Cu(NH3)4]2+, and also contains ammonium salts, additives, etc.

[0074] Etching solution concentration: copper ion concentration is about 1-1.5 mol / L.

[0075] The etching temperature is 50-60°C.

[0076] Etching speed: Alkaline etching is slightly faster than acid etching, which is 2-3μm / min.

[0077] During the etching process, the etching liquid needs to be stirred properly to ensure the uniformity of etching. The stirring speed is generally 100-300 rpm to prevent local over-etching or under-etching.

[0078] After etching, the aluminum-based copper-clad laminate also needs to be cleaned. Use deionized water for cleaning, and the cleaning time is about 1-3 minutes to ensure that the residual etching solution is removed to avoid corrosion and other adverse effects on the aluminum-based copper-clad laminate.

[0079] In an embodiment of the present invention, AOI inspection is performed on the etched aluminum-based copper-clad laminate. The AOI inspection is mainly based on optical principles. An optical imaging system is used to obtain an image of the aluminum-based copper-clad laminate circuit board, and to detect whether the shape of the circuit on the image is complete and whether there is an open circuit (circuit breakage).

[0080] At the same time, we will verify whether the width of the line meets the predetermined width, that is, whether there is a problem of being too narrow or too wide.

[0081] In terms of line spacing, we will confirm whether the distance between lines meets the minimum safety distance to prevent short circuits.

[0082] If the line is complete, the width meets the predetermined width, and the line spacing is greater than the minimum safety spacing, the AOI inspection is qualified.

[0083] In the present invention, the solder mask includes: printing liquid solder mask ink on the aluminum-based copper-clad laminate by screen printing equipment; exposing the screen-printed aluminum-based copper-clad laminate by ultraviolet light; placing the exposed aluminum-based copper-clad laminate in a developer for development; and curing the developed aluminum-based copper-clad laminate.

[0084] In an embodiment of the present invention, the aluminum-based copper-clad laminate after AOI testing is subjected to solder mask treatment, specifically comprising: firstly, screen printing is performed. Firstly, liquid solder mask ink is printed on the aluminum-based copper-clad laminate through a screen printing device. The mesh number of the screen is generally 80-300 meshes, which determines the transfer amount of ink and the printing accuracy. The scraper pressure during printing is 3-7kg / cm 2 , to ensure that the ink is evenly transferred to the appropriate position on the aluminum-based copper-clad laminate through the screen. After printing, it is necessary to stand at room temperature for 10-30 minutes for preliminary leveling to allow the ink to be naturally evenly distributed.

[0085] Expose the aluminum-based copper-clad laminate after preliminary leveling. Use ultraviolet light (UV light) to irradiate the ink part that needs to be cured to undergo a photochemical reaction and cure. The exposure energy is 600-1200mJ / cm 2 The exposure time depends on the power of the exposure machine and the characteristics of the ink.

[0086] The exposed aluminum-based copper-clad laminate is placed in a developer to remove the unexposed and uncured ink. The main component of the developer is alkaline substances such as sodium carbonate, with a concentration of 1-2%. The developing temperature is controlled at 30-32°C, and the time is about 1-3 minutes. The parts that need to be welded, such as the pad, are exposed through development.

[0087] After development, the aluminum-based copper-clad laminate must be cured to allow the ink to fully solidify. The thermal curing method is used to bake at 150-160°C for 30-60 minutes to form a solid protective film for the solder mask ink.

[0088] In an embodiment of the present invention, CCD drilling is performed on the aluminum-based copper-clad laminate that has passed the AOI test. The CCD drilling includes: taking an image of the aluminum-based copper-clad laminate by a CCD camera, so that the target position of the drilling can be accurately identified, and the accuracy can reach about ±0.025mm. The drilling equipment uses a high-speed spindle motor with a very high speed. For drilling of small apertures, the speed is 100,000-300,000 rpm. The drill bit diameter has a variety of sizes according to the design requirements of the aluminum-based copper-clad laminate, such as 0.1mm-0.5mm.

[0089] In the present invention, the ET test includes: placing the aluminum-based copper-clad laminate on a needle bed fixture that matches its pad layout; sending a test electrical signal to a test needle at one end of the needle bed fixture through a tester; if the tester receives a test signal from the test needle at the other end of the needle bed fixture, the ET test of the aluminum-based copper-clad laminate passes.

[0090] In the embodiment of the present invention, the aluminum-based copper-clad laminate after CCD drilling is subjected to an ET test, and the ET test is mainly to check whether the circuit on the aluminum-based copper-clad laminate is disconnected. An electrical signal is applied at one end of the circuit board, and then the other end is tested to see whether the signal can be received. If it cannot be received, it indicates that the circuit is open, that is, the circuit is interrupted.

[0091] Make a bed of needles fixture that matches the pad layout of the aluminum-based copper-clad laminate. During the test, the aluminum-based copper-clad laminate is placed on the bed of needles, and the pads are contacted by the test needles. The tester sends and receives test signals to the test needles to detect open and short circuit conditions. The manufacturing accuracy of the bed of needles is high, and the spacing accuracy of the test needles is within ±0.05mm.

[0092] In the present invention, the nickel-gold plating includes: degreasing the surface of the aluminum-based copper-clad laminate by using a degreasing agent; micro-etching the surface of the aluminum-based copper-clad laminate after degreasing by using an acidic solution; plating nickel on the aluminum-based copper-clad laminate after the micro-etching, wherein the plating solution components used during the nickel plating include at least: nickel sulfate, nickel chloride, boric acid and additives; plating gold on the aluminum-based copper-clad laminate after the nickel plating, wherein the plating solution components used during the gold plating include at least: potassium gold cyanide and additives.

[0093] In the embodiment of the present invention, the aluminum-based copper-clad laminate after the ET test is subjected to nickel-gold immersion, which is a surface treatment process, the main purpose of which is to deposit nickel and gold on the copper surface of the aluminum-based copper-clad laminate to enhance the solderability, corrosion resistance and wear resistance of the aluminum-based copper-clad laminate. The specific process includes:

[0094] Degreasing: Remove oil and impurities from the surface of the aluminum-based copper clad laminate, usually using an alkaline degreasing agent and treating at a temperature of 40-60°C for 3-5 minutes to ensure a clean surface and provide a good foundation for the subsequent deposition process.

[0095] Micro-etching: Use an acid solution (such as sodium persulfate, etc.) to micro-etch the copper surface, causing slight corrosion on the copper surface, creating a microscopic rough surface, and enhancing the bonding strength between the nickel layer and the copper layer. The concentration of the micro-etching solution is 60-100g / L, and the micro-etching time is about 30-60 seconds.

[0096] Pre-dip: This is a transition step in which the aluminum-based copper-clad laminate is immersed in an acidic solution (such as sulfuric acid) to prevent the introduction of impurities and adjust the surface state. The pre-dip time is short, about 10-30 seconds.

[0097] Nickel deposition: The main components of the plating solution include nickel sulfate (NiSO4), nickel chloride (NiCl2), boric acid (H3BO3) and additives. Nickel sulfate is the main source of nickel ions, nickel chloride is used to improve the conductivity of the plating solution, boric acid plays a buffering role, and additives are used to improve the quality of nickel plating, such as making the nickel layer more uniform. Plating solution concentration: nickel sulfate concentration is 250-350g / L, nickel chloride concentration is 40-60g / L, and boric acid concentration is 30-40g / L. Temperature and pH value: The temperature of nickel plating is 80-90℃, and the pH value is maintained between 4.2-4.8. Appropriate temperature and pH value are conducive to the deposition of nickel, ensuring the quality and deposition speed of the nickel layer. The deposition speed, that is, the nickel deposition time, is 1-2μm / h. The stirring method adopts mechanical stirring or air stirring to evenly distribute the nickel ions in the plating solution and prevent local nickel deposition from being too thick. The stirring speed is 100-300 rpm.

[0098] Gold immersion: The main components of the plating solution are potassium gold cyanide (KAu(CN)2) and additives. Potassium gold cyanide provides gold ions, and additives are used to control the gold deposition process, such as making the gold layer brighter. Plating solution concentration: The concentration of potassium gold cyanide is usually 1-3g / L. Temperature and pH value: The gold immersion temperature is 80-90℃, and the pH value is 4.5-5.0. The gold deposition speed is relatively slow, and the gold immersion time is 0.05-0.15μm / h. Stirring method: Proper stirring is also required to ensure uniform deposition of the gold layer, and the stirring speed is similar to that of nickel immersion.

[0099] In an embodiment of the present invention, V-CUT cutting is performed on the aluminum-based copper-clad laminate after nickel-gold deposition. V-CUT mainly cuts a V-shaped groove on the surface of the aluminum-based copper-clad laminate. During the production process, when a large aluminum-based copper-clad laminate contains multiple small aluminum-based copper-clad laminate units, the use of the V-Cut process can facilitate subsequent separation operations. During cutting, the tool rotates at a high speed of 20,000-40,000 rpm to cut the aluminum-based copper-clad laminate along a pre-designed cutting path. The cutting depth is usually 1 / 3-1 / 2 of the thickness of the aluminum-based copper-clad laminate.

[0100] In the present invention, the alkaline solution cleaning includes: the alkaline solution is sodium hydroxide or sodium carbonate, the alkaline solution concentration is 3%-10%, the cleaning temperature is 40-70°C, and the cleaning time is 3-10 minutes; the acidic solution cleaning includes: the acidic solution is dilute hydrochloric acid or dilute sulfuric acid, the acidic solution concentration is 3%-8%, and the cleaning time is 2-6 minutes.

[0101] In the embodiment of the present invention, the gold plate cleaning can remove various pollutants remaining on the aluminum-based copper-clad laminate during the manufacturing process, such as oil, flux, etching solution, dust and particles. These pollutants may cause short circuits, corrosion, reduced insulation performance and other problems. Gold plate cleaning includes alkaline cleaning, acid cleaning and atmospheric plasma cleaning.

[0102] Among them, alkaline cleaning is to use alkaline solutions (such as sodium hydroxide, sodium carbonate, etc.) to remove oil and some organic pollutants. The concentration of the solution is 3%-10%, the cleaning temperature is 40-70℃, and the cleaning time is 3-10 minutes. During the cleaning process, it can be stirred appropriately at a speed of 50-150 rpm to allow the cleaning solution to better contact the pollutants and enhance the cleaning effect.

[0103] Acid cleaning is mainly used to remove metal oxides and some alkaline residues. The acid solution uses dilute hydrochloric acid or dilute sulfuric acid with a concentration of 3%-8% and a cleaning time of 2-6 minutes.

[0104] After acid cleaning, the aluminum-based copper clad laminate needs to be thoroughly rinsed with clean water to prevent acid residue.

[0105] When performing atmospheric plasma cleaning, the aluminum-based copper-clad laminate is placed in a cleaning machine, and a mixed gas of argon and oxygen is sprayed from a spray gun of the cleaning machine to wash the surface of the aluminum-based copper-clad laminate. The parameters set during cleaning can be:

[0106] The cleaning pressure is 10-100 Pa; the time is 120 s, 180 s or 240 s; the argon content is 50 sccm; the oxygen content is 20 sccm.

[0107] The surface cleanliness of the substrate treated with argon + oxygen mixed gas is better, the metal wire binding effect is better, and the bonding force between the plastic packaging material and the aluminum substrate is enhanced.

[0108] In the present invention, the voltage withstand test includes: performing a DC voltage withstand test on the aluminum-based copper clad laminate, during which a DC voltage of 150%-200% of the rated voltage is applied to the aluminum-based copper clad laminate; performing an AC voltage withstand test on the aluminum-based copper clad laminate, during which an AC voltage of 150% of the rated voltage is applied to the aluminum-based copper clad laminate.

[0109] In an embodiment of the present invention, a withstand voltage test is performed on the aluminum-based copper-clad laminate after the gold plate is cleaned. The withstand voltage test is to ensure safety, verify that the insulating material and structural design meet the standards, prevent insulation failures from causing dangerous accidents, prevent breakdown, detect whether the insulation distance is sufficient, and avoid breakdown damage to the circuit board under high voltage.

[0110] The voltage selection during the test is: the voltage during the DC withstand voltage test is 150%-200% of the rated voltage, which is adjusted according to the actual situation. The voltage during the AC withstand voltage test is 150% of the rated voltage, and the test time is 1 minute.

[0111] In the present invention, the finished grinding plate comprises: grinding the aluminum-based copper-clad plate with a grinding material having a particle size of 80-300 mesh, and a grinding pressure of 2-5 kg / cm2 , the speed is 1000-2000 rpm.

[0112] In an embodiment of the present invention, the aluminum-based copper-clad laminate is ground after the pressure resistance test, and a suitable abrasive is selected according to the characteristics of the aluminum-based copper-clad laminate and the grinding requirements. The size of the abrasive particles is critical. For example, for fine grinding with high surface requirements, a finer abrasive is selected, and the particle size is about 100-300 mesh; if it is coarse grinding, the particles can be 80-100 mesh. After the board enters the grinding machine, it is first coarsely ground. The purpose of coarse grinding is to quickly remove larger surface defects, oxide layers, etc. At this time, the grinding wheel will contact the board with a certain pressure, and the specific pressure is 2-5kg / cm 2 The grinding wheel rotates at a high speed of 1000-2000 rpm, and the surface of the board is initially flattened through the friction between the abrasive particles and the board surface.

[0113] In an embodiment of the present invention, the aluminum-based copper-clad laminate after grinding treatment is subjected to secondary gold plate cleaning, and the secondary gold plate cleaning process is the same as the primary gold plate cleaning process, that is, alkaline solution cleaning, acid solution cleaning and atmospheric plasma cleaning are performed in sequence.

[0114] In the present invention, the FQC inspection includes: if there are scratches and exposed copper on the aluminum-based copper-clad laminate, determine whether the scratch width is less than 0.1 mm, and / or the exposed copper area is in a non-critical area and does not exceed 0.25 mm 2 If yes, the aluminum-based copper clad laminate passes the FQC inspection.

[0115] In the embodiment of the present invention, check whether the surface of the aluminum-based copper-clad laminate has scratches, bruises, exposed copper, oxidation, etc. For example, if a slight scratch does not affect the circuit function, the width should be less than 0.1mm; the exposed copper area in a non-critical area should not exceed 0.25mm 2 .

[0116] Check the color and cleanliness of the aluminum-based copper-clad laminate, that is, check whether the color of the board surface is uniform, and whether there are stains such as oil, fingerprints, and residual chemicals.

[0117] FQA random inspection is carried out on the aluminum-based copper clad laminates after FQC inspection. Random inspection is the last checkpoint in the production quality control of aluminum-based copper clad laminates. It ensures that the product quality meets the established quality standards before delivery, evaluates the quality level of the entire batch of aluminum-based copper clad laminate products from a macro perspective, and ensures that only qualified products can enter the market.

[0118] The aluminum-based copper clad laminates after FQC inspection are packaged and stored, thus completing the aluminum-based copper clad laminate processing process.

[0119] It can be understood that the above-mentioned various method embodiments mentioned in the present invention can be combined with each other to form a combined embodiment without violating the principle logic. Due to space limitations, the present invention will not go into details.

[0120] Those skilled in the art will appreciate that, in the above method of specific implementation, the order in which the steps are written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of the steps should be determined by their functions and possible internal logic.

[0121] The process flow of the intelligent power module aluminum-based copper-clad laminate processing method proposed in the present invention is: cutting → etching circuit → AOI inspection → solder mask → drilling → ET test → nickel-gold immersion → V-CUT (protective film) → primary gold plate cleaning → voltage resistance test → finished product grinding → secondary gold plate cleaning → FQC inspection → FQA sampling inspection → packaging → warehousing. The two gold plate cleanings can further improve the cleanliness control of the aluminum-based copper-clad laminate, and effectively solve the process problems caused by the green oil surface and PAD surface contamination of the aluminum-based copper-clad laminate in the power module packaging. Improve the reliability of the power module and reduce the packaging loss.

[0122] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for processing an aluminum-based copper-clad laminate for an intelligent power module, characterized in that: include: The target aluminum-based copper-clad laminate is processed by cutting, etching, AOI inspection, solder mask, CCD drilling, ET testing, nickel-gold immersion and V-CUT cutting; The aluminum-based copper-clad laminate after V-CUT cutting is cleaned once, wherein the gold plate cleaning includes: aluminum grinding, alkaline solution cleaning, acid solution cleaning and / or atmospheric plasma cleaning; Wherein, the atmospheric plasma cleaning comprises: using a mixed gas of argon and oxygen to clean the aluminum-based copper-clad laminate; The aluminum-based copper-clad laminate after the gold plate is cleaned once is subjected to a pressure resistance test and a finished product grinding test respectively; Performing secondary gold plate cleaning on the aluminum-based copper-clad laminate after the finished plate is ground; The aluminum-based copper-clad laminate after the secondary gold plate cleaning is subjected to FQC inspection to complete the processing.

2. The method for processing aluminum-based copper-clad laminates for intelligent power modules according to claim 1, characterized in that: The cutting process comprises: Cutting the aluminum-based copper-clad laminate into a predetermined size; Applying PUV film on the cut aluminum-based copper-clad laminate; Drilling holes at predetermined positions on the aluminum-based copper-clad laminate after film application; The drilled aluminum-based copper-clad laminate is subjected to dry film photo-imaging treatment.

3. The method for processing aluminum-based copper-clad laminates for intelligent power modules according to claim 1, characterized in that: The etching comprises: Prepare acidic and alkaline etching solutions, wherein the acidic etching solution comprises at least: copper chloride, hydrochloric acid and additives, and the alkaline etching solution comprises at least: copper ammine complex, ammonium salt and additives; Set the temperature, speed and pressure for acid and alkaline etching respectively; The aluminum-based copper-clad laminate is subjected to acid etching and alkaline etching using the etching solution and according to the temperature, speed and pressure.

4. The method for processing aluminum-based copper-clad laminates for intelligent power modules according to claim 1, characterized in that: The solder mask comprises: Printing liquid solder resist ink on the aluminum-based copper-clad laminate by screen printing equipment; Expose the screen-printed aluminum-based copper-clad laminate by ultraviolet light; Putting the exposed aluminum-based copper-clad laminate into a developer for development; The developed aluminum-based copper-clad laminate is subjected to a curing treatment.

5. The method for processing aluminum-based copper-clad laminate for intelligent power module according to claim 1, characterized in that: The ET tests include: Placing the aluminum-based copper-clad laminate on a bed-of-nails fixture that matches its pad layout; Sending a test electrical signal to a test needle at one end of the bed of nails fixture through the tester; If the tester receives the test signal from the test needle at the other end of the bed of nails fixture, the ET test of the aluminum-based copper-clad laminate passes.

6. The method for processing aluminum-based copper-clad laminates for intelligent power modules according to claim 1, characterized in that: The nickel-gold immersion comprises: Degreasing the surface of the aluminum-based copper-clad laminate by using a degreasing agent; Micro-etching the surface of the degreased aluminum-based copper-clad laminate using an acidic solution; The aluminum-based copper-clad laminate after microetching is subjected to nickel plating, wherein the plating solution used for nickel plating comprises at least: nickel sulfate, nickel chloride, boric acid and additives; The aluminum-based copper-clad plate after the nickel deposition is subjected to gold deposition, wherein the plating solution used for the gold deposition comprises at least potassium gold cyanide and additives.

7. The method for processing aluminum-based copper-clad laminates for intelligent power modules according to claim 1, characterized in that: The alkaline solution cleaning comprises: The alkaline solution is sodium hydroxide or sodium carbonate, the concentration of the alkaline solution is 3%-10%, the cleaning temperature is 40-70°C, and the cleaning time is 3-10 minutes; The acid solution cleaning comprises: The acid solution is dilute hydrochloric acid or dilute sulfuric acid, the concentration of the acid solution is 3%-8%, and the cleaning time is 2-6 minutes.

8. The method for processing aluminum-based copper-clad laminates for intelligent power modules according to claim 1, characterized in that: The withstand voltage test includes: Performing a DC withstand voltage test on the aluminum-based copper-clad laminate, wherein during the DC withstand voltage test, a DC voltage of 150% to 200% of the rated voltage is applied to the aluminum-based copper-clad laminate; An AC withstand voltage test is performed on the aluminum-based copper-clad laminate. During the AC withstand voltage test, an AC voltage of 150% of the rated voltage is applied to the aluminum-based copper-clad laminate.

9. The method for processing aluminum-based copper-clad laminates for intelligent power modules according to claim 1, characterized in that: The finished grinding plate comprises: The aluminum-based copper-clad laminate is ground using abrasives with a particle size of 80-300 mesh, and the grinding pressure is 2-5 kg / cm 2 , the speed is 1000-2000 rpm.

10. The method for processing an aluminum-based copper-clad laminate for an intelligent power module according to any one of claims 1 to 9, characterized in that: The FQC inspection includes: If there are scratches and exposed copper on the aluminum-based copper-clad laminate, determine whether the scratch width is less than 0.1 mm, and / or the exposed copper area is in a non-critical area and does not exceed 0.25 mm 2 If yes, the aluminum-based copper clad laminate passes the FQC inspection.

Images