Manufacturing process of LED thermoelectric separation aluminum substrate

Abstract

The application discloses a manufacturing process of an LED thermoelectric separation aluminum substrate, and relates to the technical field of LED thermoelectric separation aluminum substrates for new energy vehicles. The manufacturing process comprises the following steps: S1, cutting; S2, first manufacturing a copper-aluminum composite plate, pasting a dry film for etching, and forming a local boss; S3, making a GTL layer circuit of an FR-4 substrate, pasting a dry film negative for etching; S4, pasting pure glue on the FR-4 substrate after brownization and compacting by a film pressing machine; S5, drilling corresponding target holes according to a target of the FR-4 substrate design; S6, window processing of the FR-4 substrate corresponding to the boss area; S7, arranging and pressing the FR-4 substrate, the copper-aluminum composite plate and a buffer layer to form a plate part; S8, drilling the pressed plate part; S9, making an outer layer solder resist and surface treatment; and S10, electrical measurement and forming. The LED thermoelectric separation aluminum substrate manufactured by the manufacturing process has greatly enhanced LED heat dissipation capacity, directly prolonging the LED illumination time and service life.

Description

Technical Field

[0001] The present invention relates to the field of LED thermoelectric separation aluminum substrate technology for new energy vehicles, and in particular to a manufacturing process of an LED thermoelectric separation aluminum substrate. Background Art

[0002] New energy vehicles and high-power charging stations all require light-emitting diodes. As a new generation of solid-state light sources, light-emitting diodes (LEDs) have many advantages, such as long life, high efficiency, energy saving, and environmental protection. They are widely used in the field of display lighting. With the development of science and technology, advanced technologies are constantly being applied to semiconductor production, which has continuously improved the luminous efficiency of LEDs and continuously reduced their costs. The core part of the LED is the PN junction. When injected electrons and holes recombine at the PN junction, electrical energy is directly converted into light energy. However, not all of the converted light energy is emitted outside the LED. It is converted into heat energy by the absorber inside the PN junction and epoxy resin / silicone. Figure 1 As shown in the figure, this heat energy has a huge side effect on the lamp. If the heat cannot be effectively dissipated, the internal temperature of the LED will rise. The higher the temperature, the lower the LED's luminous efficiency and the shorter the LED's lifespan. In severe cases, it can cause the LED chip to fail immediately. Therefore, heat dissipation is still a huge obstacle to the application of high-power LEDs.

[0003] Existing heat dissipation technology: The heat generated by the PN junction of the LED passes through the LED base, solder paste welding layer, copper coating layer, insulation layer, aluminum plate, thermal conductive silicone gasket / silicone grease, heat dissipation aluminum profile, and then dissipates into the air, thus completing the heat dissipation process. Figure 1 As shown in the figure, the thermal conductivity of the LED base is about 80W / mk; the thermal conductivity of the solder paste welding layer is greater than 60W / mk; the thermal conductivity of the copper layer is about 400W / mk, the thermal conductivity of the aluminum plate and aluminum profile is about 200W / mk, the thermal conductivity of the insulation layer is about 1W / mk, and the thermal conductive silicone gasket / silicone grease is about SW / mk. However, the closer to the PN junction of the LED, the higher the heat flux density, and the thermal conductive silicone sheet / silicone grease has the aluminum plate to conduct heat horizontally and evenly, so the heat flux density of the insulation layer is much higher than that of the thermal conductive silicone gasket / silicone grease. Therefore, in summary, it can be clearly seen that the heat dissipation bottleneck lies in the insulation layer of the aluminum substrate. In view of this situation, it is urgent to develop a manufacturing process for LED thermoelectric separation aluminum substrate to meet the needs of actual use. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies in the prior art, and its main purpose is to provide a manufacturing process for an LED thermoelectric separation aluminum substrate. The LED thermoelectric separation aluminum substrate manufactured by adopting the manufacturing process for an LED thermoelectric separation aluminum substrate provided by the present application greatly enhances the heat dissipation capacity of the LED, directly extending the LED lighting time and service life; the manufacturing process for an LED thermoelectric separation aluminum substrate provided by the present application solves the current technical bottleneck and is suitable for the manufacture of new automotive LED thermoelectric separation aluminum substrates.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A process for manufacturing an LED thermoelectric separation aluminum substrate comprises the following steps:

[0007] S1. Cut FR-4 substrate, copper-aluminum composite board and pure glue respectively;

[0008] S2, first make a copper-aluminum composite plate, apply dry film etching, and form a local boss;

[0009] Make GTL layer circuit on S3 and FR-4 substrate, and etch with dry film negative;

[0010] S4, FR-4 substrate is browned and then coated with pure glue and compacted by laminator: copper-aluminum composite board is browned with browning liquid after the boss is etched;

[0011] S5. Drill corresponding target holes according to the target designed for the FR-4 substrate;

[0012] S6. Window processing is performed on the FR-4 substrate corresponding to the boss area, and the compensation value of the window area is reasonably compensated: pure glue is applied to the FR-4 substrate and grooves are formed, and then the FR-4 bare board is superimposed and pressed. The distance of the overflow glue is measured by slicing to determine the actual overflow glue amount and the engineering compensation coefficient. The compensation data of the pure glue groove is 0.1-0.2mm larger than the single side of the boss.

[0013] S7. Lay out and press the FR-4 substrate, copper-aluminum composite board and buffer layer to form a board: the initial temperature of pure glue pressing is 110-130℃, and press the combined board to be pressed;

[0014] S8, drilling the pressed plates;

[0015] S9, do outer layer solder mask and surface treatment;

[0016] S10, electrical testing and forming.

[0017] As a preferred solution: in step S7, a press is used for pressing, the pressure applied by the press is controlled to be 30-40kgf / cm², the pressing temperature of the pure glue is 110-160℃, the heating rate is controlled within 2-3℃ / min, and the temperature and pressure time is maintained for more than 90min.

[0018] As a preferred solution: the buffer layer in step S7 includes an upper release film located at the upper layer, a silicone sheet located at the middle layer, and a lower release film located at the lower layer.

[0019] As a preferred solution: in step S4, the browning is to micro-etch the copper surface of the copper-aluminum composite plate using H2O2 and H2SO4, and the organic additives in the browning solution react with the copper surface to form a layer of organic metal conversion film, which is embedded in the copper surface to form a grid-like conversion layer between the copper surface and the resin.

[0020] As a preferred solution: in step S2, the copper-aluminum composite plate is a copper-aluminum composite plate containing 15% copper, and a 155-165 μm copper layer is etched to make the boss, and the copper layer of the copper-aluminum composite plate is etched step by step with the copper layer facing downward.

[0021] As a preferred solution: in step S2, the specific steps of etching the copper-aluminum composite plate with the copper layer facing downward are: first, etching at a line speed of 3.0 m / min to etch a copper thickness of 90 μm; second, etching at a line speed of 2.4 m / min to etch 60 μm.

[0022] As a preferred solution: the LED thermal and electrical separation aluminum substrate includes L1 layer, L2 layer, L3 layer and L4 layer distributed in layers from top to bottom, the L1 layer and L2 layer are FR-4 substrates, the L3 layer and L4 layer form a copper-aluminum composite plate, the L3 layer is a copper layer, the L4 layer is an aluminum layer, and the boss is located in the middle of the L3 layer.

[0023] As a preferred solution: in step S7, the FR-4 substrate, the copper-aluminum composite board and the buffer layer are arranged and pressed to form a board. The specific steps are: first, the copper-aluminum composite board is browned, and after cooling, the aluminum layer protective film needs to be torn off, and the release film of the pure adhesive surface is torn off, and combined with the L3 layer of the copper-aluminum composite board, the board is firmly glued to fix the four corners, and the buffer layer is used instead of the copper foil, and the board is double-assembled.

[0024] As a preferred solution, the step S4 of applying the pure adhesive is as follows: first, the pure adhesive release paper is torn off, and then the adhesive is applied to the bottom surface of the FR-4 substrate in a straight direction, and the adhesive is passed through a thermoforming machine once, and the temperature of the thermoforming machine needs to be raised to 110°C.

[0025] As a preferred solution: in step S6, the gong groove is a gong boss fitting groove, and a double-edged milling cutter is used when gong the groove to reduce burr residue.

[0026] Compared with the existing technology, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical scheme that by adopting the production process of the LED thermoelectric separation aluminum substrate provided by the present application, the problem of bubbles in the non-flowing pure glue pressing plate is solved, the depression around the convex copper (boss position) is controlled, and the bonding strength between the pure glue and the FR-4 substrate and the copper layer is guaranteed; the LED thermoelectric separation aluminum substrate produced by the production greatly enhances the heat dissipation capacity of the LED, directly extending the LED lighting time and service life; the Lianzhi pure glue pressing technology, metal substrate etching convex copper technology, pure glue CNC cutting technology, covering film protection technology, dynamic area window opening technology, metal base molding technology, etc. are adopted to solve the current technical bottleneck, which is suitable for the production of new automotive LED thermoelectric separation aluminum substrates.

[0027] To more clearly illustrate the structural features and effects of the present invention, it is described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of LED heat dissipation model in the prior art of the present invention;

[0029] Figure 2 This is a diagram of the LED light-to-heat energy conversion mechanism of the present invention;

[0030] Figure 3 This is a schematic diagram of the heat conduction effect of LEDs according to the present invention;

[0031] Figure 4 A schematic diagram of pressure application during the pressing process of the present invention;

[0032] Figure 5 Schematic diagram of the structure of the buffer layer material of the present invention;

[0033] Figure 6 This is a pure adhesive lamination parameter curve diagram of the present invention;

[0034] Figure 7 This is a schematic diagram of the gong slot control of the present invention;

[0035] Figure 8 Schematic diagram of the browning of the copper layer of the present invention;

[0036] Figure 9 This is a schematic diagram of the structure of the LED thermal and electrical separation aluminum substrate of the present invention;

[0037] Figure 10 This is a process flow chart of manufacturing the LED thermal and electrical separation aluminum substrate in Example 1 of the present invention;

[0038] Figure 11 This is a first-view test result of the LED thermal and electrical separation aluminum substrate of the present invention;

[0039] Figure 12 This is a second-angle view of the glue overflow test effect of the LED thermal and electrical separation aluminum substrate of the present invention. DETAILED DESCRIPTION

[0040] The present invention Figure 2 As shown in FIG12 , a process for manufacturing an LED thermal and electrical separation aluminum substrate includes the following steps:

[0041] S1. Cut FR-4 substrate, copper-aluminum composite board and pure glue respectively;

[0042] S2, first make a copper-aluminum composite plate, apply dry film etching, and form a local boss;

[0043] Make GTL layer circuit on S3 and FR-4 substrate, and etch with dry film negative;

[0044] S4, FR-4 substrate is browned and then coated with pure glue and compacted by laminator: copper-aluminum composite board is browned with browning liquid after the boss is etched;

[0045] S5. Drill corresponding target holes according to the target designed for the FR-4 substrate;

[0046] S6. Window processing is performed on the FR-4 substrate corresponding to the boss area, and the compensation value of the window area is reasonably compensated: pure glue is applied to the FR-4 substrate and grooves are formed, and then the FR-4 bare board is superimposed and pressed. The distance of the overflow glue is measured by slicing to determine the actual overflow glue amount and the engineering compensation coefficient. The compensation data of the pure glue groove is 0.1-0.2mm larger than the single side of the boss.

[0047] S7. Lay out and press the FR-4 substrate, copper-aluminum composite board and buffer layer to form a board: the initial temperature of pure glue pressing is 110-130℃, and press the combined board to be pressed;

[0048] S8, drilling the pressed plates;

[0049] S9, do outer layer solder mask and surface treatment;

[0050] S10, electrical testing and forming.

[0051] In step S7, a press is used for lamination, and the pressure applied by the press is controlled to be 30-40 kgf / cm², the lamination temperature of the pure adhesive is 110-160°C, the heating rate is controlled within 2-3°C / min, and the temperature and pressure time is maintained for more than 90 minutes.

[0052] The buffer layer in step S7 includes an upper release film located at the upper layer, a silicone sheet located at the middle layer, and a lower release film located at the lower layer.

[0053] In step S4, the browning process is to micro-etch the copper surface of the copper-aluminum composite plate using H2O2 and H2SO4. The organic additives in the browning solution react with the copper surface to form an organic metal conversion film. The metal conversion film is embedded in the copper surface to form a grid-like conversion layer between the copper surface and the resin.

[0054] In step S2, the copper-aluminum composite plate contains 15% copper, and a copper layer of 155-165 μm is etched to form the boss. The copper layer of the copper-aluminum composite plate is etched step by step with the copper layer facing downward.

[0055] In step S2, the copper-aluminum composite plate is etched step by step with the copper layer facing downward. The specific steps are: first, etching at a line speed of 3.0 m / min to etch a copper thickness of 90 μm; second, etching at a line speed of 2.4 m / min to etch a copper thickness of 60 μm.

[0056] The LED thermal and electrical separation aluminum substrate includes L1, L2, L3 and L4 layers distributed in layers from top to bottom. The L1 and L2 layers are FR-4 substrates, and the L3 and L4 layers form a copper-aluminum composite plate. The L3 layer is a copper layer, and the L4 layer is an aluminum layer. The boss is located in the middle of the L3 layer.

[0057] In step S7, the specific steps of arranging and pressing the FR-4 substrate, the copper-aluminum composite board and the buffer layer to form a board are as follows: first, the copper-aluminum composite board is browned, and after cooling, the aluminum layer protective film needs to be torn off, and the release film of the pure adhesive surface is torn off, and then combined with the L3 layer of the copper-aluminum composite board, the board is firmly glued to fix the four corners, and the buffer layer is used instead of the copper foil to double-assemble the board.

[0058] The specific steps of applying the pure adhesive in step S4 are as follows: first, remove the pure adhesive release paper, then adhere it to the bottom surface of the FR-4 substrate in a straight direction, and pass it through a thermoforming machine once. The thermoforming machine needs to be heated to 110°C.

[0059] In step S6, the gong groove is a groove for the gong boss to fit in, and a double-edged milling cutter is used to reduce burr residue when gonging the groove.

[0060] Example 1: A manufacturing process for an LED thermal and electrical separation aluminum substrate

[0061] 1. Cutting of FR-4 substrate and copper-aluminum composite board

[0062] Use a CNC cutting machine to cut to the corresponding size. The bottom aluminum layer of the copper-aluminum composite plate is covered with a protective film. Be careful of scratches or crushing during the cutting and handling process. The damaged protective film will not provide protection, and post-process etching may cause dents in the aluminum layer.

[0063] 2. Drilling of FR-4 substrate and copper-aluminum composite board

[0064] This drilling only drilled LDI positioning holes at the four corners of the board. The copper-aluminum composite board was drilled with the copper layer facing up. After drilling, the FR-4 layer was polished normally to remove the burrs. The copper layer of the copper-aluminum composite board was covered with a PVC protective film, which needed to be removed before polishing, leaving only the protective film of the aluminum layer.

[0065] 3. Fabrication of L1 and L2 layers of FR-4 substrate

[0066] The thickness of the FR-4 substrate is 0.25mm. During the pre-processing of the optical imaging, red tape should be attached to the edge of the optical board and the board should be carried through the pre-processing. When pressing the dry film, the board should be held with both hands and finger cots should be worn to prevent wrinkling and oxidation of the board surface. Turn on the pressure switch and adjust it to 6kg / cm 2 ; Use a new knife to cut the film to prevent the dry film from breaking into pieces and falling onto the board, which will cause poor exposure and short circuits. Be careful not to damage the soft board when applying enough force. During negative film exposure, the exposure table and glass Mylar must be cleaned to prevent short circuits.

[0067] 4. Etch the L1 layer circuit and etch the L2 layer bare board

[0068] 5. L3-L4 layer boss exposure

[0069] It is made of 15% copper-aluminum composite board with a thickness of 1.6mm, of which the copper thickness is 225μm. The copper layer of 155-165μm needs to be etched to make the boss. During the pre-treatment of the outer layer, the lower grinding brush needs to be turned off, the board is ground on one side, and dry film is applied to both sides of the copper-aluminum board. The negative film is exposed. In this step, the copper layer boss pattern is made and the entire aluminum layer is exposed to protect the aluminum layer from being attacked by the liquid.

[0070] 6. Boss etching

[0071] Acid etching: This step requires etching 155-165μm on a 225μm base copper layer, with the copper layer facing downward. In the first step, etch 90μm of copper at a line speed of 3.0m / min; in the second step, etch 60μm at a line speed of 2.4m / min. The first etched piece must be sectioned with a metallographic microscope to measure the height and width of the bumps. Qualified pieces are then ready for mass production.

[0072] 7. Apply pure glue to the L2 layer

[0073] Before operation, check that the L2 layer has been etched cleanly. Ensure the entire surface is free of residual copper and contaminants. Sandblasting can be used to clean the adhesive. The adhesive must be refrigerated and allowed to thaw for two hours after shipment. First, remove the adhesive release paper. Then, laminate the adhesive to the underside of the FR-4 substrate, ensuring the correct orientation. Both layers should be run through a thermoformer heated to 110°C. This heat creates a certain degree of adhesiveness, facilitating a preliminary bond with the substrate. Further trim any excess adhesive from the edges of the board and run it through a manual laminator for further compaction.

[0074] 8. FR-4 substrate layer with glue groove

[0075] After the adhesive is bonded to the substrate, further drilling is required to align the holes with the L1 circuit pattern. Using a CCD punch, drill the holes with the adhesive facing up. After completion, the grooves are cut to create the bosses and grooving grooves. Using a double-edged milling cutter can reduce burrs, and the upper and lower clamps are compacted.

[0076] 9. Pressing

[0077] First, brown the copper-aluminum composite board. After cooling, remove the aluminum protective film (this film is not heat-resistant). Remove the release film from the pure adhesive surface and bond it to the L3 layer of the copper-aluminum composite board. Use a 10x magnification microscope to observe the fit between the boss and the groove. Then, secure the four corners of the board with high-temperature tape. Replace the copper foil with a three-in-one silicone pad (buffer layer). Double-ply the board, applying a 50% higher pressure than that of a normal FR-4 substrate. After lamination, use an X-ray target drill to drill the target holes.

[0078] 10. Grinding rubber + drilling peripheral holes

[0079] Use a three-in-one silicone pad, the amount of pure glue overflow is small, and it can be passed through the copper plating rough grinder normally; drill the outer holes of the board and locate the target holes.

[0080] 11. Solder mask, text

[0081] To make solder mask and text normally, it is necessary to pay attention to that before grinding the solder mask, the aluminum layer of the aluminum composite plate needs to be protected by blue tape, the lower grinding brush needs to be turned off before solder mask treatment, and the protective tape should be torn off after the text is baked.

[0082] 12. Immersion Gold

[0083] The entire surface of the aluminum layer is covered with film and compacted without any gaps to ensure that the aluminum layer is not damaged during the micro-etching cylinder section and only the top layer is etched with gold.

[0084] 13. Secondary drilling

[0085] Normal drilling operation requires the use of high-density pads and aluminum sheets. A drilling rig with a revolution of 160,000 or more must be used. The number of stacked plates is a maximum of 2 plates per stack. The gold surface cannot be polished after drilling.

[0086] 14. Forming and grinding the aluminum layer

[0087] V-CUT requires the use of a diamond knife, the tool speed is reduced by 30%, and the travel speed is reduced by 50%. After the V-cut, burrs remain on the board surface. The gold surface is formed with blue tape, and the aluminum layer faces downward during the gong process. After forming, the aluminum layer is polished with a single-sided brush on the copper plate grinding machine to remove burrs and oxides from the aluminum layer.

[0088] 15. Electrical test: Test according to routine requirements

[0089] After production is completed, the LED thermal and electrical separation aluminum substrate is subjected to thermal stress testing

[0090] The pressed board samples were subjected to thermal shock test at 288℃*10S*8 times to check the blistering and delamination effects of the board; the results showed that there was no blistering or delamination on both sides of the manufactured LED thermal and electrical separation aluminum substrate.

[0091] Solderability test

[0092] Place the sample in an oven at 105±5℃ for 1-2 hours to dry out moisture and other volatiles on the board surface. After baking, cool to room temperature and immerse the sample completely in rosin for 5-10 seconds. Remove the sample, place it vertically for 1 minute and absorb the rosin on the sample surface. Clamp the sample flat and let it float on the tin surface for 3-5 seconds.

[0093] After the test time is up, the sample is carefully removed from the soldering surface and kept horizontal until it solidifies, and the tinning effect is observed; the results show that the tinning effect on the gold surface is good and there is no tin sticking to the aluminum layer.

[0094] Glue overflow inspection: The results show that the glue overflow is in good condition. Figure 11 and Figure 12 shown.

[0095] Since the bottleneck of heat dissipation is the insulating layer on the aluminum substrate, a new process of thermoelectric separation can be used to process the aluminum substrate for automotive LED lights, greatly enhancing the heat dissipation capacity of LED lamps. Under the original LED base of the aluminum substrate, the copper cladding and the insulating layer are removed to expose the thermally conductive aluminum plate. However, aluminum cannot be directly soldered, so a metal layer that can be soldered needs to be plated on the exposed aluminum plate. After the aluminum substrate processing and welding is completed, the heat generated by the PN junction of the LED passes through the LED base → solder paste welding block → aluminum plate → thermal conductive silicone gasket → heat dissipation aluminum profile → and dissipates into the air. After the new lamp structure removes the insulating layer with a very small thermal conductivity coefficient, the LED heat dissipation capacity is greatly enhanced, which directly extends the LED lighting time and service life. Figure 3 As shown; this application adopts Lianzhi pure glue pressing technology, metal substrate etching and copper convex technology, pure glue CNC cutting technology, covering film protection technology, dynamic area window opening technology, metal base molding technology, etc., which solves the current technical bottleneck and is suitable for the production of new automotive LED thermoelectric separation aluminum substrates.

[0096] Key technical issues solved by this application:

[0097] The new LED thermal and electrical separation aluminum substrate is made of copper-aluminum composite material, with local etching of bosses and pure adhesive pressing. The key technical issues involved are as follows:

[0098] 1. Bubble problem in non-flowing pure glue plywood

[0099] Since the colloid fluidity of non-flowing pure glue is poor, uniform pressure buffering is required during the pressing process to achieve the effect of colloid exhaust, so bubbles are easily generated during the pressing process. From the perspective of the mechanism of non-flowing pure glue itself, the glue itself has no fluidity, and the filling area is mainly press negative pressure in a vacuum environment and high pressure contact to achieve complete adhesion. Therefore, try to use materials with excellent buffering properties as the buffer layer to increase the pressure on the filling area; such as Figure 4 shown.

[0100] Solution:

[0101] Excellent cushioning material can enhance the pressure of the filling area, so that the area can be filled fully after being compressed. Avoid the phenomenon of lack of glue. The cushioning layer uses three-in-one material, which is divided into three layers, such as Figure 5 As shown; the upper and lower layers are high-temperature release films, and the middle layer is a silicone sheet, which has excellent pressure-relieving ability and high heat resistance. It is not easy to deform after high pressure, and the heat transfer performance is also very good.

[0102] The initial temperature of pure adhesive pressing is between 110-130℃. Place the bonding board to be pressed, and the pressure applied by the press needs to be controlled at 30-40kgf / cm². Conventional flow epoxy materials require a temperature range of 80-140℃, and a heating rate of 1.5-2.5℃ / min. Lianzhi pure adhesive materials require a temperature range of 110-160℃, a heating rate of 2-3℃ / min, and the temperature and pressure time must be maintained for more than 90 minutes. Figure 6 shown.

[0103] 2. Control of depression around the convex copper: Use pure adhesive for lamination. The material properties determine the width of the glue overflow at the edge of the board. This project uses Lianzhi pure adhesive material, and the glue overflow during lamination is ≤0.2mm. If the window opening of the FR-4 substrate material and the specifications of the convex copper block of the composite layer cannot be matched accordingly, there will be problems with gap interference or boss coverage.

[0104] Solution:

[0105] Before the test, take the pure glue and stick it to the FR-4 substrate copper clad board and make a 2*3mm square groove, then add the FR-4 substrate and overlap and press it. After completion, send it to the laboratory for sectioning and measure the distance of the overflow glue. Figure 7 As shown in the figure: The actual amount of glue overflow and the engineering compensation coefficient were determined through experiments, thus solving the problem of pure glue sinking and overflowing at the junction of the convex copper and the FR-4 substrate window; finally, it was determined that the compensation data of the pure glue groove is 0.15mm larger than the single side of the convex copper.

[0106] 3. The bonding strength between pure glue and FR-4 substrate and copper layer

[0107] Lianzhi's pure adhesive has poor adhesion to FR-4 substrates, which can easily cause cracking and voids between bonding layers. This is primarily due to the fact that the bottom layer of the FR-4 substrate is etched into a bare board with a thickness of 0.25mm, and the top layer has circuit patterns. During lamination, the substrate's pressure-bearing areas are uneven, and localized areas without copper present no pressure, which can easily form voids. Pure adhesive is highly inert, and even at high temperatures, the adhesive within the adhesive lacks sufficient fluidity to fully fill gaps. Therefore, ensuring a complete bond between the adhesive and the substrate is key to resolving interlayer voids.

[0108] Solution:

[0109] After the copper-aluminum composite plate is etched with the boss, it is subjected to browning treatment. Browning is a micro-etching treatment on the copper surface using H2O2 and H2SO4. The organic additives in the browning solution react with the copper surface to form an organic metal conversion film. This film can effectively embed into the copper surface, forming a grid-like conversion layer between the copper surface and the resin. Figure 8 shown.

[0110] Reaction equation:

[0111] Cu + H2SO4+H2O2 → CuSO4+2H2O

[0112] Cu + nA → Cu(A)n → Brown Coating

[0113] The LED thermal and electrical separation aluminum substrate is shown in Figure 9. The LED thermal and electrical separation aluminum substrate includes L1, L2, L3 and L4 layers distributed in layers from top to bottom. The L1 and L2 layers are FR-4 substrates, and the L3 and L4 layers form a copper-aluminum composite plate. The L3 layer is a copper layer, and the L4 layer is an aluminum layer. The boss is located in the middle of the L3 layer.

[0114] Among them, L3 is a copper layer with etched bosses, and L4 is a smooth aluminum layer with no vias in the board. The bosses fit into the grooves of the FR-4 substrate.

[0115] The design focus of the present invention is to solve the problem of bubbles in the non-flowing pure glue pressing plate by adopting the production process of the LED thermoelectric separation aluminum substrate provided by this application, realize the control of the depression around the convex copper, and ensure the bonding strength between the pure glue and the FR-4 substrate and the copper layer; the use of the produced LED thermoelectric separation aluminum substrate greatly enhances the heat dissipation capacity of the LED, directly extending the LED lighting time and service life; it adopts Lianzhi pure glue pressing technology, metal substrate etching convex copper technology, pure glue CNC cutting technology, covering film protection technology, dynamic area window opening technology, metal base molding technology, etc., which solves the current technical bottleneck and is suitable for the production of new automotive LED thermoelectric separation aluminum substrates.

[0116] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A process for manufacturing an LED thermal and electrical separation aluminum substrate, characterized by: The steps include: S1. Cut FR-4 substrate, copper-aluminum composite board and pure glue respectively; S2, first make a copper-aluminum composite plate, apply dry film etching, and form a local boss; Make GTL layer circuit on S3 and FR-4 substrate, and etch with dry film negative; S4, FR-4 substrate is browned and then coated with pure glue and compacted by laminator: copper-aluminum composite board is browned with browning liquid after the boss is etched; S5. Drill corresponding target holes according to the target designed for the FR-4 substrate; S6. Window processing is performed on the FR-4 substrate corresponding to the boss area, and the compensation value of the window area is reasonably compensated: pure glue is applied to the FR-4 substrate and grooves are formed, and then the FR-4 bare board is superimposed and pressed. The distance of the overflow glue is measured by slicing to determine the actual overflow glue amount and the engineering compensation coefficient. The compensation data of the pure glue groove is 0.1-0.2mm larger than the single side of the boss. S7. Lay out and press the FR-4 substrate, copper-aluminum composite board and buffer layer to form a board: the initial temperature of pure glue pressing is 110-130℃, and press the combined board to be pressed; S8, drilling the pressed plates; S9, do outer layer solder mask and surface treatment; S10, electrical testing and forming; The buffer layer in step S7 includes an upper release film located on the upper layer, a silicone sheet located on the middle layer, and a lower release film located on the lower layer; The LED thermal and electrical separation aluminum substrate includes an L1 layer, an L2 layer, an L3 layer, and an L4 layer distributed in layers from top to bottom. The L1 layer and the L2 layer are FR-4 substrates. The L3 layer and the L4 layer form a copper-aluminum composite plate. The L3 layer is a copper layer, and the L4 layer is an aluminum layer. The boss is located in the middle of the L3 layer. In step S7, the specific steps of arranging and pressing the FR-4 substrate, the copper-aluminum composite board and the buffer layer to form a board are as follows: first, the copper-aluminum composite board is browned, and after cooling, the aluminum layer protective film needs to be torn off, and the release film of the pure adhesive surface is torn off, and then combined with the L3 layer of the copper-aluminum composite board, the board is firmly glued to fix the four corners, and the buffer layer is used instead of the copper foil to double-assemble the board.

2. The process for manufacturing the LED thermal and electrical separation aluminum substrate according to claim 1, characterized in that: In step S7, a press is used for pressing, and the pressure applied by the press is controlled to be 30-40 kgf / cm², the pressing temperature of the pure glue is 110-160°C, the heating rate is controlled within 2-3°C / min, and the temperature and pressure time is maintained for more than 90 minutes.

3. The process for manufacturing the LED thermal and electrical separation aluminum substrate according to claim 1, characterized in that: In step S4, the browning process is to micro-etch the copper surface of the copper-aluminum composite plate using H2O2 and H2SO4. The organic additives in the browning solution react with the copper surface to form an organic metal conversion film. The metal conversion film is embedded in the copper surface to form a grid-like conversion layer between the copper surface and the resin.

4. The process for manufacturing the LED thermal and electrical separation aluminum substrate according to claim 1, characterized in that: In step S2, the copper-aluminum composite plate is a copper-aluminum composite plate containing 15% copper, and a copper layer of 155-165 μm is etched to make the boss, and the etching is carried out step by step with the copper layer of the copper-aluminum composite plate facing downward.

5. The process for manufacturing the LED thermal and electrical separation aluminum substrate according to claim 4, characterized in that: The specific steps of etching the copper-aluminum composite plate in step S2 with the copper layer facing downward are as follows: first, etching at a line speed of 3.0 m / min to etch the copper to a thickness of 90 μm; Second: Etching line speed 2.4m / min etching 60μm.

6. The process for manufacturing the LED thermal and electrical separation aluminum substrate according to claim 1, characterized in that: The specific steps of applying the pure adhesive in step S4 are as follows: first, remove the pure adhesive release paper, then adhere it to the bottom surface of the FR-4 substrate in a straight direction, and pass it through a thermoforming machine once. The thermoforming machine needs to be heated to 110°C.

7. The process for manufacturing the LED thermal and electrical separation aluminum substrate according to claim 1, characterized in that: In step S6, the gong groove is a groove for the gong boss to fit in, and a double-edged milling cutter is used to reduce burr residue when gonging the groove.

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