Novel high-efficiency semiconductor lead frame production process

Abstract

The invention discloses a high-efficiency new production process of a semiconductor lead frame, which comprises the following steps of: 1, providing a substrate with a width required for producing two or more material strips, performing one-time stamping on the substrate to form two or more connected material strips, and setting the two or more connected material strips as one group; step 2, carrying out electroplating treatment on the material belt; thirdly, the two sets of material belts are subjected to mold forming; step 4, bending process; stamping is carried out through a stamping machine, two rows or multiple rows of support material belts, namely two connected material belts, can be stamped in one base plate, then the base plate is electroplated, then the two sets of material belts can be subjected to compression molding, and the width of each set of material belt is equal to the width of the two rows or multiple rows of supports; therefore, the number of rows of supports can be achieved through one-time injection molding of the injection molding machine, and the productivity is improved by one time or several times.

Description

Technical Field

[0001] The invention belongs to the technical field of LED bracket production, and specifically relates to a new production process for a highly efficient semiconductor lead frame. Background Art

[0002] An LED bracket is a core structural component for LED packaging, mainly formed by precision stamping or etching of conductive metal. The LED bracket can be used for mechanically supporting LED lamp beads and can also be used to improve the luminous efficiency of LEDs.

[0003] The width of the raw material of the traditional existing LED bracket is the width of the raw material required for producing one strip of tape. Only one strip of metal tape can be produced in one stamping process. When the metal tape is injection-molded after multiple stampings, only two strips of tape can be injection-molded simultaneously, resulting in low production efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a new production process for a highly efficient semiconductor lead frame to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A new production process for a highly efficient semiconductor lead frame, comprising: Step 1: Provide a substrate with a width required for producing two or more strips of tape, and perform one stamping on the substrate to form two or more connected strips of tape. Let these two or more connected strips of tape be one group; Step 2: Perform electroplating treatment on the strip of tape; Step 3: Repeat Step 1 and Step 2 to form two groups of electroplated strips of tape. Two or more strips of tape in each group are connected to each other. Using a high-precision injection molding machine, perform mold forming on the two groups of strips of tape simultaneously to form a bracket strip of tape; Step 4: Bending process: Perform precise cutting and separation on the bracket strip of tape to obtain a number of individual brackets.

[0006] In a further technical solution, in Step 2, the electroplating treatment method includes: A1: Put the strip of tape into the electrolyte solution, clean the oil stains and dirt on the surface of the strip of tape, perform three-stage water washing on the strip of tape, perform pickling activation on the strip of tape, and then perform three-stage water washing again; A2: Deposit a layer of copper on the surface of the strip of tape. The thickness range of the copper plating layer is 0.125 μm - 0.75 μm, and perform three-stage water washing on the strip of tape; A3: Deposit a layer of acid copper on the surface of the strip of tape. The thickness range of the acid copper plating layer is 1 μm - 3.75 μm, and perform three-stage water washing on the strip of tape; A4: Deposit a layer of nickel on the strip, with the thickness of the nickel plating layer ranging from 0.125 μm to 0.875 μm, and perform three-stage water washing on the strip; deposit a layer of silver on the strip, with the thickness of the first silver plating layer ranging from 0.025 μm to 0.25 μm, and perform three-stage water washing on the strip. A5: Set the functional area in the strip as the mold window opening position, and shield the non-functional area of the strip using an electroplating mold; deposit a layer of silver on the functional area of the strip, with the thickness of the second silver plating layer ranging from 0.125 μm to 5 μm, and perform three-stage water washing on the strip.

[0007] A further technical solution also includes A6: Silver stripping treatment, strip the first silver plating layer on the non-functional area of the product, and perform three-stage water washing on the strip. A7: Immerse the product in a protective agent, take out the product, perform three-stage water washing, and then dry and collect the material.

[0008] A further technical solution, in step one, the substrate uses a C1940 copper alloy strip with a thickness of 0.15 - 0.3 mm, the tensile strength of the substrate ≥ 600 MPa, and the conductivity of the substrate ≥ 65%.

[0009] A further technical solution, in step one, two or more of the strips are connected by connecting ribs, and the connecting ribs are provided with stress relief holes evenly distributed, and the diameter range of the aperture of the stress relief holes is 0.1 - 0.3 mm.

[0010] A further technical solution, in step three, the mold temperature of the high-precision injection molding machine is controlled at 120°C - 135°C, the injection pressure of the high-precision injection molding machine is 85 Pa - 110 MPa, and the holding pressure time is 6 s - 8 s.

[0011] Advantages of the present invention: The present invention provides that the operator uses a substrate with the width of two or more strips for stamping, and performs stamping through a stamping machine, and can stamp out two rows or more rows of strip-shaped brackets in one substrate, that is, two or more connected strips. Then, electroplate the substrate, that is, electroplate metal on the pin part to improve the electrical conductivity of the bracket. After that, two groups of strips can be molded by pressing. The width of each group of strips is the width of two rows or more rows of brackets; furthermore, the injection molding machine can complete the quantity of multiple rows of brackets in one injection, increasing the production capacity by 1 time or several times. Through precise cutting and separation of the bracket strip in the bending process, after separation, it is necessary to comprehensively detect the bent LEDs to ensure the elimination of unqualified brackets; in order to further increase the elimination of unqualified brackets, in this embodiment, an automatic detection device AOI is used to realize the second detection of the brackets, improving the detection efficiency.

[0012] Other features and advantages of the present invention will be described in detail in the following specific implementation part. Description of the Drawings

[0013] Figure 1 : Flow chart of the present invention.

[0014] Figure 2 : Process diagram of the background technology of the present invention.

[0015] Figure 3 : Process diagram of the present invention.

[0016] Figure 4 : Comparison diagram of the background technology of the present invention and the raw material stamping of the present application.

[0017] Figure 5 : Schematic diagram of the injection molding method of the background technology of the present invention.

[0018] Figure 6 : Schematic diagram of the injection molding method of the present invention.

[0019] Figure 7 : Comparison diagram of the background technology of the present invention and the bending method of the present application. Specific Implementation

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0021] Please refer to Figures 1-7 ; LED lamp is a solid-state lighting device based on the electroluminescence effect of semiconductor PN junction. It realizes efficient photoelectric conversion by the recombination of carriers to release light energy, and has advantages such as low energy consumption, long life, and fast response. It is widely used in multiple fields such as indoor and outdoor lighting, backlighting of electronic devices, automotive lamps, display screens, and medical sterilization. The core components of an LED lamp include components such as an LED chip, encapsulation colloid, lead frame, and LED bracket. Among them, the LED bracket, as a key load-bearing structure, is mainly formed by stamping a metal substrate (such as copper alloy) into conductive pins and a reflector cup (bowl cup structure). Its surface forms a multi-layer silver reflective layer through gradient electroplating. During the encapsulation process, it not only provides mechanical support and electrical connection for the chip, but also realizes the directional enhancement of light through the precisely formed reflector cup structure. At the same time, the metal matrix itself also undertakes the function of a heat dissipation channel to ensure the stable operation of the device in a high-temperature environment.

[0022] In the existing manufacturing process of LED brackets, the width of the substrate usually selected is the same as that of a row of LED brackets. The production uses a single strip of tape, that is, the conventional 75mm width. Each stamping process can only form a single strip of tape, forcing the production line to have to accumulate the number of strips of tape through repeated stamping cycles; in the injection molding process, each molding cycle of the high-value injection molding equipment can still only process two strips of tape simultaneously, which is seriously out of sync with the high-speed production capacity of 800 times per minute of the stamping machine, seriously reducing the production efficiency.

[0023] The present invention discloses a new production process for high-efficiency semiconductor lead frames, including: Step 1, provide a substrate 10 with a width required for producing two or more strips of tape, perform a single stamping on the substrate 10 to form two or more connected strips of tape, and set the two or more connected strips of tape as one group; Step 2, perform electroplating 20 treatment on the strip of tape; Step 3, repeat Step 1 and Step 2 to form two groups of electroplated strips of tape. Two or more strips of tape in each group are connected to each other. Use a high-precision injection molding machine to simultaneously perform mold forming 30 on the two groups of strips of tape to form a bracket strip of tape; Step 4: Bending process 40: Perform precise cutting and separation on the bracket strip of tape to obtain a number of individual brackets.

[0024] Step 5, conduct a comprehensive quality inspection on the bent brackets, including appearance inspection, dimension measurement, product airtightness test, etc.

[0025] Step 6, automation and technological innovation: Introduce an automated detection device AOI to perform a re-inspection on the inspected LED brackets.

[0026] Specifically, in this embodiment, the number of a set of strip materials is set to two strip materials. The operator uses a substrate with the width of two strip materials for stamping. Through a stamping machine, two rows of strip materials of brackets can be stamped out in one substrate, that is, two connected strip materials. Then, the substrate is electroplated, that is, metal is electroplated on the pin part of the functional area to improve the electrical conductivity of the LED bracket. After that, two sets of strip materials can be molded by die pressing. The width of each set of strip materials is the width of two rows of brackets. In addition, the mold temperature of the high-precision injection molding machine is controlled at 120°C - 135°C, the injection pressure of the high-precision injection molding machine is 85 Pa - 110 MPa, and the holding pressure time is 6 s - 8 s. In this embodiment, the mold temperature of the high-precision injection molding machine is preferably 130°C, the injection pressure of the high-precision injection molding machine is preferably 100 MPa, and the holding pressure time is preferably 7 s, so as to improve the accuracy and safety performance of die pressing; furthermore, the injection molding machine can complete the quantity of 4 rows of brackets in one injection molding, doubling the production capacity. Through precise cutting and separation of the LED bracket strip materials in the bending process, the bending process cuts and separates the two connected LED bowl cup strip materials formed by injection molding at the same time, and then completes the cutting of two strip materials, doubling the production capacity of bending; after separation, it is necessary to conduct a comprehensive inspection on the bent ones to ensure the elimination of unqualified LED brackets; in order to further increase the elimination of unqualified brackets, in this embodiment, an automatic detection device AOI is used to achieve the second detection of the LED brackets, improving the detection efficiency.

[0027] In this embodiment, in step two, the treatment method of electroplating includes: A1: Put the strip material into the electrolyte solution, clean the oil stains and dirt on the surface of the strip material, conduct three-stage water washing on the strip material, conduct pickling activation on the strip material, and then conduct three-stage water washing again; A2: Coat a layer of copper on the surface of the strip material. The thickness range of the copper coating is 0.125 μm - 0.75 μm, and conduct three-stage water washing on the strip material; A3: Coat a layer of acid copper on the surface of the strip material. The thickness range of the acid copper coating is 1 μm - 3.75 μm, and conduct three-stage water washing on the strip material; A4: Coat a layer of nickel on the surface of the strip material. The thickness range of the nickel coating is 0.125 μm - 0.875 μm, and conduct three-stage water washing on the strip material; Coat a layer of silver on the surface of the strip material. The thickness range of the first silver coating is 0.025 μm - 0.25 μm, and conduct three-stage water washing on the strip material; A5: Set the functional area in the strip material as the position where the mold is opened, and shield the non-functional area with an electroplating mold; Coat a layer of silver on the functional area on the surface of the strip material. The thickness range of the second silver coating is 0.125 μm - 5 μm, and conduct three-stage water washing on the strip material; A6: Silver stripping treatment, strip the first silver coating on the non-functional area of the product, and conduct three-stage water washing on the strip material; A7: Let the product soak in the protective agent, take out the product, conduct three-level water system, and then dry and collect the material.

[0028] Specifically, in the present embodiment, one group of strips, i.e., two or more connected strips, are electroplated at the same time, which can improve product efficiency and reduce costs. The electroplating process is followed by electroplating discharge, electrolytic degreasing, i.e., cleaning the oil stains and dirt on the surface of the strips, followed by three-stage water washing, followed by acid pickling activation, i.e., polishing, to corrode the oxide layer or impurities on the surface of the strips, followed by three-stage water washing, followed by pre-plating alkaline copper, i.e., plating a layer of copper to preheat for subsequent electroplating to ensure the bonding of the plating layer, with a thickness of 0.125μm-0.75μm, preferably 0.5μm, followed by three-stage water washing, followed by acid copper plating, the purpose of acid copper plating is to fill the lines and pits on the surface of the strips to make the surface of the strips smooth and flat, with a thickness of 1μm-3.75μm, preferably 2μm, followed by three-stage water washing, followed by nickel plating, with a thickness of The thickness is 0.125-0.875μm, preferably 0.5μm, and then three-level water washing is carried out for pre-silvering. The material strip is immersed in silver plating as a whole, so that a layer of silver is plated on the surface of the product, that is, the first silver plating layer, in preparation for the subsequent silver plating to ensure the bonding of the plating layer, the thickness is 0.025μm-0.25μm, preferably 0.2μm, and then three-level water washing is carried out, and then the silver plating is carried out, that is, the second silver plating layer, that is, after the electroplating mold, the functional area can be silver-plated, and the non-functional area can not be silver-plated, the thickness is 0.125μm-5μm, preferably 0.25μm, and then three-level water washing is carried out, and then the silver is removed, that is, the pre-silvered layer on the non-functional area of ​​the product is removed, and then three-level water washing is carried out; then the product is immersed in a certain concentration of protective agent, the purpose is to enhance the oxidation resistance of the plating layer, and then three-level water washing is carried out and dried to collect the material.

[0029] In this embodiment, in step 1, the substrate is made of C1940 copper alloy strip with a thickness of 0.15mm-0.3mm. In this embodiment, the thickness is preferably 0.25mm. The 0.25mm thick substrate can increase the mechanical strength by 12% compared with the 0.15mm thick substrate, effectively avoiding micro cracks generated in the strip during high-speed stamping, and reducing the warping deformation in the electroplating process; compared with the 0.3mm specification, the weight of a single strip is reduced, so that the uniformity of thermal stress distribution during injection molding is improved, and the material cost is saved, achieving the optimal balance between structural strength and process adaptability. In addition, it is necessary to ensure that the tensile strength of the substrate is ≥600MPa and the conductivity of the substrate is ≥65%.

[0030] In this embodiment, in step 1, two or more material strips are connected by connecting ribs, and the connecting ribs are provided with stress release holes distributed at equal intervals, and the diameter range of the stress release holes is 0.15-0.3 mm; More specifically, in this embodiment, the width of the connecting rib is 2.0 mm. Compared with the 1.6 mm specification, the 2.0 mm width can improve the transverse tensile strength and effectively prevent the rib fracture accident during high-speed stamping. Compared with the 2.4 mm design, it reduces material consumption and decreases the shearing force in the strip separation process. With the connecting rib as the support and in combination with the special arrangement of 0.2 mm stress relief holes, the local stress concentration coefficient during the electroplating process can be decreased.

[0031] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0032] In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims

1. A new high-efficiency semiconductor lead frame production process, characterized in that: include: Step 1, providing a substrate of a required width for producing two or more material strips, and punching the substrate once to form two or more connected material strips, wherein the two or more connected material strips are referred to as one group; Step 2, electroplating the material strip; Step 3, repeating steps 1 and 2 to form two groups of electroplated strips, wherein two or more strips in each group are connected to each other, and a high-precision injection molding machine is used to simultaneously mold the two groups of strips to form a bracket strip; Step 4: Bending process: Precisely cut and separate the stent strip to obtain a number of individual stents.

2. A new high-efficiency semiconductor lead frame production process according to claim 1, characterized in that: In the step 2, the electroplating treatment method includes: A1: Put the material strip into the electrolyte, clean the oil stains and dirt on the surface of the material strip, wash the material strip with three levels of water, and then acid wash and activate the material strip and then wash it with three levels of water again; A2: A layer of copper is plated on the surface of the material strip, the thickness of the copper plating layer ranges from 0.125μm to 0.75μm, and the material strip is washed three times; A3: A layer of acid copper is plated on the surface of the material strip, the thickness of the acid copper plating layer ranges from 1μm to 3.75μm, and the material strip is washed three times; A4: Plate a layer of nickel on the surface of the material strip, the thickness of the nickel plating layer ranges from 0.125μm to 0.875μm, and wash the material strip three times with water; Plate a layer of silver on the surface of the material strip, the thickness of the silver plating layer one ranges from 0.025μm to 0.25μm, and wash the material strip three times with water; A5: The functional area in the material strip is set as the mold window position, and the non-functional area is masked by electroplating mold; a layer of silver is plated on the functional area on the surface of the material strip, and the thickness of the second silver plating layer ranges from 0.125μm to 5μm, and the material strip is washed with three levels of water.

3. A new high-efficiency semiconductor lead frame production process according to claim 2, characterized in that: Also includes A6: Desilvering treatment, de-plating the silver layer on the non-functional area of ​​the product, and performing three-electrode water washing on the material strip; A7: Let the product soak in the protective agent, take out the product, conduct three-level water system, and then dry and collect the material.

4. The new high-efficiency semiconductor lead frame production process according to claim 1, characterized in that: In the step 1, the substrate is made of C1940 copper alloy strip with a thickness of 0.15-0.3 mm, a tensile strength of the substrate of ≥600 MPa, and a conductivity of the substrate of ≥65%.

5. The new high-efficiency semiconductor lead frame production process according to claim 1, characterized in that: In the step 1, two or more of the material strips are connected by connecting ribs, and the connecting ribs are provided with stress release holes distributed at equal intervals, and the diameter range of the stress release holes is 0.1-0.3 mm.

6. The new high-efficiency semiconductor lead frame production process according to claim 1, characterized in that: In the step three, the mold temperature of the high-precision injection molding machine is controlled at 120°C-135°C, the injection pressure of the high-precision injection molding machine is 85Pa-110MPa, and the holding time is 6S-8S.

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