Device for semiconductor circuit

Abstract

The present invention discloses a device for semiconductor circuits, including a frame positioning bar and reinforcing ribs, wherein a long side of the frame positioning bar vertically extends outward with a plurality of pins, each pin is arranged at intervals, and the tail end of the pin has a packaging section for fixing in a plastic package, the packaging section includes a sinking section bent and arranged below the plane where the frame positioning bar is located, and the end of the sinking section is warped upward; the reinforcing rib spans and connects each pin, and the reinforcing rib is located between the packaging section and the frame positioning bar. According to the technical solution of the present invention, during the MIPS injection molding process, the substrate will be placed in the mold cavity in an inclined state due to the upward warping of the ends of the pins, thus reducing the resistance of the plastic packaging material in the mold cavity, balancing the filling time of the plastic packaging material on the upper and lower surfaces of the substrate, ensuring that the air in the mold cavity can be discharged from the gap between the pin and the mold, avoiding the occurrence of pore defects in the plastic packaging shell, and ensuring the product quality of MIPS.

Description

Technical Field

[0001] The present invention relates to the field of power semiconductors, and in particular to a device used in semiconductor circuits. Background Art

[0002] Semiconductor circuits are power-driven products that combine power electronics and integrated circuit technology. In the manufacturing process, transfer molds are used. The substrate with all components (including chips and resistors and capacitors) and pins assembled is placed in the mold cavity, and the product's plastic package body shell is finally formed through injection molding and high-temperature curing.

[0003] The specific injection molding process is as follows: the plastic encapsulation material is injected into the mold cavity from the injection port at one end of the mold cavity, the plastic encapsulation material flows around from the injection port, and flows forward from the front (upper surface) and back (lower surface) of the substrate respectively, and finally reaches the other end of the mold cavity at the same time to form a bonding line, and the air in the mold cavity overflows through the gap between the upper mold, the lower mold and the pins, and finally the plastic encapsulation material fills the entire mold cavity and solidifies into shape. Since there are components on the front of the substrate, which is different from the structure on the back of the substrate, during the injection molding process, the flow rate of the plastic encapsulation material on the front and back of the substrate is different, and the time to be filled with the plastic encapsulation material is different. The plastic encapsulation material on the front and back of the substrate is very likely to not converge at the pins, but form a bonding line at a certain position inside the substrate, causing the air to be unable to be removed, thereby forming a pore defect. Summary of the invention

[0004] The main purpose of the present invention is to provide a device for semiconductor circuits, aiming to solve the problem of pore defects in the injection molding process of semiconductor circuit production.

[0005] To achieve the above object, the device for semiconductor circuit proposed by the present invention comprises:

[0006] A frame positioning strip, wherein a plurality of pins are vertically extended outward from one long side of the frame positioning strip, each of the pins is arranged at intervals, and the tail end of the pin has a packaging section for fixing in a plastic package body, and the packaging section includes a sinking section bent and arranged below the plane where the frame positioning strip is located, and the end of the sinking section is warped upward;

[0007] A reinforcing rib spans across and connects each of the pins, and the reinforcing rib is located between the packaging section and the frame positioning bar.

[0008] Preferably, the downward bending angle of the sinking section ranges from 30° to 50°, and the warping angle of the end of the sinking section ranges from 3° to 5°.

[0009] Preferably, the width of the pin is 200 to 800 μm, and the distance between the center lines of two adjacent pins is one of 2.54 mm, 1.27 mm, 1.78 mm, 1 mm, 0.8 mm, 0.65 mm, 0.5 mm, and 0.4 mm.

[0010] Preferably, the pins are of equal length.

[0011] Preferably, the pins are arranged at even intervals, and packaging sections of some of the pins are removed.

[0012] Preferably, the upper surface of the encapsulation section has a groove arranged adjacent to the sinking section.

[0013] Preferably, there are a plurality of grooves, and the plurality of grooves are distributed at intervals along the extension direction of the pin.

[0014] Preferably, the groove is a V-shaped groove or a U-shaped groove extending along the length direction of the frame positioning strip.

[0015] Preferably, the reinforcing rib is parallel to the frame positioning bar, and the reinforcing rib is arranged adjacent to the packaging section.

[0016] Preferably, the frame positioning strip is provided with a plurality of positioning holes evenly spaced along its length direction, and the distances between the two end portions of the frame positioning strip and the adjacent pins are equal and greater than 0.

[0017] According to the technical solution of the semiconductor circuit of the present invention, during the injection molding process of the production and manufacture of MIPS, since the warped ends of each pin are welded on the substrate, the substrate will be placed in the mold cavity in an inclined state due to the upward warping of the ends of the pins, and the end of the substrate close to the injection molding port is warped upward, thus reducing the resistance of the plastic encapsulation material in the mold cavity, balancing the filling time of the plastic encapsulation material on the upper and lower surfaces of the substrate, allowing the plastic encapsulation material on the upper and lower surfaces of the substrate to converge at the pins to form a bonding line, ensuring that the air in the mold cavity can be discharged from the gap between the pins and the mold, avoiding the occurrence of pore defects in the plastic encapsulation shell, and ensuring the product quality of MIPS. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of an embodiment of a device for a semiconductor circuit according to the present invention;

[0019] Figure 2 for Figure 1 A left side view of the device for semiconductor circuits shown;

[0020] Figure 3 for Figure 1 A partial schematic diagram of a left side view of the device for semiconductor circuit shown;

[0021] Figure 4 for Figure 3 A magnified schematic diagram of the middle C position;

[0022] Figure 5 The figure is a schematic diagram showing the relative position of the device for semiconductor circuits of the present invention to the substrate during product injection molding. DETAILED DESCRIPTION

[0023] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but are not to be construed as limiting the present invention. All other embodiments obtained by ordinary technicians in the field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0024] The semiconductor circuit mentioned in the present invention is a circuit module that integrates power switching devices and high-voltage drive circuits, and is sealed and packaged on the outside. It is widely used in the field of power electronics, such as frequency converters for driving motors, various inverter voltages, variable frequency speed regulation, metallurgical machinery, electric traction, variable frequency home appliances and other fields. The semiconductor circuit here has many other names, such as Modular Intelligent Power System (MIPS), Intelligent Power Module (IPM), or hybrid integrated circuits, power semiconductor modules, power modules and other names. In the following embodiments of the present invention, they are collectively referred to as Modular Intelligent Power System (MIPS).

[0025] The embodiment of the present invention provides a device for MIPS, which is a lead frame of MIPS and can be commonly used for various types of MIPS.

[0026] Reference Figure 1 The device for MIPS in this embodiment includes a frame positioning bar 10 and a reinforcing rib 30 .

[0027] Among them, a long side of the frame positioning strip 10 vertically extends outward with a plurality of pins 20, each pin 20 is arranged at intervals, and the tail end of the pin 20 has a packaging segment 21 for fixing in the plastic package. When the MIPS is manufactured, the end of the packaging segment 21 is welded to the pad of the substrate (a heat dissipation substrate with a circuit wiring layer). After the plastic package shell is formed by injection molding, the packaging segment 21 is plastic-sealed and fixed in the plastic package. Specifically, in conjunction with reference to Figure 2 and Figure 3The packaging section 21 includes a sinking section A bent below the plane where the frame positioning strip 10 is located, and an end B of the sinking section A is bent upward (refer to Figure 3 ). During the manufacturing process of MIPS, the warped portion (i.e., end B) of the sinking section A of each pin 20 is respectively welded and fixed to the corresponding pad on the substrate. The length of the warped portion is set according to the size of the pad, and is usually set to about one-third of the length of the pad, for example, (0.5mm to 1mm). The bent sinking section A makes it more stable and convenient when welding the pin 20, and the welding effect is better; the size of the sinking section A is determined according to the outer size of the package body.

[0028] It should be noted that in the MIPS device of this embodiment, the sinking section A and the warped portion are formed by bending through processing, and the bending parts thereof are all arc-surface structures with smooth transitions, without sharp corners, thereby improving the stress concentration problem.

[0029] Among them, the reinforcing rib 30 spans across and connects each pin 20, and the reinforcing rib 30 is located between the packaging section 21 and the frame positioning strip 10. The reinforcing rib 30 can be integrated with the pin 20 and formed by a stamping process or an etching process. Since the pin 20 is relatively slender and easy to deform, the reinforcing rib 30 is added to span and connect each pin 20, so that each pin 20 forms a whole, and the strength is improved, so that it is more firm and not easy to deform. If the size of the reinforcing rib 30 is too small, it will increase the difficulty of processing and the cost is high. If the size of the reinforcing rib 30 is too large, it will be difficult to cut it later. Therefore, the width of the reinforcing rib 30 is usually 0.5 to 2 mm.

[0030] Combined with reference Figure 5 The present embodiment is used for the device 100 of MIPS. During the injection molding process of manufacturing MIPS, since the warped ends of each pin 20 are welded to the substrate 200, the substrate 200 is placed in the mold cavity in an inclined state due to the upward warping of the ends of the pins 20. The end of the substrate 200 close to the injection port is warped upward, thereby reducing the resistance of the molding material (such as resin) in the mold cavity, balancing the filling time of the molding material on the upper and lower surfaces of the substrate 200, allowing the molding material on the upper and lower surfaces of the substrate 200 to converge at the pin 20 to form a bonding line, ensuring that the air in the mold cavity can be discharged from the gap between the pin 20 and the mold, avoiding the occurrence of pore defects in the molding shell, and ensuring the product quality of MIPS.

[0031] Of course, for the MIPS using the lead frame of the MIPS of the present embodiment, after the mold cavity is filled with the molding material by injection molding, before the molding material is cooled and formed, the substrate 200 can be pressed down to a horizontal state by a ejector pin, and the warped end where the pin 20 is welded to the substrate 200 will follow the substrate 200 to become basically horizontal. In this way, the substrate 200 in the molding shell of the final molded product is in a horizontal state.

[0032] Further, based on the analysis of the injection molding of various MIPS products, when the warping angle of the end of the sinking section A is between 3° and 5°, the plastic encapsulation materials on the upper and lower surfaces of the substrate 200 are basically combined at the pin 20, ensuring that all the air in the mold cavity is exhausted, effectively preventing the generation of air holes; therefore, the warping angle range of the end of the sinking section A in this embodiment is preferably 3° to 5°. Of course, in other embodiments, the warping angle range of the end of the sinking section A can be larger.

[0033] The downward bending angle J of the sinking section A depends on the required sinking depth. The deeper the required sinking depth, the larger the downward bending angle J. The shallower the required sinking depth, the smaller the downward bending angle J. In this embodiment, the downward bending angle range of the sinking section A is preferably 30° to 50°.

[0034] In this embodiment, the width of the pin 20 ranges from 200 to 800 μm, and the thickness of the pin 20 ranges from 200 to 600 μm to meet the current carrying capacity and the strength of the pin 20 itself. The distance between the center lines of two adjacent pins 20 is one of 2.54 mm, 1.27 mm, 1.78 mm, 1 mm, 0.8 mm, 0.65 mm, 0.5 mm, and 0.4 mm. The distance between the center lines of two adjacent pins 20 is selected according to different working circuits to meet the creepage distance and electrical clearance. Specifically, when the width of the pin 20 is larger, the distance between the center lines of the two adjacent pins 20 corresponds to the larger value of the above-listed distances; for example, when the width of the pin 20 is 800 μm, the distance between the center lines of the two adjacent pins 20 is 2.54 mm, and when the width of the pin 20 is 200 μm, the distance between the center lines of the two adjacent pins 20 is 0.4 mm. Since the pin 20 , the frame positioning strip 10 and the reinforcing rib 30 are usually formed in one piece, the thickness range of the frame positioning strip 10 and the reinforcing rib 30 is consistent with the thickness range of the pin 20 .

[0035] Since the pads on the substrate 200 are usually distributed at positions equidistant from the edge of the substrate 200, the lead frame of this embodiment uses the same length for each lead 20. Of course, in other embodiments, the lengths of each lead 20 may also be set to be unequal according to the different distribution of the pads on the substrate 200.

[0036] Further, refer to Figure 1 In this embodiment, the pins 20 are arranged at even intervals, and the encapsulation sections 21 of some pins 20 are removed. The pins 20 without the encapsulation sections 21 form dummy pins on the lead frame that are not welded to the substrate 200. Since the pins 20 of the lead frame of this embodiment are arranged at even intervals, when the pin 20 scheme of the MIPS product is changed, the position of the fixed lead frame in the encapsulation mold does not need to be changed. It is only necessary to adjust the position of the tool for cutting off the encapsulation section 21 at the lead frame processing station according to the pin 20 scheme of MIPS to cut off the lead frame that meets the pin 20 scheme of MIPS, so that the lead frame that meets the pin 20 scheme of MIPS is cut, so that the versatility is better. In addition, with this lead frame solution, after the MIPS product is packaged, the end of the pin 20 of the package segment 21 is removed and located outside the plastic package body. After the individual pins 20 are cut apart, the pin 20 of the package segment 21 is completely removed from the product without any remaining pin in the package body, which effectively solves the problem of residual empty pins 20 causing signal interference to other pins 20. Furthermore, the end of the dummy pin is very close to the plastic package body, which can prevent the plastic package material from overflowing during injection molding.

[0037] Further, refer to Figure 4 In this embodiment, a groove 211 is provided on the upper surface of the encapsulation section 21 adjacent to the sinking section A. The groove 211 effectively increases the bonding force between the encapsulation section 21 of the pin 20 and the package body, making the pin 20 and the package body more firmly fixed. To ensure that the bonding force between the encapsulation section 21 of the pin 20 and the package body is large enough, a plurality of grooves 211 are used, and the plurality of grooves 211 are spaced apart along the extension direction of the pin 20.

[0038] Furthermore, in this embodiment, the groove 211 is a V-shaped groove extending along the length direction of the frame positioning strip 10. Taking into account the strength of the pin 20 and the difficulty of processing, the notch width of the V-shaped groove in this embodiment is 0.2 to 1 mm, the center distance between adjacent V-shaped grooves is 0.5 to 2 mm, and the bottom angle of the V-shaped groove is 45° to 90°. Of course, in other embodiments, the groove 211 can also be a U-shaped groove, a trapezoidal groove, or other shapes that can enhance the bonding force.

[0039] Further, refer to Figure 1 In this embodiment, the reinforcing rib 30 is parallel to the frame positioning strip 10, so that the strength of each pin 20 is uniform, and the subsequent processing of cutting the reinforcing rib 30 is more convenient. In addition, the reinforcing rib 30 is arranged adjacent to the packaging section 21, so that when the MIPS is injected, the plastic sealing material in the mold can be blocked from overflowing, thereby ensuring the plastic sealing effect.

[0040] Further, refer to Figure 1In the lead frame of this embodiment, a plurality of positioning holes 11 are evenly spaced along the length of the frame positioning strip 10. The positioning holes 11 are preferably circular holes, with the center of the middle positioning hole 11 being at the center of the frame positioning strip 10, and the positioning holes 11 on the left and right sides being symmetrically distributed on both sides of the middle positioning hole 11. In order to facilitate the processing of the positioning pins that cooperate with the positioning holes 11, the diameter of the positioning holes 11 is 1.5 to 2.5 mm.

[0041] Further, refer to Figure 1 The distances between the ends of the frame positioning strip 10 and the adjacent pins 20 are equal and greater than 0. That is, a section is reserved at both ends of the frame positioning strip 10 to strengthen the entire lead frame. The distance between the ends of the frame positioning strip 10 and the adjacent pins 20 is preferably 0.5 to 2 mm.

[0042] The lead frame of the MIPS of the present invention can be manufactured by the following two processes:

[0043] 1. Etching process: First, C194 (-1 / 2H) (chemical composition: Cu (≥97.0), Fe: 2.4, P: 0.03, Zn: 0.12) or KFC (-1 / 2H) (chemical composition: Cu (≥99.6), 0.05-0.15 (e.g. 0.1), P: 0.025-0.04 (e.g. 0.03)) and a substrate with a thickness of 0.5 mm are etched using etching chemicals to etch away unnecessary parts of the lead frame to obtain a lead frame of the desired structure; then, the etched lead frame is placed in a shaping mold to process the sinking sections of each pin of the lead frame and the V-shaped grooves on the pins to obtain a processed lead frame; finally, on the surface of the processed lead frame, nickel with a thickness of 0.1-0.5 um is first plated, and then tin with a thickness of 2-5 um is plated to complete the manufacture of the lead frame.

[0044] 2. Stamping process: First, C194 (-1 / 2H) (chemical composition: Cu (≥97.0), Fe: 2.4, P: 0.03, Zn: 0.12) or KFC (-1 / 2H) (chemical composition: Cu (≥99.6), Fe: 0.05-0.15 (e.g. 0.1), P: 0.025-0.04 (e.g. 0.03)), and a coil substrate with a thickness of 0.5mm, is sent into the stamping die through a stamping device, and the excess part of the lead frame substrate is first punched out and the pin sinking and V-groove processing are completed at the same time. Then, on the surface of the processed lead frame, nickel with a thickness of 0.1-0.5um is first plated, and then tin with a thickness of 2-5um is plated. The above steps have completed the lead frame processing.

[0045] Of course, the lead frame of the MIPS of the present invention can also be manufactured by other process methods.

[0046] The above description is only a partial or preferred embodiment of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.

Claims

1. A device for a semiconductor circuit, characterized in that include: A frame positioning strip, wherein a long side of the frame positioning strip has a plurality of pins extending vertically outward, each of the pins is arranged at intervals, and the tail end of the pin has a packaging section for fixing in a plastic package body, the packaging section includes a sinking section bent and arranged below the plane where the frame positioning strip is located, and the end of the sinking section is warped upward, the lower side of the warped portion of the sinking section is welded and fixed to a corresponding pad of a heat dissipation substrate provided with a circuit wiring layer, the downward bending angle of the sinking section ranges from 30° to 50°, and the end of the sinking section warps at an angle ranging from 3° to 5°; A reinforcing rib spans across and connects each of the pins, and the reinforcing rib is located between the packaging section and the frame positioning bar.

2. The device for a semiconductor circuit according to claim 1, characterized in that The width of the pin is 200 to 800 μm, and the distance between the center lines of two adjacent pins is one of 2.54 mm, 1.27 mm, 1.78 mm, 1 mm, 0.8 mm, 0.65 mm, 0.5 mm, and 0.4 mm.

3. The device for semiconductor circuit according to claim 2, characterized in that The lengths of the pins are equal.

4. The device for a semiconductor circuit according to claim 1, characterized in that The pins are arranged evenly at intervals, and the packaging sections of some of the pins are removed.

5. The device for a semiconductor circuit according to any one of claims 1 to 4, characterized in that The upper surface of the packaging section has a groove disposed adjacent to the sinking section.

6. The device for a semiconductor circuit according to claim 5, characterized in that There are multiple grooves, and the multiple grooves are distributed at intervals along the extension direction of the pin.

7. The device for a semiconductor circuit according to claim 6, characterized in that The groove is a V-shaped groove or a U-shaped groove extending along the length direction of the frame positioning strip.

8. The device for a semiconductor circuit according to claim 1, characterized in that The reinforcing rib is parallel to the frame positioning bar, and the reinforcing rib is arranged adjacent to the packaging section.

9. The device for a semiconductor circuit according to claim 1, characterized in that The frame positioning strip is provided with a plurality of positioning holes evenly spaced along its length direction. The distances between the two end portions of the frame positioning strip and the adjacent pins are equal and greater than 0.

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