Production process of anti-overflow lead frame

Abstract

The invention discloses a production process of an anti-overflow lead frame, and relates to the technical field of lead frame processing, and the production process comprises the following steps: stamping an outer lead V-shaped groove between two adjacent outer leads in the lead frame before blanking an outer lead hole; after the four right-angle sides of the waterproof groove of the slide glass square frame are stamped, the bevel edges of the waterproof groove of the slide glass square frame are stamped, and meanwhile, protruding structures are stamped on the step surfaces of the lug steps of the cooling fins and located on the outer sides of the bevel edges of the waterproof groove of the slide glass square frame. According to the invention, the stress of the material can be eliminated in advance, the change of the accumulated length of the whole lead frame is smaller after the inner lead and the outer lead are blanked, the plastic package material is effectively prevented from entering the lug step of the cooling fin in the subsequent plastic package process, the lug step of the cooling fin is prevented from being covered by the plastic package material, and the subsequent tinning of the product is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of lead frame processing, and in particular to a production process of an anti-overflow lead frame. Background Art

[0002] Lead frame is one of the main materials for semiconductor discrete devices and integrated circuit packaging. As the chip carrier of integrated circuits, lead frame is a key structural component that uses bonding materials (gold wire, aluminum wire, copper wire) to achieve electrical connection between the internal circuit lead end of the chip and the external lead to form an electrical circuit. It plays a bridge role with external wires. Lead frame is required in most semiconductor integrated blocks and is an important basic material in the electronic information industry. At present, semiconductor electronic components are usually assembled from chips, plastic packaging parts, gold wire or aluminum wire, and lead frames. In order to improve the efficiency of automated production, lead frames are generally arranged by multiple identical copper-based units, and each copper-based unit includes a heat sink, a carrier, inner leads and outer leads connected in sequence. The carrier is used to carry the chip of the electronic component, and the chip is encapsulated on the carrier after being encapsulated by the plastic packaging part.

[0003] However, when the lead frame is plastic-sealed, there is a gap between the punching collapse angles on the left and right surfaces of the heat sink area of ​​the lead frame and the plastic-sealing mold. Therefore, the plastic-sealing material will enter the gap during the plastic-sealing process, resulting in overflow on the surface partition wall of the heat sink area of ​​the semiconductor lead frame (the quality control standard is that it cannot exceed 0.3mm). The presence of overflow on the heat sink surface will prevent the semiconductor chip from being coated in this area later. After the plastic falls off, the material of the lead frame will be exposed, affecting the performance of the semiconductor chip.

[0004] In order to solve the above problems, lead frames with anti-overflow function are currently proposed on the market, such as Figure 1 , Figure 2 As shown, during the production of the lead frame, on the one hand, the cumulative length of the entire lead frame may change due to the copper tape being easily changed during the process of stamping the inner leads and the outer leads, which may not only cause difficulty in feeding during subsequent use, but may also cause deformation of the inner leads; on the other hand, during the stamping process of the carrier, the portion of the edge of the carrier corresponding to the oblique side of the carrier frame waterproof groove is prone to collapse and produce an arc angle, which makes it easy to produce overflow during the subsequent plastic sealing process. The overflow will cover the heat sink ear step, resulting in the inability to effectively tin the heat sink ear step during subsequent tinning. Summary of the invention

[0005] The purpose of the present invention is to provide a production process for an anti-overflow lead frame, which can not only eliminate the stress of the material in advance, so that the cumulative length change of the inner lead and the outer lead of the entire lead frame after punching is smaller, but also effectively prevent the plastic sealing material from entering the heat sink ear step during the subsequent plastic sealing process, avoid the plastic sealing material from covering the heat sink ear step, and ensure the subsequent tinning of the product.

[0006] To achieve the purpose of the present invention, the technical solution adopted is: a production process of an anti-overflow lead frame, comprising the following steps:

[0007] Punching an outer lead V-shaped groove between two adjacent outer leads in the lead frame before punching the outer lead hole;

[0008] After punching the four right-angled sides of the wafer carrier frame waterproof groove, the oblique side of the wafer carrier frame waterproof groove is punched while punching the protruding structure on the step surface of the heat sink ear step, and the protruding structure is located outside the oblique side of the wafer carrier frame waterproof groove.

[0009] Furthermore, a punch for punching the protruding structure has a V-shaped tooth matched with the protruding structure, and the center of the V-shaped tooth is flush with the riser surface of the heat sink ear step.

[0010] Furthermore, the second punch for punching the V-shaped groove of the external lead has V-groove teeth adapted to the V-shaped groove of the external lead.

[0011] Furthermore, there is a certain distance between the inner end of the V-shaped groove of the outer lead and the middle rib of the lead frame, and the outer end of the V-shaped groove of the outer lead passes through the bottom rib of the lead frame.

[0012] Furthermore, the pre-punched dividing strip holes are pre-punched before the V-shaped grooves of the external leads are punched.

[0013] Furthermore, after punching the external lead V-shaped groove and before punching the protruding structure, the pre-punched chip carrier hole and the edge strip are punched in sequence, and the four right-angled sides of the chip carrier frame waterproof groove are punched.

[0014] Furthermore, the pre-punched wafer carrier hole is in a "convex" shape, and the width of the pre-punched wafer carrier hole at one end away from the inner lead is smaller than the width of the pre-punched wafer carrier hole at one end close to the inner lead.

[0015] Furthermore, the stamping of the right-angled sides of the wafer carrier frame waterproof groove is completed in two steps: the first time is to stamp the horizontal side of the wafer carrier frame waterproof groove, and the second time is to stamp the vertical side of the wafer carrier frame waterproof groove. The horizontal side of the wafer carrier frame waterproof groove is stamped with the inner lead double V groove at the same time, and the oblique side and protruding structure of the wafer carrier frame waterproof groove are stamped with the outer lead hole at the same time.

[0016] Furthermore, after the outer lead hole is punched out, the M-shaped hole, inner lead hole, hook needle hole and frame positioning hole are punched out in turn. While the frame positioning hole is punched out, the side strip is finely punched out, and the finely punched carrier hole and finely punched dividing strip hole are finely punched out in turn, the outer periphery of the carrier is upset, the glue locking hole is punched out, and the carrier strip groove is punched out.

[0017] Furthermore, the punch three for punching the glue locking hole includes a fixed section, a reinforcement section and a punching section, and the length of the punching section is 6 mm; the unloading insert for punching the glue locking hole is installed on the unloading plate, and the unloading insert includes an insert B and an insert A arranged in an upper and lower manner, and the insert B is provided with a guide hole that cooperates with the reinforcement section, and the insert A has a guide hole that cooperates with the punching section.

[0018] The beneficial effects of the present invention are:

[0019] 1. In the present invention, by punching an outer lead V-shaped groove between two adjacent outer leads, the stress of the material can be eliminated in advance, so that the cumulative length change of the entire lead frame after the inner lead and the outer lead are smaller.

[0020] 2. In the present invention, a protruding structure is stamped on the edge of the carrier and on the outer side of the oblique edge of the waterproof groove of the carrier frame to reduce the problem of arc angle caused by the collapse of the edge of the carrier during fine punching, so that in the subsequent plastic sealing process, the edge of the plastic sealing mold and the heat sink can be better fitted, and the plastic sealing material will not leak during the plastic sealing process, thereby effectively preventing the plastic sealing material from entering the heat sink ear step during the subsequent plastic sealing process, avoiding the plastic sealing material from covering the heat sink ear step, and ensuring the subsequent tinning of the product.

[0021] 3. By setting the pre-punched carrier hole to a "convex" shape, the mold can better press the carrier during fine-punching the carrier to avoid displacement of the material strip.

[0022] 4. By setting the unloading insert into a structure of insert A and insert B, and shortening the punching section on the punch three for punching the glue lock hole to 6mm, the punch three for punching the glue lock hole can be effectively prevented from breaking; at the same time, the punching of the glue lock hole is set at the rear section of the entire mold to prevent the punch three for punching the glue lock hole from breaking and affecting other workstations. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings illustrate exemplary embodiments of the present invention and together with the description serve to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification.

[0024] Figure 1 It is the main view of the lead frame with the flash function;

[0025] Figure 2 is a side view of the lead frame with flash function;

[0026] Figure 3 is a cross-sectional view of a metal strip;

[0027] Figure 4 It is a schematic diagram of the material strip structure of the anti-overflow lead frame;

[0028] Figure 5 It is a production step diagram of an anti-overflow lead frame;

[0029] Figure 6 yes Figure 4 Sectional view of AA in the middle;

[0030] Figure 7 is a side view of the second punch;

[0031] Figure 8 yes Figure 7 A partial enlarged view of part B;

[0032] Fig. 9 is a top view of the punch 1;

[0033] Fig.10 yes Fig. 9 Schematic cross-section of the CC;

[0034] Fig.11 It is a partial schematic diagram of the anti-overflow lead frame before the protruding structure is punched;

[0035] Fig.12 It is a partial schematic diagram of the anti-overflow lead frame after the protruding structure is stamped;

[0036] Fig.13 It is a schematic diagram of the structure of the M-type punch;

[0037] Fig.14 It is a structural schematic diagram of the stamping state of the M-type punch;

[0038] Fig.15 This is the installation diagram of punch three.

[0039] Markings and corresponding parts names in the attached drawings:

[0040] 1. Inclined positioning block, 2. Pre-punched dividing strip hole, 3. External lead V-shaped groove, 4. Pre-punched carrier hole, 5. Side strip, 6. Positioning notch, 7. Positioning pin, 8. Horizontal side of the carrier square waterproof groove, 9. Vertical side of the carrier square waterproof groove, 10. Bevel side of the carrier square waterproof groove, 11. Raised structure, 12. Hook needle hole, 13. M-shaped hole, 14. Inner lead hole, 15. Inner lead double V-groove, 16. External lead hole, 17. Frame positioning hole, 18. Carrier, 19. Peripheral upsetting table, 20. Glue locking hole, 21. Carrier strip groove, 22. Distortion correction strip, 23. Cumulative step correction block, 24. Fine-punched dividing strip hole, 25. Fine-punched carrier hole;

[0041] 301, punch 2, 302, V-groove teeth;

[0042] 1101, punch 1, 1102, V-shaped teeth;

[0043] 1301, M-shaped punch, 1302, inclined step, 1303, cutting edge;

[0044] 2001. Punch three, 2002. Insert B, 2003. Insert A. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with the accompanying drawings and implementation methods. It is understood that the specific implementation methods described herein are only used to explain the relevant content, rather than to limit the present invention. It is also necessary to explain that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings.

[0046] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0047] The present invention provides a production process for an anti-overflow lead frame, which is mainly a processing process for processing existing metal strips, such as Figure 3 As shown, the width direction of the metal strip is consistent with the length direction of the lead frame to be processed, the metal strip is thin at both sides and thick in the middle, the middle of the metal strip is referred to as thick material, and the two sides of the metal strip are referred to as thin material, the upper surface of the thick material is flush with the upper surface of the thin material, and the lower surface of the thick material is transitioned to the lower surface of the thin material through a step slope, and the step slope is connected to the lower surface of the thick material through an arc angle. When the metal strip is processed, the lead frame is symmetrically arranged along the central axis of the metal strip, the thin material is used to process the inner lead and the outer lead, and the thick material is used to process the carrier 18; in the process of processing the lead frame, the lower surface of the metal strip is supported on the die, and specifically, the processing of the anti-overflow lead frame includes the following steps:

[0048] S1: Pre-punch the pre-punched dividing strip hole 2, the central axis of the pre-punched dividing strip hole 2 is in the same straight line with the central axis of the metal strip, that is, the pre-punched dividing strip hole 2 is located between two lead frames of the same width of the metal strip; at the same time, the pre-punched dividing strip hole 2 is a rectangular hole, and the pre-punched dividing strip hole 2 is located outside the carrier 18, such as Figure 4 , Figure 5By punching out the rectangular pre-punched dividing strip hole 2, the fine punching margin of the pre-punched dividing strip hole 2 is reduced, thereby reducing the punching force, avoiding the appearance of the heat sink such as corner collapse, distortion, etc. caused by excessive extrusion deformation of the lead frame during fine punching of the subsequent fine punching dividing strip hole 24; at the same time, the pre-punched dividing strip hole 2 also serves as a positioning hole for subsequent processing of the metal strip.

[0049] S2: stamping an outer lead V-shaped groove 3 on the thin material of the metal strip, the axial direction of the outer lead V-shaped groove 3 is consistent with the width direction of the metal strip, in order to avoid affecting the outer lead on the lead frame, the position of the outer lead V-shaped groove 3 on the metal strip should avoid the position where the outer lead is formed, so the outer lead V-shaped groove 3 can be arranged between two adjacent outer leads; in order to avoid the outer lead V-shaped groove 3 affecting the middle rib on the lead frame, a certain distance should be kept between the inner end of the outer lead V-shaped groove 3 and the middle rib on the lead frame; because the bottom rib of the lead frame needs to be cut off when in use, the outer end of the outer lead V-shaped groove 3 can extend to the edge of the metal strip, such as Figure 4 , Figure 5 , Figure 7 , Figure 8 shown.

[0050] In order to punch the outer lead V-shaped groove 3, the second punch 301 on the die for punching the outer lead V-shaped groove 3 has V-shaped teeth 302, and the axial direction of the V-shaped teeth 302 is consistent with the length direction of the lead frame. By punching the outer lead V-shaped groove 3, the stress of the material can be eliminated in advance, so that the cumulative length change of the entire lead frame after punching the inner and outer leads is smaller.

[0051] S3: Pre-punch the pre-punched wafer hole 4, the central axis of the pre-punched wafer hole 4 is consistent with the width direction of the metal strip, and the pre-punched wafer hole 4 is located between the two lead frames on the same side of the metal strip; the pre-punched wafer hole 4 is "convex", the end of the pre-punched wafer hole 4 with a smaller width extends toward the central axis of the metal strip, and the end of the pre-punched wafer hole 4 with a larger width extends toward the external lead. By pre-punching the pre-punched wafer hole 4, after the subsequent fine-punching of the fine-punched wafer hole 25, the two side surfaces of the wafer 18 are at right angles, so that the collapse angle of the surface of the wafer 18 is small, and the surface of the wafer 18 after plastic sealing is reduced. Since the pre-punched carrier hole 4 is located between the two lead frames on the same side of the metal strip, after the pre-punching of the pre-punched carrier hole 4 is completed, a connecting rib is still retained between the two pre-punched carrier holes 4 located on the same width of the metal strip. The width of the connecting rib is 1.3mm. Although the strength is poor, it can still connect the two lead frames on the same width of the metal strip, avoiding the problem that the mold cannot hold down the carrier 18 during subsequent fine punching due to the carrier 18 not being connected on the left and right, resulting in displacement and further damage to the convex and concave die cutting edges.

[0052] S4: Punch out edge strips 5 on both sides of the metal strip. The width of the metal strip after punching out the edge strips 5 is smaller than the original width of the metal strip. At the same time, after punching out the edge strips 5 on both sides of the metal strip, both sides of the metal strip have positioning notches 6, which not only enable the metal strip to be guided by the positioning notches 6 during the forward movement, but also enable the metal strip to enter the next workstation more accurately.

[0053] S5: Punch the horizontal side 8 of the square groove of the carrier 18, and punch the inner lead double V groove on the inner lead at the same time, and the axial direction of the inner lead double V groove is consistent with the width direction of the inner lead; after the horizontal side 8 of the square groove of the carrier 18 and the inner lead double V groove are punched, punch the vertical side 9 of the square groove of the carrier 18. Since the one-time processing of the "mouth" type structure will lead to poor strength and easy damage of the processed workpiece; in the present invention, the horizontal side 8 of the square groove of the carrier 18, the vertical side 9 of the square groove of the carrier 18 and the oblique side 10 of the punched carrier frame waterproof groove are punched separately, thereby improving the strength of the workpiece. In the present invention, punching the inner lead double V groove before punching the outer lead hole 16 will not affect the dimensional accuracy of the inner lead.

[0054] S6: Punch the bevel 10 of the stamped wafer carrier square frame waterproof groove. The bevel 10 of the stamped wafer carrier square frame waterproof groove is used to connect the horizontal side 8 of the wafer carrier 18 square frame groove and the vertical side 9 of the wafer carrier 18 square frame groove. Since the side of the wafer carrier 18 square frame groove close to the inner lead is not provided with a bevel, there are two bevels in one wafer carrier 18 square frame groove. Since there are two lead frames of the same width on the metal strip, the bevels in the wafer carrier 18 square frame grooves on the two lead frames can be punched at the same time. Figure 4 , Figure 5 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 shown.

[0055] When punching the bevel 10 of the waterproof groove of the wafer carrier frame, a protruding structure 11 is punched on the heat sink ear step. The protruding structure 11 is located outside the bevel 10 of the waterproof groove of the wafer carrier frame, so that the heat sink ear step has a fence higher than the surface of the heat sink ear step, so that the plastic packaging material of the wafer carrier 18 cannot overflow through the heat sink ear step during the subsequent plastic packaging process, thereby ensuring the quality of tin plating.

[0056] In the present invention, in order to facilitate the stamping of the raised structure 11, a V-shaped tooth 1102 is provided on a punch 1101 for stamping the raised structure 11, and the length direction of the V-shaped tooth 1102 is consistent with the width of the metal strip, and the center axis of the V-shaped tooth 1102 is on the same plane as the riser surface of the heat sink ear step, so that when the V-shaped tooth 1102 is stamped, as the punch 1101 with the V-shaped tooth 1102 moves downward, the side of the V-shaped tooth 1102 squeezes the riser surface of the heat sink ear step, so that the riser surface of the heat sink ear step extends upward, so that the edge of the heat sink ear step forms a raised structure 11, which can effectively reduce the problem of the edge of the carrier 18 collapsing to produce an arc angle when punching the carrier hole 25.

[0057] During the process of punching the vertical side 9 of the square groove of the wafer carrier 18 and the oblique side 10 of the waterproof groove of the wafer carrier frame, the external lead hole 16 is punched. By setting the punching of the external lead hole 16 and the punching of the square groove of the wafer carrier 18 at the same station, the length of the mold can be shortened, and the impact of the side bending of the metal strip on the punching position of the M-shaped punch 1301 can be reduced.

[0058] S7: Punching an M-shaped hole 13, the M-shaped hole 13 is located between the inner lead and the carrier 18, and the punch for punching the M-shaped hole 13 is also M-shaped, such as Figure 4 , Figure 5 , Fig.13 , Fig.14 As shown, the punch is called an M-type punch 1301. The M-type punch 1301 cuts the junction between thick and thin materials while punching the M-type hole 13. In order to ensure that the distance between the M-type punch 1301 and the step slope on the metal strip is more stable, a positioning pin 7 corresponding to the pre-punched pre-punched dividing strip hole 2 is also provided on the mold, and there are two positioning pins 7, and the two positioning pins 7 and the punching of the M-type hole 13 are located at the same station.

[0059] The M-shaped punch 1301 for punching the M-shaped hole 13 in the present invention is provided with four inclined steps 1302. Specifically, the M-shaped punch 1301 includes a horizontal portion and three extension portions. The axial directions of the three extension portions are perpendicular to the axial direction of the horizontal portion. One of the extension portions is located in the middle of the horizontal portion, and the other two extension portions are located at both ends of the horizontal portion. The two inclined steps 1302 are respectively located at the two shoulders of the M-shaped punch 1301. The shoulders here refer to the horizontal portion of the M-shaped punch 1301 and the M-shaped punch 1301. 01, at the same time, the middle extension part of the M-shaped punch 1301 is M-shaped, and the other two inclined steps 1302 are located on the step surface of the middle extension part, so that the waste material will not move upward during the processing of the M-shaped punch 1301, thereby effectively preventing the waste material from moving upward when the horizontal part of the M-shaped punch 1301 moves upward and causing damage to the step inclined surface at the connection between the thick material and the thin material. Through the cooperation of the four inclined steps 1302, the waste material will not move upward and scrape the step inclined surface at the connection between the thick material and the thin material.

[0060] In the present invention, Fig.13 As shown, the cutting edge 1303 of the M-type punch 1301 protrudes upward, and the height of the cutting edge 1303 of the M-type punch 1301 is 0.6 to 1.0 times the thickness of the side of the metal strip, and the angle of the cutting edge 1303 of the M-type punch 1301 protruding upward is 10° to 20°, ensuring that when the cutting edge 1303 of the punch punches through the material, the planar area of ​​the punch is still connected, so that the waste material will not move to the thick material area, the distance between the waste material and the thick material will be increased, and the waste material will be forced to be pulled toward the thin material side, and no copper wire will appear.

[0061] S8: Punching the inner lead hole 14 and the hook needle hole 12, and the inner lead hole 14 and the hook needle hole 12 are completed at the same station, which can improve the product precision.

[0062] While punching the inner lead hole 14 and the hook hole 12, the side strip 5 is finely punched and the frame positioning hole 17 is punched. The frame positioning hole 17 is located on the bottom rib of the lead frame. The fine punching of the side strip 5 and the punching of the frame positioning hole 17 are set at the same station, which can effectively improve the product precision.

[0063] S9: Punching and fine-punching the wafer carrier hole 25. Here, the fine-punching position of the wafer carrier hole 25 is the part outside the raised structure 11 in step 6. The mold for fine-punching the wafer carrier hole 25 is also provided with positioning pins 7 corresponding to the pre-punched pre-punched dividing strip holes 2.

[0064] S10: Punching the fine-blanking dividing strip hole 24. By placing the fine-blanking of the fine-blanking carrier hole 25 before the fine-blanking of the fine-blanking dividing strip hole 24, during the fine-blanking process of the fine-blanking carrier hole 25, there is still a connecting rib between the two fine-blanking carrier holes 25 on the same width of the metal strip, so that the mold can press the two carriers 18 on the same width of the metal strip during the punching of the fine-blanking carrier hole 25, avoiding displacement of the two carriers 18 on the same width of the metal strip. The metal strip is divided into two strips by punching the fine-blanking dividing strip hole 24. By placing this step before the upsetting table 19 for upsetting the outer periphery of the carrier 18, it is ensured that the upper and lower steps on the mold can penetrate the gap between the two metal strips when the carrier 18 is upset.

[0065] S11: Upset the steps on the left side of the carrier 18, the right side of the carrier 18, and the side of the carrier 18 close to the inner lead. During the upsetting process, a punch is used on the front side of the lead frame as the load-bearing surface when upsetting the steps on the side of the carrier 18 close to the inner lead. The force of the punch comes from the punching machine, which can not only press the carrier 18 more stably, but also provide more sufficient upsetting force and more stable product size.

[0066] S12: Punch a glue locking hole 20 on the inner lead, such as Figure 4 , Figure 5 , Fig.14 , Fig.15 As shown. Since the size of the glue locking hole 20 is very small, the size of the punch 3 2001 used for punching the glue locking hole 20 is relatively small. When designing the punch 3 2001, if the punch 3 2001 is too long, it is easy to break during the punching process of the glue locking hole 20. The punch three 2001 in the present invention includes a fixed section, a reinforcement section and a punching section. The punching section is the part of the punch three 2001 used for punching the glue locking hole 20. Therefore, the size of the punching section is adapted to the size of the glue locking hole 20. In order to prevent the punch three 2001 from breaking, the length of the punching section can be designed to be 6 mm. The sizes of the fixed section and the reinforcement section are both larger than the diameter of the punching section. During installation, the fixed section is installed on the punch fixing plate, and the reinforcement section passes through the unloading back plate. The unloading insert for punching the glue locking hole 20 includes an insert B2002 and an insert A2003 arranged in an upper and lower manner. The insert B2002 is located on the insert A2003, and a guide hole matching the reinforcement section is provided on the insert B2002. The insert A2003 has a guide hole matching the punching section. This design method can reduce the length of the punching section as much as possible. In order to ensure that the punch three 2001 punches the glue locking hole 20, the guide hole is a stepped hole, the diameter of the guide hole close to the insert B2002 is larger than the diameter of the guide hole away from the insert B2002, and the diameter of the guide hole close to the insert B2002 is larger than the size of the guide hole on the insert B2002, and the opening on the stepped surface of the guide hole is a bell mouth.

[0067] Since the punch three 2001 is too small and easy to break, the punching of the glue locking hole 20 is arranged in the rear section of the mold in the present invention to be completed, which can effectively prevent the punch three 2001 from affecting other workstations of the mold due to sudden breakage. Therefore, the punch three 2001 is placed in a place with fewer workstations.

[0068] S13: Punching the wafer strip groove 21 on the wafer 18 to complete the punching of the lead frame. The direction of the wafer strip groove 21 is consistent with the length direction of the metal strip, and the wafer strip groove 21 is evenly distributed on the wafer 18. The punching of the wafer strip groove 21 is completed in the rear section of the mold because the flatness of the metal strip at the rear section is better, and the depth of the pressed wafer strip groove is more uniform and can be better controlled within 5 to 12 microns.

[0069] When the wafer carrier strip groove 21 on the lead frame is punched, the lead frame has been punched. However, in order to prevent the lead frame strip from twisting after punching, a twist correction strip 22 with an inclination is provided at the rear section of the mold to correct the lead frame strip to be flat. In order to ensure that the cumulative step of the lead frame strip meets customer requirements, a cumulative step correction block 23 with an adjustable cumulative step is provided at the rear section of the mold. There are two cumulative step correction blocks 23, one of which corresponds to the bottom rib of the lead frame, and the other of which corresponds to the middle rib of the lead frame.

[0070] In the present invention, before the metal strip enters the mold and before pre-punching the pre-punching material strip hole 2, two inclined positioning blocks 1 can be installed on the die, such as Figure 4 , Figure 6 As shown, the two inclined surface positioning blocks 1 are in close contact with the two stepped inclined surfaces on the metal strip respectively, so that the center of the thick material on the metal strip is fixed at the center of the die, the position of the punching pre-punching dividing strip hole 2 is more accurate, and the probability of copper wire appearing at the cutting position where the thick material and the thin material are connected by the M-shaped punch 1301 is smaller.

[0071] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0072] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0073] It should be understood by those skilled in the art that the above embodiments are only for the purpose of clearly illustrating the present invention, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present invention.

Claims

1. A production process for an anti-overflow lead frame, characterized in that: The steps include: Punching an external lead V-shaped groove (3) between two adjacent external leads in the lead frame before punching the external lead hole; After the four right-angled sides of the wafer carrier square waterproof groove are punched, the oblique side (10) of the wafer carrier square waterproof groove is punched and at the same time, a protruding structure (11) is punched on the step surface of the heat sink ear step, and the protruding structure (11) is located outside the oblique side (10) of the wafer carrier square waterproof groove.

2. The production process of the anti-overflow lead frame according to claim 1, characterized in that: A punch (1101) for punching the protruding structure (11) has a V-shaped tooth (1102) adapted to the protruding structure (11), and the center of the V-shaped tooth (1102) is flush with the riser surface of the heat sink ear step.

3. The production process of the anti-overflow lead frame according to claim 1, characterized in that: The second convex die (301) for punching the external lead V-shaped groove (3) is provided with V-groove teeth (302) adapted to the external lead V-shaped groove (3).

4. The production process of the anti-overflow lead frame according to claim 1, characterized in that: There is a certain distance between the inner end of the external lead V-shaped groove (3) and the middle rib of the lead frame, and the outer end of the external lead V-shaped groove (3) penetrates the bottom rib of the lead frame.

5. The production process of the anti-overflow lead frame according to claim 1, 2, 3 or 4, characterized in that: The pre-punched dividing strip hole (2) is pre-punched before punching the external lead V-shaped groove (3).

6. The production process of the anti-overflow lead frame according to claim 1, 2, 3 or 4, characterized in that: After punching the external lead V-shaped groove (3) and before punching the protruding structure (11), the pre-punched chip carrier hole (4) and the side strip (5) are punched in sequence, and the four right-angled sides of the chip carrier frame waterproof groove are punched.

7. The production process of the anti-overflow lead frame according to claim 6, characterized in that: The pre-punched chip carrier hole (4) is convex, and the width of the pre-punched chip carrier hole (4) at one end away from the inner lead is smaller than the width of the pre-punched chip carrier hole (4) at one end close to the inner lead.

8. The production process of the anti-overflow lead frame according to claim 6, characterized in that: The punching of the right-angled side of the wafer carrier square frame waterproof groove is completed in two steps. The first step is to punch the horizontal side (8) of the wafer carrier square frame waterproof groove, and the second step is to punch the vertical side (9) of the wafer carrier square frame waterproof groove. The horizontal side (8) of the wafer carrier square frame waterproof groove is punched with an inner lead double V groove (15) while punching. The oblique side (10) and the protruding structure (11) of the wafer carrier square frame waterproof groove are punched with an outer lead hole (16) while punching.

9. The production process of the anti-overflow lead frame according to claim 8, characterized in that: After the outer lead hole (16) is punched, the M-shaped hole (13), the inner lead hole (14), the hook needle hole (12), and the frame positioning hole (17) are punched in sequence. While the frame positioning hole (17) is punched, the side strip (5) is finely punched, and the finely punched carrier hole (25) and the finely punched material dividing strip hole (24) are finely punched in sequence. The outer periphery of the carrier is upset (19), the glue locking hole (20) is punched, and the carrier strip groove (21) is punched.

10. The production process of the anti-overflow lead frame according to claim 9, characterized in that: The punch three (2001) for punching out the glue locking hole (20) comprises a fixing section, a reinforcing section and a punching section, and the length of the punching section is 6 mm; the unloading insert for punching out the glue locking hole (20) is installed on the unloading plate, and the unloading insert comprises an insert B (2002) and an insert A (2003) arranged in an upper and lower manner, and a guide hole cooperating with the reinforcing section is opened on the insert B (2002), and a guide hole cooperating with the punching section is provided on the insert A (2003).

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