Electromagnetic packaging mold for semiconductor circuit and semiconductor manufacturing method using the same

Abstract

This invention provides an electromagnetic packaging mold for semiconductor circuits and a semiconductor manufacturing method using the same. The semiconductor circuit includes a metal substrate; multiple circuit components disposed at specific locations on the metal substrate; bonding metal wires for electrically connecting the multiple circuit components; a lead frame for connecting to the metal substrate and extending outwards as input / output; a molding compound covering the metal substrate, the molding compound at least sealing the connection portion between the lead frame and the metal substrate; movable pins embedded in the molding compound and pressed against the metal substrate; the packaging mold includes a mold body, the mold body having a lead frame movement space for the exposed portion of the lead frame; an upper electromagnet and a lower electromagnet are respectively attached to opposite sides of the lead frame movement space. This invention can solve the problems of insulating layer delamination, reducing substrate tolerances, and solving the problem of adhesive overflow on the substrate and lead frame.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to an electromagnetic packaging mold for semiconductor circuits and a semiconductor manufacturing method using the same. Background Technology

[0002] The industry standard for aluminum substrate thickness tolerance is ±10%. Such a large tolerance makes it impossible for the aluminum substrate and the mold to achieve a precise fit, resulting in overflow in the semi-encapsulated semiconductor circuit.

[0003] Currently, the main solutions for preventing overflow in semi-encapsulated semiconductor circuits, both domestically and internationally, are as follows: 1. Ejector pins: Ejector pins are added to the mold cavity to press the aluminum substrate tightly against the cavity surface; 2. Mechanical grinding: The overflowing surface of the aluminum substrate is mechanically ground using relevant grinding equipment; 3. Laser engraving: The overflowing surface of the aluminum substrate is engraved using laser equipment. However, these three methods can cause cracks in the insulating layer, damage the anodized layer on the metal substrate surface, and result in low efficiency and incomplete removal of the overflowing adhesive.

[0004] Therefore, there is a need for a semiconductor circuit and its manufacturing method that can solve the problems of insulating layer delamination, reduce substrate tolerance, and solve the problem of adhesive overflow on the substrate and lead frame. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing an electromagnetic packaging mold for semiconductor circuits and a semiconductor manufacturing method using the same. This mold can solve the problems of insulating layer delamination, reduce substrate tolerance, and resolve adhesive overflow issues on the substrate and lead frame.

[0006] To address the aforementioned technical problems, in a first aspect, embodiments of the present invention provide an electromagnetic packaging mold for semiconductor circuits, comprising:

[0007] The semiconductor circuit includes a metal substrate; a plurality of circuit components disposed at specific locations on the metal substrate; bonding metal wires for electrically connecting the plurality of circuit components; a lead frame for connecting to the metal substrate and extending outward as an input / output; a molding compound covering the metal substrate, the molding compound at least sealing the connection portion between the lead frame and the metal substrate, and at least a portion of the outwardly extending lead frame is not sealed and is exposed; movable pins embedded in the molding compound and pressed against the metal substrate; the packaging mold includes a mold body, the mold body providing a lead frame movement space for the exposed portion of the lead frame; an upper electromagnet and a lower electromagnet are respectively attached to opposite sides of the lead frame movement space, the upper electromagnet and the lower electromagnet being used to clamp the lead frame during mold closing.

[0008] Preferably, the metal substrate includes a metal substrate, an insulating layer, a copper foil layer, and a protective layer. The insulating layer is attached to one side of the metal substrate, the copper foil layer is pressed onto the side of the insulating layer away from the metal substrate, and the protective layer is attached to the side of the copper foil layer away from the insulating layer.

[0009] Preferably, the metal substrate has a curved surface.

[0010] Preferably, the copper foil layer is formed into a circuit wiring layer by etching.

[0011] Preferably, the lead frame is made of copper alloy.

[0012] Preferably, the circuit components include surface mount capacitors, surface mount resistors, and other components, which are respectively mounted on the metal substrate.

[0013] Preferably, the upper electromagnet and the lower electromagnet are attached between the molding compound and the movable space of the lead frame.

[0014] Preferably, the lead frame and the metal substrate are electrically connected by lead soldering.

[0015] Preferably, the mold body includes an upper mold and a lower mold. The upper mold has an upper groove formed by a recess on one side near the lead frame, and the lower mold has a lower groove formed by a recess on the other side near the lead frame. The upper mold and the lower mold are fitted together so that the upper groove and the lower groove are correspondingly arranged to form the movable space of the lead frame.

[0016] Secondly, the present invention also provides a method for manufacturing a semiconductor circuit, including the semiconductor circuit described in any of the above embodiments, the semiconductor manufacturing method comprising the following steps:

[0017] S1. The metal substrate is placed on a special carrier by automated equipment or manual labor.

[0018] S2. The semiconductor inverter circuit chip is mounted onto the component mounting position reserved in the copper foil layer of the metal substrate by applying solder paste or applying silver glue through an automatic die bonding device.

[0019] S3. High-voltage power devices are mounted onto silver-plated copper heat sinks using a soft solder die bonder to form semi-finished components.

[0020] S4. Using an automated surface mount technology (SMT) device to reduce resistance and capacitance, the semi-finished components are mounted onto the component mounting positions.

[0021] S5. The lead frame is placed on the corresponding welding position of the metal substrate by a robot or manually, the metal substrate including the special carrier is passed through the reflow oven, and all the circuit components are welded to the corresponding mounting positions.

[0022] S6. The soldering quality of the circuit components is inspected by visual inspection AOI equipment, and flux and aluminum shavings remaining on the metal substrate are removed by spraying and ultrasonication.

[0023] S7. The circuit components and the circuit wiring layer are electrically connected through the bonding metal wire;

[0024] S8. The metal substrate circuit is encapsulated in a specific mold using packaging equipment, and then marked by laser marking.

[0025] S9. Post-curing stress relief treatment is carried out in a high-temperature oven;

[0026] S10. The connecting ribs and dummy pins of the pins are cut off and shaped into the required shape using a rib cutting and forming equipment. Finally, electrical parameter testing is performed to form the final qualified product.

[0027] Compared to existing technologies, this invention absorbs the combined tolerances of the aluminum substrate (±10%), lead frame welding tolerances, and mold tolerances through the lead frame's movable space. This ensures no stress is generated between the substrate and the lead frame. Simultaneously, the energization of the upper and lower electromagnets clamps the lead frame, preventing molding compound from flowing into the lead frame's movable space and causing the risk of lead frame overflow. These methods solve both the problem of insulation layer cracking caused by stress and the problem of molded compound overflow between the substrate and the lead frame, thus improving the reliability of semiconductor circuits. Attached Figure Description

[0028] The present invention will now be described in detail with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and more readily understood through the detailed description following the accompanying drawings. In the drawings:

[0029] Figure 1 This is a schematic diagram of the electromagnetic packaging mold structure of the semiconductor circuit provided by the present invention (mold closed state);

[0030] Figure 2 This is a schematic diagram of the electromagnetic packaging mold structure of the semiconductor circuit provided by the present invention (mold open state);

[0031] Figure 3 This is a schematic diagram of a semiconductor circuit structure with gap contacts in the prior art;

[0032] Figure 4 It is a schematic diagram of a semiconductor circuit structure that has been used in existing technologies;

[0033] Figure 5 This is a schematic diagram of a semiconductor circuit structure with normal contact in the prior art;

[0034] Figure 6 This is a schematic diagram of the semiconductor circuit metal substrate structure provided by the present invention;

[0035] Figure 7 This is a flowchart of the semiconductor circuit manufacturing method provided by the present invention. Detailed Implementation

[0036] The specific embodiments / examples described herein are specific implementations of the present invention, used to illustrate the concept of the invention, and are illustrative and exemplary, and should not be construed as limiting the implementation or scope of the invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein, all of which are within the protection scope of the present invention.

[0037] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] (Example 1)

[0039] Please refer to Figures 1-6 As shown, the present invention provides a semiconductor circuit, comprising:

[0040] Aluminum substrate 6; a plurality of circuit components (not shown in the figure) disposed at specific locations on the aluminum substrate 6; bonding metal wires 9 for realizing electrical connections between the plurality of circuit components; lead frames 4 for connecting to the aluminum substrate 6 and extending outward as inputs and outputs; a molding compound 3 covering the aluminum substrate 6, the molding compound 3 at least sealing the connection portion between the lead frames 4 and the aluminum substrate 6, and at least a portion of the outwardly extending lead frames 4 is not sealed and is exposed; movable pins 2 embedded in the molding compound 3 and pressed against the aluminum substrate 6.

[0041] The packaging mold for encapsulating the semiconductor circuit of the present invention includes a mold body (not shown in the figure), an upper electromagnet 102 and a lower electromagnet 101; the packaging mold provides a lead frame movable space 103 for the exposed portion of the lead frame 4; the upper electromagnet 102 and the lower electromagnet 101 are respectively attached to opposite sides of the lead frame movable space 103, and the upper electromagnet 102 and the lower electromagnet 101 are used to clamp the lead frame 4 when the mold is closed.

[0042] The molding compound 3 is a powdered molding compound made of epoxy resin as the base resin, high-performance phenolic resin as the curing agent, silicon micro powder and other fillers, and various additives. It is extruded into the mold cavity by heat transfer molding and embeds the semiconductor chip therein. At the same time, it is cross-linked and cured to form a device with a certain shape and structure. The bonding metal wire 9 is made of any one of gold, aluminum and copper.

[0043] In this embodiment of the invention, the aluminum substrate 6 includes an aluminum substrate 01, an insulating layer 02, a copper foil layer 03, and a protective layer 04. The insulating layer 02 is attached to one side of the aluminum substrate 01, the copper foil layer 03 is pressed onto the side of the insulating layer 02 away from the aluminum substrate 01, and the protective layer 04 is attached to the side of the copper foil layer 03 away from the insulating layer 02. Specifically, the aluminum substrate 01 serves as the carrier of the entire internal circuit of the semiconductor circuit and also provides heat dissipation for the entire semiconductor circuit; the insulating layer 02 is used to prevent short circuits and leakage risks caused by the circuit wiring layer being energized with the aluminum substrate 01; the protective layer 04 is used to prevent soldering in places where it should not be soldered, increase the withstand voltage between circuits, prevent short circuits caused by circuit oxidation or contamination, and protect the circuit.

[0044] In this embodiment of the invention, the aluminum substrate 01 is curved. Specifically, since the semiconductor circuit provided by this invention needs to detect the vibration of the compressor, the aluminum substrate 01 is directly set to a curved surface.

[0045] In this embodiment of the invention, the copper foil layer 03 is etched to form a circuit, thus creating a circuit wiring layer.

[0046] In this embodiment of the invention, the lead frame 4 is made of copper alloy. Specifically, the material is C194(-1 / 2H) (chemical composition: Cu(≧97.0)Fe:2.4P:0.03Zn:0.12) or KFC(-1 / 2H) (chemical composition: Cu(≧99.6)Fe:0.1(0.05~0.15)P:0.03(0.025~0.04)). The 0.5mm copper plate is stamped to form the required shape by machining, and then the surface is first nickel plated with a thickness of 0.1-0.5um, and then tin plated with a thickness of 2-5um.

[0047] In this embodiment of the invention, the circuit components include surface-mount capacitors 8 that serve as filters, couplers, and bootstraps; surface-mount resistors 7 that limit switching speed; and components 10 that form the internal circuit chip.

[0048] In this embodiment of the invention, the upper electromagnet 102 and the lower electromagnet 101 are attached between the molding compound 3 and the lead frame movable space 103.

[0049] In this embodiment of the invention, the mold body includes an upper mold 1 and a lower mold 5. The upper mold 1 is recessed on one side near the pin frame 4 to form an upper groove, and the lower mold 5 is recessed on the other side near the pin frame 4 to form a lower groove. The upper mold 1 and the lower mold 5 are fitted together so that the upper groove and the lower groove are correspondingly arranged to form the lead frame movable space 103.

[0050] Specifically, in the prior art, after semiconductor circuit packaging, the three tolerances of aluminum substrate 6 (±10%), lead frame 4 welding tolerance and packaging mold tolerance are superimposed, causing the surface of aluminum substrate 6 and packaging mold to not fit properly, resulting in three situations: gap contact, over-contact, and normal contact.

[0051] Among them, gap contact: such as Figure 2 As shown, when the assembly tolerance between the lead frame 4 and the aluminum substrate 6 is less than the cavity depth of the lower mold 5, there will be a gap between the aluminum substrate 6 and the lower mold 5. The molding compound 3 will soften at the 180°C encapsulation mold temperature. The molding compound 3 is injected into the cavity of the lower mold 5 by the injection pressure of the equipment. Under the injection pressure, the gap between the substrate 6 and the lower mold 5 will also be filled into the gap, resulting in overflow. The solution to overflow is to eliminate the gap between the aluminum substrate 6 and the lower mold 5. This is achieved by adding movable pins 2 in the encapsulation mold to apply pressure to the aluminum substrate 6, making the aluminum substrate 6 and the lower mold 5 fit tightly together. Under the external force of the movable pins 2, a downward force will be generated between the lead frame 4 and the aluminum substrate 6. Crack 06 will appear at the weakest point of the connection between the two. The insulating layer 02 becomes very fragile at high temperatures (encapsulation mold temperature 180°C). Once an external force is generated in the middle, crack 06 will be generated, and crack 06 appears at the end of the lead frame 4.

[0052] Over-contact: such as Figure 3 As shown, when the assembly tolerance between the lead frame 4 and the aluminum substrate 6 is greater than the cavity depth of the lower mold 5, the lead frame 4 will be higher than the mold closing surface of the packaging mold. When the packaging mold closes, there will be a squeezing force between the lead frame 4 and the aluminum substrate 6. Under this squeezing force, the insulating layer 02 will also develop cracks 06, and the cracks 06 will appear at the tail of the lead frame 4.

[0053] Normal contact: such as Figure 4 As shown, when the assembly tolerance of the lead frame 4 and the aluminum substrate 6 is equal to the cavity depth of the lower mold 5, the aluminum substrate 6 and the lower mold 5 fit together tightly. During the mold closing process, no force is generated between the lead frame 4 and the aluminum substrate 6. In this case, neither glue overflow nor delamination will occur. However, in the actual production process, there will always be some tolerance.

[0054] In embodiments of the present invention, such as Figure 1As shown, when the upper electromagnet 102 and the lower magnet 101 are energized, a magnetic attraction phenomenon occurs between them, pressing the lead frame 4 tightly. The upper mold 1 and the lower mold 5 will close, preventing the molding compound 3 from flowing into the lead frame's movable space 103, thereby preventing glue overflow. The upper electromagnet 102 and the lower electromagnet 101 work together to prevent glue overflow from occurring in the lead frame's movable space 103. The lead frame's movable space 103 is used to accommodate the tolerances of the aluminum substrate 6, the lead frame 4, the packaging mold itself, and the combined fitting tolerances, preventing stress from occurring at the connection between the lead frame 4 and the aluminum substrate 6. Figure 2 As shown, after injection molding, the upper electromagnet 102 and the lower electromagnet 101 will be de-energized, the magnetic attraction will disappear, and the upper electromagnet 102 and the lower electromagnet 101 will open together with the upper mold 1 and the lower mold 5. In this way, the problem of cracking of the insulation layer 02 caused by stress and the problem of glue overflow of the aluminum substrate 6 and the lead frame 4 are effectively solved.

[0055] In this embodiment of the invention, the lead frame 4 and the aluminum substrate 6 are electrically connected by soldering with lead solder 05. Specifically, the lead solder 05 is a uniform mixture of alloy powder and solder resist in a certain proportion, and the lead frame 4 and the aluminum substrate 6 are electrically connected by soldering with high temperature reflow.

[0056] (Example 2)

[0057] like Figure 7 As shown, Figure 7 This is a flowchart of a semiconductor circuit manufacturing method provided by the present invention. The present invention also provides a semiconductor circuit manufacturing method based on the electromagnetic packaging mold of the semiconductor circuit in Embodiment 1 above. The manufacturing method includes the following steps:

[0058] S1. The metal substrate 6 is placed in a special carrier by automated equipment or manual labor.

[0059] Specifically, the specially designed carrier can be any one of the following materials that can withstand temperatures above 200°C: aluminum, synthetic stone, ceramics, or polyphenylene sulfide.

[0060] S2. The semiconductor inverter circuit chip is mounted onto the component mounting position reserved in the copper foil layer 03 of the metal substrate 6 by brushing solder paste or applying silver glue through an automatic die bonding device.

[0061] S3. High-voltage power devices are mounted onto silver-plated copper heat sinks using a soft solder die bonder to form semi-finished components.

[0062] S4. Using an automated surface mount technology (SMT) device to reduce resistance and capacitance, the semi-finished components are mounted onto the component mounting positions.

[0063] S5. The lead frame is placed on the corresponding welding position of the metal substrate 6 by a robot or manually, the metal substrate 6 including the special carrier is passed through the reflow oven, and all the circuit components are welded to the corresponding mounting positions.

[0064] S6. The soldering quality of the circuit components is inspected by visual inspection AOI equipment, and flux and aluminum shavings remaining on the metal substrate 6 are removed by spraying and ultrasonication.

[0065] S7. The circuit components and the circuit wiring layer are electrically connected through the bonding metal wire 9.

[0066] S8. The circuit of the metal substrate 6 is encapsulated in a specific mold using a packaging device. Specifically, during injection molding, the upper electromagnet 102 and the lower magnet 101 are energized, and a magnetic attraction phenomenon will occur between them to press the lead frame 4 tightly. After injection molding is completed, the upper electromagnet 102 and the lower magnet 101 are de-energized, the magnetic attraction phenomenon disappears, and the upper electromagnet 102 and the lower magnet 101 are opened together with the mold opening. Then, they are marked by laser marking.

[0067] S9. Post-curing stress relief treatment is carried out in a high-temperature oven;

[0068] S10. The connecting ribs and dummy pins of the pins are cut off and shaped into the required shape using a rib cutting and forming equipment. Finally, electrical parameter testing is performed to form the final qualified product.

[0069] Compared to existing technologies, this invention absorbs the combined tolerances of the aluminum substrate (±10%), lead frame welding tolerances, and mold tolerances through the lead frame's movable space. This ensures no stress is generated between the substrate and the lead frame. Simultaneously, the energization of the upper and lower electromagnets clamps the lead frame, preventing molding compound from flowing into the lead frame's movable space and causing the risk of lead frame overflow. These methods solve both the problem of insulation layer cracking caused by stress and the problem of molded compound overflow between the substrate and the lead frame, thus improving the reliability of semiconductor circuits.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any alterations, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. An electromagnetic packaging mold for a semiconductor circuit, the semiconductor circuit comprising a metal substrate; a plurality of circuit components disposed at predetermined positions on the metal substrate; bonding metal wires for electrically connecting the plurality of circuit components; a lead frame for connecting to the metal substrate and extending outward as input / output; a molding compound covering the metal substrate, the molding compound at least sealing the connection portion between the lead frame and the metal substrate, and at least a portion of the outwardly extending lead frame being exposed without being sealed; movable pins embedded in the molding compound and pressed against the metal substrate; characterized in that, The packaging mold includes a mold body, and the mold body provides a lead frame movement space for the exposed portion of the lead frame; an upper electromagnet and a lower electromagnet are respectively attached to opposite sides of the lead frame movement space, and the upper electromagnet and the lower electromagnet are used to clamp the lead frame when the mold is closed; the metal substrate includes a metal substrate, an insulating layer, a copper foil layer and a protective layer, the insulating layer is attached to one side of the metal substrate, the copper foil layer is pressed onto the side of the insulating layer away from the metal substrate, and the protective layer is attached to the side of the copper foil layer away from the insulating layer; The copper foil layer is formed into a circuit wiring layer by etching.

2. The electromagnetic packaging mold for a semiconductor circuit according to Claim 1, wherein The metal substrate has a curved surface.

3. The electromagnetic package mold for a semiconductor circuit according to Claim 1, wherein The lead frame is made of copper alloy.

4. The electromagnetic package mold for a semiconductor circuit according to Claim 1, wherein The circuit components include surface mount capacitors, surface mount resistors, and other components, which are respectively mounted on the metal substrate.

5. The electromagnetic package mold for a semiconductor circuit according to Claim 1, wherein The upper electromagnet and the lower electromagnet are attached between the molding compound and the movable space of the lead frame.

6. The electromagnetic package mold for a semiconductor circuit according to claim 1, wherein The lead frame and the metal substrate are electrically connected by lead soldering.

7. The electromagnetic package mold for a semiconductor circuit according to claim 1, wherein The mold body includes an upper mold and a lower mold. The upper mold has an upper groove formed by a recess on one side near the lead frame, and the lower mold has a lower groove formed by a recess on the other side near the lead frame. The upper mold and the lower mold are fitted together so that the upper groove and the lower groove are correspondingly arranged to form the movable space of the lead frame.

8. A method for manufacturing a semiconductor circuit, characterized in that, The method includes an electromagnetic packaging mold for a semiconductor circuit according to any one of claims 1-7, and comprises the following steps: S1. The metal substrate is placed on the carrier by automated equipment or manual labor. S2. The semiconductor inverter circuit chip is mounted onto the component mounting position reserved in the copper foil layer of the metal substrate by applying solder paste or applying silver glue through an automatic die bonding device. S3. High-voltage power devices are mounted onto silver-plated copper heat sinks using a soft solder die bonder to form semi-finished components. S4. Using an automated surface mount technology (SMT) device to reduce resistance and capacitance, the semi-finished components are mounted onto the component mounting positions. S5. The lead frame is placed on the corresponding welding position of the metal substrate by means of a robot or manual labor. The metal substrate, including the carrier, is passed through a reflow oven and all the circuit components are welded to the corresponding mounting positions. S6. The soldering quality of the circuit components is inspected by visual inspection AOI equipment, and flux and aluminum shavings remaining on the metal substrate are removed by spraying and ultrasonication. S7. The circuit components and the circuit wiring layer are electrically connected through the bonding metal wire; S8. The metal substrate is encapsulated in a mold using a packaging device, and then marked with a laser. S9. Post-curing stress relief treatment is carried out in a high-temperature oven; S10. The connecting ribs and dummy pins of the pins are cut off and shaped into the required shape using a rib cutting and forming equipment. Finally, electrical parameter testing is performed to form the final qualified product.

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