Packaging method of duplex SAW filter and filter

Abstract

The invention discloses a packaging method of a duplex SAW filter and the filter, the filter comprises a substrate, substrate bottom pins, a substrate PAD, gold balls, a wafer of an RX chip, a wafer of a TX chip and an epoxy resin film, the bottoms of the wafer of the RX chip and the wafer of the TX chip are fixedly provided with the gold balls, the bottoms of the gold balls are arranged on the substrate PAD, the bottom of the substrate PAD is arranged on the substrate, and the epoxy resin film is arranged on the substrate PAD. Substrate bottom pins are installed at the bottom of the substrate, epoxy resin films are packaged above the wafer of the RX chip and the wafer of the TX chip, and the epoxy resin films wrap the back faces and the four side faces of the wafer of the RX chip and the wafer of the TX chip. The duplex SAW is divided into the RX chip and the TX chip, and the RX chip and the TX chip are packaged together in parallel, so that the phenomenon that an open circuit often occurs in the duplex SAW packaging industry is solved, and the complete electrical performance and the overall packaging size of the duplex SAW are kept unchanged.

Description

Technical Field

[0001] The invention discloses a filter, in particular to a packaging method of a duplex SAW filter and the filter, and relates to the technical field of semiconductor chip packaging. Background Art

[0002] With the improvement of packaging technology and the development of miniaturization, lightweight and high-density electronic equipment, SAW filter is the abbreviation of surface acoustic wave filter. Surface acoustic wave devices are widely used in the field of mobile terminals due to their advantages such as miniaturization and low insertion loss. It is particularly important to solve the open circuit phenomenon that often occurs in the duplex SAW packaging industry.

[0003] As a bidirectional three-port device, the duplexer is mainly composed of two bandpass filters. The common end of the two filters is the antenna end, and the other two ports correspond to the transmitting end and the receiving end respectively. Due to the integration of the RX and TX parts, the chip size is much larger than the single-ended (RX or TX) SAW. When using conventional packaging technology, factors such as uneven flip-chip force, poor ultrasonic transmission capability, and limited packaging equipment capabilities lead to poor bonding effects, and factors such as differences in laminating methods and large overall chip size lead to open circuits in the final packaged product due to stress. Summary of the invention

[0004] In view of the problem that the duplexer in the prior art mentioned above is prone to open circuit in the packaged finished product due to stress, a packaging method and filter for a duplex SAW filter is proposed, which splits the duplex SAW into an RX chip and a TX chip, and packages them together in parallel, thereby solving the open circuit problem that often occurs in the duplex SAW packaging industry, while maintaining the complete electrical performance and overall packaging size of the duplex SAW.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a duplex SAW filter, the filter comprises a substrate, pins at the bottom of the substrate, a substrate PAD, a gold ball, a wafer of an RX chip, a wafer of a TX chip and an epoxy resin film, the bottom of the wafer of the RX chip and the wafer of the TX chip are fixedly mounted with a gold ball, the bottom of the gold ball is mounted on the substrate PAD, the bottom of the substrate PAD is mounted on the substrate, the bottom of the substrate is mounted with pins at the bottom of the substrate, the wafer of the RX chip and the wafer of the TX chip are packaged with an epoxy resin film above them, and the epoxy resin film wraps the back and four side surfaces of the wafer of the RX chip and the wafer of the TX chip.

[0006] A packaging method for a duplex SAW filter, the method comprising the following steps: Step S1, wafer ball planting, planting gold balls on the wafer of the RX chip and the wafer of the TX chip; Step S2: wafer dicing to divide the wafer into a single RX chip or TX chip area; Step S3, flip-chip bonding, flip-chip bonding the diced wafer; Step S4, applying an epoxy resin film, and laminating the epoxy resin film to one side of the substrate on which the chip is flipped by a film laminating device under high temperature, pressure and vacuum conditions; Step S5, using an oven to bake the substrate with the epoxy resin film at 150° C. for 15 to 30 minutes; Step S6, using a laser device to print the required silk screen on the back of the chip wrapped with the epoxy resin film; Step S7: cutting the substrate: cutting the substrate; Step S8, product aging treatment; Step S9: sort and test the products according to product indicators and package them into final products.

[0007] The technical solution adopted by the present invention to solve the technical problem further includes: Two gold balls are installed under the wafer of the RX chip, and a substrate PAD is installed under each gold ball.

[0008] Three gold balls are installed under the wafer of the TX chip, and a substrate PAD is installed under each gold ball.

[0009] The base plate is provided with three pins at the bottom.

[0010] The step S1 includes the following sub-steps: Step S1-1, using pure water to clean the wafer to remove dirt and large particles of pollutants on the wafer surface; Step S1-2, using argon and / or hydrogen as a gas source to perform plasma cleaning on the wafer to remove surface contaminants; Step S1-3: Use a gold ball implanting device and gold wire to implant gold balls on all pads of each chip on the surface of the wafer that need to be connected.

[0011] The step S2 includes the following sub-steps: Step S2-1, evenly coating the surface of the wafer with photoresist; Step S2-2, attaching a UV film to the back of the wafer; Step S2-3, using a device to slice the wafer into a single RX chip or TX chip of a corresponding chip design size; Step S2-4, removing the photoresist on the surface of the wafer by a degumming cleaning method; Step S2-5, dissolve the UV by using a dissolver.

[0012] The step S3 includes the following sub-steps: Step S3-1, using argon as a gas source to perform plasma cleaning on the wafer to remove surface contaminants; Step S3-2, using argon and / or oxygen as a gas source to perform plasma cleaning on the substrate to remove surface contaminants; Step S3-3: Use the flip-chip device to first suck up the chips on the wafer that implements the RX function one by one, flip them over, and transfer them to the welding nozzle required for flip-chip.

[0013] The step S7 includes the following sub-steps: Step S7-1, attaching the side of the substrate with the epoxy resin film to the UV film; Step S7-2, cutting the substrate into a size corresponding to the product by a cutting device; Step S7-3: After UV debonding, the chip is peeled off into monomers.

[0014] The step S8 includes the following sub-steps: Step S8-1, storing the product in a high temperature environment and a low temperature environment for 10 to 20 times in a cycle, when specifically implemented; Step S8-2: Store the product in a high temperature environment for 8 hours to 10 hours.

[0015] The beneficial effect of the present invention is that the present invention splits the duplex SAW into an RX chip and a TX chip, and packages them together in parallel, thereby solving the open circuit problem that often occurs in the duplex SAW packaging industry, while maintaining the complete electrical performance and overall packaging size of the duplex SAW.

[0016] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the RX Chip Wafer and the TX Chip Wafer after ball implantation of the present invention.

[0018] Figure 2 It is a schematic diagram of the structure of the RX Chip Wafer and the TX Chip Wafer after dicing of the present invention.

[0019] Figure 3 It is a schematic diagram of the structure of the flip-chip RX Chip Wafer and the flip-chip TX Chip Wafer of the present invention.

[0020] Figure 4 It is a schematic diagram of the structure after coating of the present invention.

[0021] Figure 5 It is a schematic diagram of the structure of the substrate after cutting of the present invention.

[0022] Figure 6 It is a structural schematic diagram of the final product of the present invention.

[0023] In the figure, 1-gold ball, 2-wafer of RX chip, 3-wafer of TX chip, 4-UV film, 5-substrate PAD, 6-substrate, 7-pins at the bottom of substrate, 8-epoxy resin film, 9-silk screen layer. DETAILED DESCRIPTION

[0024] This embodiment is a preferred implementation mode of the present invention. Other embodiments whose principles and basic structures are the same or similar to those of this embodiment are within the protection scope of the present invention.

[0025] Please refer to the attached Figure 1 To Attachment Figure 6 The present invention mainly protects a duplex SAW filter, which packages two chips together, mainly including a substrate 6, a substrate bottom pin 7, a substrate PAD5, a gold ball 1, a wafer 2 of an RX chip, a wafer 3 of a TX chip and an epoxy resin film 8. The bottom of the wafer 2 of the RX chip and the wafer 3 of the TX chip are fixedly mounted with a gold ball 1, the bottom of the gold ball 1 is mounted on the substrate PAD5, and the bottom of the substrate PAD5 is mounted on the substrate 6, that is, the wafer 2 of the RX chip and the wafer 3 of the TX chip are respectively mounted on the substrate 6 through the gold ball 1 and the substrate PAD5, and the bottom of the substrate 6 is mounted with a substrate bottom pin 7. The epoxy resin film 8 is packaged above the wafer 2 of the RX chip and the wafer 3 of the TX chip, and the epoxy resin film 8 wraps the back and four side surfaces of the wafer 2 of the RX chip and the wafer 3 of the TX chip and is bonded to the substrate 6 to achieve a sealing effect on the chip.

[0026] In this embodiment, two gold balls 1 are installed under the wafer 2 of the RX chip, and a substrate PAD5 is installed under each gold ball 1.

[0027] In this embodiment, three gold balls 1 are installed under the wafer 3 of the TX chip, and a substrate PAD5 is installed under each gold ball 1 .

[0028] In this embodiment, three pins 7 are provided at the bottom of the substrate, and the pins 7 at the bottom of the substrate are soldering pads. During specific implementation, the number, size and position of the soldering pads are designed according to actual needs.

[0029] The present invention designs independent RX functional areas and TX functional areas of a duplex SAW filter chip according to product electrical performance indicators. The RX functional area and the TX functional area are used as two small chips. The small chips are provided with pads. The number, size and position of the pads are designed according to actual needs.

[0030] The present invention also protects a packaging method for a duplex SAW filter, the method comprising the following steps: Step S1, wafer ball implantation, that is, implanting gold balls 1 on wafer 2 of the RX chip and wafer 3 of the TX chip, which specifically includes the following sub-steps: Step S1-1, using pure water to clean the wafers (including wafer 2 of the RX chip and wafer 3 of the TX chip) to remove dirt on the wafer surface, especially large particles of pollutants; Step S1-2, using argon and / or hydrogen as a gas source to perform plasma cleaning on the wafer to remove surface contaminants; Step S1-3: Use a gold ball implanting device and gold wire to implant gold balls on all pads of each chip on the surface of the wafer that need to be connected.

[0031] Step S2, wafer dicing, dividing a single RX chip or TX chip area on the wafer, which specifically includes the following sub-steps: Step S2-1, evenly apply photoresist on the surface of the wafer to protect it; Step S2-2, attaching a UV film 4 to the back of the wafer; Step S2-3, using a device to slice the wafer into a single RX chip or TX chip of a corresponding chip design size; Step S2-4, removing the photoresist on the surface of the wafer by cleaning; Step S2-5, dissolve the UV by using a dissolver.

[0032] Step S3, flip-chip bonding, flip the diced wafer, and the spacing between the RX chip and the TX chip packaged in parallel is determined according to the size of the RX chip, TX chip, the alignment accuracy of the equipment, and the thickness of the resin film that needs to be retained around the duplex SAW, while keeping the size of the finished product with complete duplex function unchanged after being placed in parallel. The RX chip and the TX chip can be designed on the same wafer or separately on different wafers according to actual requirements. During flip-chip bonding, the RX chip can be flipped first and then the TX chip, or the two chips can be flipped alternately at the same time. It specifically includes the following sub-steps: Step S3-1, using argon as a gas source to perform plasma cleaning on the wafer to remove surface contaminants; Step S3-2, using argon and / or oxygen as a gas source to perform plasma cleaning on the 1814-size substrate to remove surface contaminants; Step S3-3, first use the flip-chip equipment to suck up the chips on the wafer that implements the RX function one by one, then flip them over, and transfer them to the welding nozzle required for flip-chip. At this time, the ball bumps on the chip face downward and the back of the chip is sucked by the welding nozzle. The flip-chip equipment aligns the chip with the corresponding position on the substrate 6 and contacts the substrate 6. While applying a pressure of 5N~10N, 0.05W~0.15W ultrasonic power and 190℃~230℃ temperature, the ball bumps and the connection points on the substrate 6 are bonded in the form of solid solution, and at this time there is still a gap of 10-17um between the substrate 6 and the chip.

[0033] After the chips with RX function are flipped upside down on the substrate 6, the chips on the wafer that realize TX function are flipped upside down in parallel next to the RX chips in the same way.

[0034] Step S4, applying epoxy resin film 8, by laminating the epoxy resin film to one side of substrate 6 with the flip-mounted chip under high temperature (usually between 150°C and 200°C), pressure (usually between 10MPa and 50MPa) and vacuum conditions through film laminating equipment, so that the chip is fully wrapped by epoxy resin film 8 and epoxy resin film 8 is bonded to substrate 6.

[0035] Step S5, using an oven to bake the substrate 6 with the epoxy resin film 8 at 150°C, so that the epoxy resin film 8 is fully bonded to the substrate 6 to achieve a sealing effect on the chip.

[0036] Step S6: Use a laser device to print the silk-screen layer 9 required for the product on the back of the chip wrapped with the epoxy resin film 8.

[0037] Step S7, substrate cutting, cutting the substrate 6, which specifically includes the following sub-steps: Step S7-1, attaching the side of the substrate 6 with the epoxy resin film 8 to the UV film 4; Step S7-2, cutting the substrate 6 into a size corresponding to the product by a cutting device; Step S7-3: After UV debonding, the chip is peeled off into monomers.

[0038] Step S8, product aging treatment. In this embodiment, a sealing test can be added before step S8, which specifically includes the following sub-steps: Step S8-1, the product is stored in a high temperature environment (usually between 150°C and 300°C) and a low temperature environment (usually between -50°C and 0°C) for 10 to 20 times. In specific implementation, the number of high and low temperature cycles and the high temperature storage time can be adjusted according to actual needs; Step S8-2: Store the product in a high temperature environment (usually between 150°C and 300°C) for 8H to 10H.

[0039] Step S9: sort and test the products according to product indicators and package them into final products. In this embodiment, a sealing test can be added before step S9.

[0040] The present invention splits the duplex SAW into an RX chip and a TX chip, and packages them together in parallel, thereby solving the open circuit problem that often occurs in the duplex SAW packaging industry, while maintaining the complete electrical performance and overall packaging size of the duplex SAW unchanged.

Claims

1. A duplex SAW filter, characterized in that: The filter comprises a substrate (6), a substrate bottom pin (7), a substrate PAD (5), a gold ball (1), an RX chip wafer (2), a TX chip wafer (3) and an epoxy resin film (8); the gold ball (1) is fixedly mounted on the bottom of the RX chip wafer (2) and the TX chip wafer (3); the bottom of the gold ball (1) is mounted on the substrate PAD (5); the bottom of the substrate PAD (5) is mounted on the substrate (6); the bottom of the substrate (6) is mounted with a substrate bottom pin (7); the epoxy resin film (8) is encapsulated above the RX chip wafer (2) and the TX chip wafer (3); the epoxy resin film (8) wraps the back and four side surfaces of the RX chip wafer (2) and the TX chip wafer (3).

2. The duplex SAW filter according to claim 1, characterized in that: Two gold balls (1) are installed below the wafer (2) of the RX chip, and a substrate PAD (5) is installed below each gold ball (1).

3. The duplex SAW filter according to claim 1, characterized in that: Three gold balls (1) are installed below the wafer (3) of the TX chip, and a substrate PAD (5) is installed below each gold ball (1).

4. The duplex SAW filter according to claim 1, characterized in that: There are three pins (7) at the bottom of the substrate.

5. A packaging method for a duplex SAW filter, characterized in that: The method comprises the following steps: Step S1, wafer ball planting, planting gold balls (1) on the wafer (2) of the RX chip and the wafer (3) of the TX chip; Step S2: wafer dicing to divide the wafer into a single RX chip or TX chip area; Step S3, flip-chip bonding, flip-chip bonding the diced wafer; Step S4, applying an epoxy resin film (8), by laminating the epoxy resin film onto one side of the substrate (6) on which the chip is flipped, under conditions of high temperature, pressure and vacuum, using a film laminating device; Step S5, using an oven to bake the substrate (6) with the epoxy resin film (8) at 150° C. for 15 to 30 minutes; Step S6, using a laser device to print the silk screen required by the product on the back of the chip wrapped with the epoxy resin film (8); Step S7, substrate cutting, cutting the substrate (6); Step S8, product aging treatment; Step S9: sort and test the products according to product indicators and package them into final products.

6. The packaging method of the duplex SAW filter according to claim 5, characterized in that: The step S1 includes the following sub-steps: Step S1-1, using pure water to clean the wafer to remove dirt and large particles of pollutants on the wafer surface; Step S1-2, using argon and / or hydrogen as a gas source to perform plasma cleaning on the wafer to remove surface contaminants; Step S1-3: Use a gold ball implanting device and gold wire to implant gold balls on all pads of each chip on the surface of the wafer that need to be connected.

7. The packaging method of the duplex SAW filter according to claim 5, characterized in that: The step S2 includes the following sub-steps: Step S2-1, evenly coating the surface of the wafer with photoresist; Step S2-2, attaching a UV film (4) to the back of the wafer; Step S2-3, using a device to slice the wafer into a single RX chip or TX chip of a corresponding chip design size; Step S2-4, removing the photoresist on the surface of the wafer by a degumming cleaning method; Step S2-5, dissolve the UV by using a dissolver.

8. The packaging method of the duplex SAW filter according to claim 5, characterized in that: The step S3 includes the following sub-steps: Step S3-1, using argon as a gas source to perform plasma cleaning on the wafer to remove surface contaminants; Step S3-2, using argon and / or oxygen as a gas source to perform plasma cleaning on the substrate to remove surface contaminants; Step S3-3: Use the flip-chip device to first suck up the chips on the wafer that implements the RX function one by one, flip them over, and transfer them to the welding nozzle required for flip-chip.

9. The packaging method of the duplex SAW filter according to claim 5, characterized in that: The step S7 includes the following sub-steps: Step S7-1, attaching the side of the substrate (6) having the epoxy resin film (8) to the UV film (4); Step S7-2, cutting the substrate (6) into a size corresponding to the product by a cutting device; Step S7-3: After UV debonding, the chip is peeled off into monomers.

10. The packaging method of the duplex SAW filter according to claim 5, characterized in that: The step S8 includes the following sub-steps: Step S8-1, storing the product in a high temperature environment and a low temperature environment for 10 to 20 times in a cycle, when specifically implemented; Step S8-2: Store the product in a high temperature environment for 8 hours to 10 hours.

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