Processing technology of multi-chip special-shaped plastic packaging MEMS (Micro Electro Mechanical System) product

Abstract

The invention discloses a processing technology of a multi-chip special-shaped plastic packaging MEMS (Micro Electro Mechanical System) product. The processing technology comprises the following steps of performing baking and solder paste printing on a whole substrate; mounting the components and the plurality of ASIC chips on the whole substrate respectively; performing plastic packaging on the whole substrate, and forming at least two accommodating cavities on the outer side of each ASIC chip through a packaging body in the packaging process; the plastic package substrate is pre-cut according to a single MEMS product, and the pre-cutting depth is smaller than the thickness of the plastic package substrate; for the pre-cut plastic package substrate, dispensing glue into a plurality of accommodating cavities on the plastic package substrate and mounting MEMS chips on the plastic package substrate; and the plastic package substrate is cut again according to a single MEMS product, and the single MEMS product is obtained. According to the invention, the problem of warping of the plastic package body is solved before the MEMS chip is subjected to dispensing and mounting, so that dispensing and chip mounting can be directly carried out without measuring the height of each product position.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS product processing, and in particular to a processing technology for a multi-chip special-shaped plastic-sealed MEMS product. Background Art

[0002] The current process typically involves measuring the height of each sealed product before performing subsequent dispensing and die placement operations to ensure consistent placement height and adhesive coverage around the die. However, these two steps can result in a 60% reduction in processing speed, and the equipment required for these two processes is expensive, leading to high processing costs. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a processing technology for multi-chip special-shaped plastic-sealed MEMS products, which realizes high-quality and high-speed operation, ensures the quality and yield of large-scale mass production and reduces processing costs.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: a processing technology for a multi-chip special-shaped plastic-encapsulated MEMS product, wherein a single MEMS product includes: a product substrate, a plurality of components arranged on the product substrate and electrically connected to the product substrate, and a package body covering the product substrate and the components, and further includes an ASIC chip and at least two MEMS chips, wherein the ASIC chip electrically connected to the product substrate is located in the package body, and each MEMS chip is arranged in a receiving cavity surrounded by the package body and electrically connected to the product substrate. The processing technology includes the following steps: S1. Bake the entire substrate and print solder paste; S2, mounting components and multiple ASIC chips onto the whole board substrate printed with solder paste obtained in S1; S3. Plastic encapsulate the entire substrate with components and multiple ASIC chips mounted thereon obtained in S2, and during the encapsulation process, form at least two accommodating cavities outside each ASIC chip through the encapsulation body; S4. Pre-cutting the plastic substrate encapsulating the multiple ASIC chips obtained in S3 into individual MEMS products, with the depth of the pre-cutting being less than the thickness of the plastic substrate, so that a cutting gap is formed between the package of each MEMS product and the package of an adjacent MEMS product, and each MEMS product is still connected to its adjacent MEMS product; S5. For the plastic-encapsulated substrate pre-cut in S4, glue is dispensed into the multiple accommodating cavities thereon and the MEMS chips are mounted thereon; S6. Re-cut the plastic-encapsulated substrate obtained through S5 processing according to individual MEMS products to obtain individual MEMS products.

[0005] The further improved scheme in the above technical scheme is as follows: 1. In the above scheme, before step S5, the method further includes: using an adsorption fixture to adsorb and position the plastic-encapsulated substrate pre-cut in S4, wherein the carrier plate of the adsorption fixture is provided with a plurality of adsorption hole groups corresponding to the individual MEMS products on the plastic-encapsulated substrate.

[0006] 2. In the above solution, step S2 further comprises: S21, using a placement machine to mount components onto the entire substrate printed with solder paste; S22, reflow soldering and perform optical automatic inspection after soldering; S23, cleaning the flux and then baking it; S24. Use glue to mount the ASIC chip on the entire board substrate and perform gold wire welding.

[0007] 3. In the above solution, before step S6, the method further includes: Bake and solidify the plastic-sealed substrate with the MEMS chip mounted on it; Conduct leakage tests on individual MEMS products on plastic-sealed substrates; After plasma cleaning, gold wire welding is used to connect the MEMS chip to the plastic package substrate printed with solder paste; Bottom filling, curing, refilling, vacuum degassing, curing; Perform bubble test after rapid pressure relief; Electrical testing, laser marking.

[0008] 4. In the above solution, step S6 further comprises: S61, laminating the plastic packaging body surface and the substrate surface of the plastic packaging substrate obtained by the step S6; S62, cutting the plastic package substrate from the plastic package surface; S63, performing UV debonding on the plastic package surface and the substrate surface respectively; S64, removing the adhesive film on the substrate surface; S65, transferring the single MEMS product with the adhesive film on the substrate removed to a loading tray; S66. Remove the film on the surface of the plastic package.

[0009] 5. In the above solution, step S1 further comprises: performing optical inspection on the entire printed substrate.

[0010] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: The processing technology of the multi-chip special-shaped plastic-encapsulated MEMS product of the present invention solves the problem of plastic package warping before gluing and mounting the MEMS chip, so that gluing and chip mounting can be directly performed without measuring the height of each product position. It can also eliminate the risk of sudden deformation of the product after height measurement and before mounting in the existing process, thereby achieving high-quality and high-speed operation, ensuring the quality and yield of large-scale mass production and reducing processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Attachment Figure 1 is a schematic diagram of a whole substrate obtained through processing in step S1; Attachment Figure 2 is a schematic diagram of a whole substrate obtained after processing in step S2; Attachment Figure 3 Schematic diagram of the plastic-encapsulated substrate obtained after processing in step S3; Attachment Figure 4 Schematic diagram of the pre-cut and plastic-sealed substrate obtained through step S4; Attachment Figure 5 is a schematic diagram of the plastic-encapsulated substrate obtained after processing in step S5; Attachment Figure 6 Schematic diagram of the structure of a single MEMS product obtained by processing; Attachment Figure 7 Schematic diagram of the structural cross-section of a single MEMS product obtained through processing; Attachment Figure 8 This is a schematic diagram of the process of Example 2 of the present invention; Attachment Figure 9 Schematic diagram of the adsorption fixture in the present invention; Attachment Figure 10 This is the glue height measurement value after the MEMS chip is mounted in the product obtained by the present invention.

[0012] In the above figures: 1. Product substrate; 2. Components; 3. Package; 4. ASIC chip; 5. MEMS chip; 6. Accommodation cavity. DETAILED DESCRIPTION

[0013] The present invention can be further understood through the specific embodiments given below, but they are not intended to limit the present invention.

[0014] Example 1: A processing technology for a multi-chip, special-shaped, plastic-encapsulated MEMS product. A single MEMS product includes: a product substrate 1, a plurality of components 2 disposed on the product substrate 1 and electrically connected to the product substrate 1, and a package body 3 covering the outside of the product substrate 1 and the components 2. The product also includes an ASIC chip 4 and at least two MEMS chips 5. The ASIC chip 4 electrically connected to the product substrate 1 is located within the package body 3. Each MEMS chip 5 is disposed within a receiving cavity 6 surrounded by the package body 3 and electrically connected to the product substrate 1. The processing technology includes the following steps: S1. Bake the entire board substrate, print solder paste, and perform optical inspection on the printed entire board substrate; S2, mounting components and multiple ASIC chips onto the whole board substrate printed with solder paste obtained in S1; S3. Plastic encapsulate the entire substrate with components and multiple ASIC chips mounted thereon obtained in S2, and during the encapsulation process, form at least two accommodating cavities outside each ASIC chip through the encapsulation body; S4. Pre-cutting the plastic substrate encapsulating the multiple ASIC chips obtained in S3 into individual MEMS products, with the depth of the pre-cutting being less than the thickness of the plastic substrate, so that a cutting gap is formed between the package of each MEMS product and the package of an adjacent MEMS product, and each MEMS product is still connected to its adjacent MEMS product; S5. For the plastic-encapsulated substrate pre-cut in S4, glue is dispensed into the multiple accommodating cavities thereon and the MEMS chips are mounted thereon; S6. Re-cut the plastic-encapsulated substrate obtained through S5 processing according to individual MEMS products to obtain individual MEMS products.

[0015] Example 2: A processing technology for a multi-chip special-shaped plastic-encapsulated MEMS product, comprising the following steps: S1. Bake the entire substrate and print solder paste; S2: Mount components (capacitors, inductors, etc.) and multiple ASIC chips (integrated circuit chips) onto the entire substrate printed with solder paste obtained in S1. Specifically: S21, using a placement machine to mount components onto the entire substrate printed with solder paste; S22, reflow soldering and perform optical automatic inspection after soldering; S23, cleaning the flux and then baking it; S24, using glue to mount the ASIC chip on the entire board substrate and perform gold wire bonding; S3. Plastic encapsulate the entire substrate with components and multiple ASIC chips mounted thereon obtained in S2, and during the encapsulation process, form at least two accommodating cavities outside each ASIC chip through the encapsulation body; S4. Pre-cutting the plastic substrate encapsulating the multiple ASIC chips obtained in S3 into individual MEMS products, with the depth of the pre-cutting being less than the thickness of the plastic substrate, so that a cutting gap is formed between the package of each MEMS product and the package of an adjacent MEMS product, and each MEMS product is still connected to its adjacent MEMS product; Adopt an adsorption fixture to adsorb and position the plastic-encapsulated substrate pre-cut by S4. The carrier plate of the adsorption fixture is provided with a plurality of adsorption hole groups corresponding to the single MEMS products on the plastic-encapsulated substrate. S5. For the plastic-encapsulated substrate pre-cut in S4, glue is dispensed into the multiple accommodating cavities thereon and the MEMS chips are mounted thereon; Bake and solidify the plastic-sealed substrate with the MEMS chip mounted on it; Conduct leakage tests on individual MEMS products on plastic-sealed substrates; After plasma cleaning, gold wire welding is used to connect the MEMS chip to the plastic package substrate printed with solder paste; Bottom filling, curing, refilling, vacuum degassing, curing; Perform bubble test after rapid pressure relief; Electrical testing, laser marking; S6. Re-cut the plastic-encapsulated substrate obtained through S5 into individual MEMS products to obtain individual MEMS products. Specifically: S61, laminating the plastic packaging body surface and the substrate surface of the plastic packaging substrate obtained by the step S6; S62, cutting the plastic package substrate from the plastic package surface; S63, performing UV debonding on the plastic package surface and the substrate surface respectively; S64, removing the adhesive film on the substrate surface; S65, transferring the single MEMS product with the adhesive film on the substrate removed to a loading tray; S66. Remove the film on the surface of the plastic package.

[0016] The above embodiment is further explained as follows: The present invention is an invention of a production process for a miniaturized pressure sensor suitable for automotive electronics.

[0017] The present invention develops a complete set of processes to solve the problems of maintaining high consistency between glue and MEMS products and difficulty in glue sealing when MEMS chips are mounted due to deformation of the plastic package body after plastic packaging.

[0018] First, if Figure 3 As shown, it is necessary to plastic-encapsulate the components and ASIC chip, and form two or more cavities for the placement of the MEMS chip and subsequent electrical connection (gold wire bonding process); However, after plastic sealing, the entire product will inevitably exhibit relatively large bending deformation, which will bring a series of problems to the subsequent glue dispensing, such as: poor flatness of the cavity where the chip is mounted, poor height consistency of the sealant after mounting, etc. The present invention can solve the above problems, thereby meeting the sealant thickness requirements under the MEMS product chip and achieving the requirements of high quality and high production capacity.

[0019] The present invention adopts the method of pre-cutting the whole substrate (more than 200 pieces) to a certain thickness after plastic packaging and before MEMS chip dispensing and chip mounting, so that the internal stress between the plastic packaging bodies can be released and the relative deformation can be greatly reduced to a very low level. Figure 4 The figure shows the schematic diagram after pre-cutting. At this point, the connection between the individual products is cut off and the stress is well released. When dispensing and chip placement, use Figure 9 The vacuum adsorption bottom fixture shown in the figure sucks the individual products flat one by one, so that the chip placement can meet the guarantee of glue height and glue uniformity. The glue height can be controlled within +-20UM. Figure 10 Shown is a schematic diagram and measurement results of the glue height measurement of the MEMS chip after mounting in the processed product; By solving the warpage problem, the traditional method of measuring the height of each product point by point before placement is no longer necessary. This eliminates the time required for measuring the height one by one, and allows for direct glue dispensing and chip placement. This overcomes the disadvantage of slow speed and achieves high-quality and high-speed operations. It also eliminates the risk of sudden product deformation after height measurement and before placement, enabling large-scale mass production with high quality and high yield. Through experiments, the optimal thickness was found to prevent the product from breaking and to eliminate overall bending deformation to achieve high quality and high yield. A special substrate fixture was designed to absorb the product so that the entire product is horizontal and free of deformation during operation.

[0020] When using the above-mentioned processing technology for multi-chip special-shaped plastic-encapsulated MEMS products, the problem of plastic package warping is solved before the chip is glued and mounted, so that glue dispensing and chip mounting can be directly performed without measuring the height of each product position. It can also eliminate the risk of sudden deformation of the product after measuring the height and before the mounting operation in the existing process, thereby achieving high-quality and high-speed operation, ensuring the quality and yield of large-scale mass production and reducing processing costs.

[0021] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A processing technology for multi-chip special-shaped plastic-encapsulated MEMS products, a single MEMS product includes: A product substrate (1), a plurality of components (2) disposed on the product substrate (1) and electrically connected to the product substrate (1), and a package (3) coated on the outside of the product substrate (1) and the components (2), characterized in that: an ASIC chip (4) and at least two MEMS chips (5) are also provided, the ASIC chip (4) electrically connected to the product substrate (1) is located in the package (3), each of the MEMS chips (5) is disposed in a containing cavity (6) surrounded by the package (3) and electrically connected to the product substrate (1), and the processing technology comprises the following steps: S1. Baking and solder paste printing on the entire substrate; S2, mounting components and multiple ASIC chips on the whole board substrate printed with solder paste obtained in S1; S3, performing plastic packaging on the whole board substrate with components and multiple ASIC chips mounted thereon obtained in S2, and forming at least two accommodating cavities on the outside of each ASIC chip through the packaging body during the packaging process; S4. Pre-cutting the plastic-encapsulated substrate encapsulating multiple ASIC chips obtained in S3 according to individual MEMS products, wherein the depth of the pre-cutting is less than the thickness of the plastic-encapsulated substrate, so that a cutting gap is formed between the package body of each MEMS product and the package body of an adjacent MEMS product and each MEMS product is still connected to its adjacent MEMS product; S5, for the plastic-encapsulated substrate pre-cut in S4, dispensing glue into the multiple accommodating cavities thereon and mounting the MEMS chip; S6. Recut the plastic-encapsulated substrate obtained through S5 processing according to a single MEMS product to obtain a single MEMS product.

2. The processing technology of multi-chip special-shaped plastic-sealed MEMS products according to claim 1 is characterized in that: Before step S5, the method further includes: using an adsorption fixture to adsorb and position the plastic-encapsulated substrate pre-cut in S4, wherein a carrier plate of the adsorption fixture is provided with a plurality of adsorption hole groups corresponding to the single MEMS product on the plastic-encapsulated substrate.

3. The processing technology of multi-chip special-shaped plastic-sealed MEMS products according to claim 1 or 2, characterized in that: Step S2 further comprises: S21, using a placement machine to mount components onto the entire board substrate printed with solder paste; S22, reflow soldering and automatic optical inspection after soldering; S23, cleaning the soldering flux and then baking it; S24, use glue to mount the ASIC chip on the whole board substrate and perform gold wire welding.

4. The processing technology of multi-chip special-shaped plastic-sealed MEMS products according to claim 1 or 2, characterized in that: Before step S6, the method further includes: Bake and solidify the plastic-sealed substrate with the MEMS chip mounted thereon; Conduct leakage tests on individual MEMS products on plastic-encapsulated substrates; After plasma cleaning, gold wire welding is used to connect the MEMS chip to the plastic package substrate printed with solder paste; Bottom filling, curing, refilling, vacuum degassing, curing; Perform bubble inspection after rapid pressure relief; Electrical testing, laser marking.

5. The processing technology of multi-chip special-shaped plastic-sealed MEMS products according to claim 1 or 2, characterized in that: Step S6 further comprises: S61, laminating the plastic encapsulation body surface and the substrate surface of the plastic encapsulation substrate obtained by the step S6; S62, cutting the plastic-encapsulated substrate from the surface of the plastic-encapsulated body; S63, performing UV debonding on the plastic package surface and the substrate surface respectively; S64, removing the adhesive film on the substrate surface; S65, transferring the single MEMS product from which the adhesive film on the substrate has been removed to a loading tray; S66. Remove the film on the surface of the plastic package.

6. The processing technology of multi-chip special-shaped plastic-sealed MEMS products according to claim 1 or 2, characterized in that: Step S1 also includes: optically inspecting the entire printed substrate.

Images