A MEMS sensor stepped deep hole packaging structure and method

Abstract

The application provides a MEMS sensor stepped deep hole packaging structure and method, which comprises a substrate and a shell fixedly connected with the substrate, the shell is internally provided with a chip, the chip is fixedly connected with the substrate, a hole is formed on the side of the chip away from the shell, a first solder pad is arranged on the hole, a stepped hole is formed through the substrate, the stepped hole is arranged in a position opposite to the hole through a positioning tool, a second solder pad is arranged on the stepped hole, and the first solder pad is electrically connected with the second solder pad through a lead wire. The application can better release the stress caused by packaging by arranging the stepped hole, so that the precision is improved, and the adverse effects on the product precision caused by the traditional wire bonding on the plane are overcome.

Description

Technical Field

[0001] This invention relates to the field of MEMS sensor packaging technology, specifically to a stepped deep-hole packaging structure and method for MEMS sensors. Background Technology

[0002] MEMS refers to Micro-Electro-Mechanical Systems, which combines traditional integrated circuit technology and various microfabrication technologies. In recent years, it has gradually developed and improved, and can be applied to a great extent to benefit people's daily lives. With the rapid development of MEMS device design and fabrication, the design and manufacturing of MEMS devices have received increasing attention.

[0003] During the manufacturing, storage, and use of MEMS devices, multiple external environmental factors can negatively impact their reliability. Current MEMS sensor packaging methods limit the improvement of product accuracy. The goal for MEMS sensors is higher accuracy and feedback; existing packaging methods, such as LCC packaging, while aiming to maximize stress relief through new packaging techniques, make it difficult to significantly improve accuracy.

[0004] MEMS devices experience increased power consumption due to rising environmental and internal temperatures, coupled with inherent issues in the packaging process. Poor thermal matching between materials during packaging or use can lead to residual thermal stress and significantly increase the likelihood of device failure. Traditional flip-chip packaging methods typically use underfill to mitigate thermal mismatch between the chip, solder joints, and the packaging substrate. However, the small size of this sensor model makes the underfill process extremely complex, increasing production costs and limiting the applicability of traditional solutions. Summary of the Invention

[0005] In view of this, the problem to be solved by the present invention is to provide a stepped deep hole packaging structure for MEMS sensors.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a stepped deep hole packaging structure for a MEMS sensor, including a substrate and a housing fixedly connected to the substrate. A chip is built into the housing and fixedly connected to the substrate. A hole is opened on the side of the chip away from the housing. A first pad is provided on the hole. A stepped hole is opened through the substrate. The stepped hole is arranged opposite to the hole by a positioning fixture. A second pad is provided in the stepped hole. The first pad is electrically connected to the second pad by a lead wire.

[0007] In this invention, preferably, the stepped hole includes a first opening and a second opening, wherein the diameter of the first opening is smaller than the diameter of the second opening.

[0008] In this invention, preferably, the first opening is arranged facing the chip, and the second opening is arranged away from the chip.

[0009] In this invention, preferably, the positioning fixture has a first positioning groove, the first positioning groove has a second positioning groove, and a positioning post is fixed on the second positioning groove.

[0010] In this invention, preferably, the size of the positioning post matches the size of the hole.

[0011] In this invention, preferably, the size of the first positioning groove matches the size of the chip, and the size of the second positioning groove matches the size of the substrate.

[0012] In this invention, preferably, the positioning fixture has a fixture groove.

[0013] In this invention, preferably, the hole, the first opening, and the second opening are fixed together by an adhesive layer.

[0014] In this invention, preferably, the adhesive layer is a two-component addition-curing potting compound.

[0015] In this invention, preferably, the housing is provided with a through-hole for air venting.

[0016] A stepped deep-hole packaging method for MEMS sensors includes the following steps:

[0017] S1: Lay the chip on one side of the substrate, aligning the holes of the chip with the stepped holes;

[0018] S2: Enables the first pad inside the hole to be electrically connected to the second pad of the stepped hole via a lead wire;

[0019] S3: Fill the holes and stepped holes with potting compound and allow it to cure;

[0020] S4: Package the housing on the substrate;

[0021] S5: Perform encapsulation on the chip.

[0022] The advantages and positive effects of this invention are:

[0023] (1) By cooperating with the positioning fixture and the holes, stepped holes, first pads and second pads, the chip and the substrate can be quickly aligned during the chip packaging process. The first pad and the second pad are both set in the hole. On the one hand, it enhances the robustness of the substrate, chip and housing packaging structure. In addition, by setting the stepped hole, the stress brought by the packaging can be better released, thereby achieving the purpose of improving accuracy and overcoming the adverse effects on product accuracy caused by the traditional wire bonding which is carried out on the plane.

[0024] (2) By providing a positioning fixture with a first positioning slot, a second positioning slot and a positioning post, it is possible to quickly position the substrate and the chip during the packaging process. The placement and removal of the chip is made more convenient by setting the fixture slot. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0026] Figure 1 This is an overall structural cross-sectional view of a stepped deep-hole packaging structure for a MEMS sensor according to the present invention;

[0027] Figure 2 This is a schematic diagram of the positioning fixture for a stepped deep hole packaging structure of a MEMS sensor according to the present invention;

[0028] Figure 3 This is a schematic diagram of a stepped deep hole packaging method for MEMS sensors according to the present invention.

[0029] In the diagram: 1. Substrate; 2. Housing; 3. Chip; 4. Hole; 5. First pad; 6. Stepped hole; 7. Positioning fixture; 8. Second pad; 9. Lead wire; 10. First opening; 11. Second opening; 12. First positioning groove; 13. Second positioning groove; 14. Positioning post; 15. Fixture groove; 16. Vent hole. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] like Figures 1 to 2 As shown, the present invention provides a stepped deep hole packaging structure for a MEMS sensor, including a substrate 1 and a housing 2 fixedly connected to the substrate 1. A chip 3 is built into the housing 2 and the chip 3 is fixedly connected to the substrate 1. A hole 4 is opened on the side of the chip 3 away from the housing 2. A first pad 5 is provided on the hole 4. A stepped hole 6 is opened through the substrate 1. The stepped hole 6 is arranged opposite to the hole 4 by a positioning fixture 7. A second pad 8 is provided in the stepped hole 6. The first pad 5 is electrically connected to the second pad 8 by a lead wire 9. During encapsulation, the substrate 1 is first placed in the second positioning groove 13, so that the stepped hole 6 is placed in the positioning post 14. Then, the chip 3 is placed in the first positioning groove 12, and the hole 4 is fastened to the positioning post 14. The positioning fixture 7 is used to make the stepped hole 6 and the hole 4 face each other, thereby realizing the alignment process between the chip 3 and the substrate 1. A high-magnification lens can be used to detect whether the alignment is in place. Next, the first pad 5 is electrically connected to the second pad 8 through the lead wire 9. The lead wire 9 can be made of gold wire, and the connection between the two is realized through the gold wire bonding process. The hole 4, the first opening 10 and the second opening 11 are fixed together by an adhesive layer. The adhesive layer is set as a two-component addition-curing potting compound. The two-component addition-curing potting compound is used to fill the space between the substrate 1 and the chip 3 to achieve curing. Then, the chip 3 is encapsulated inside the housing 2 by setting a fixed connection between the housing 2 and the substrate 1. After the housing 2 is fixed, the space between the chip 3 and the housing 2 is potted.

[0034] In this embodiment, the stepped hole 6 further includes a first opening 10 and a second opening 11, wherein the diameter of the first opening 10 is smaller than that of the second opening 11. By setting the diameter of the first opening 10 to be smaller than that of the second opening 11, a stepped structure can be formed in the stepped hole 6 of the substrate 1, which facilitates the electrical connection of the pads and can better release stress to improve the accuracy of the product.

[0035] In this embodiment, the first opening 10 is arranged facing the chip 3, and the second opening 11 is arranged away from the chip 3. The first opening 10 is connected to the hole 6, which facilitates the electrical connection between the first pad 5 and the second pad 8 through the lead wire 9.

[0036] In this embodiment, the positioning fixture 7 further includes a first positioning groove 12, a second positioning groove 13, and a positioning post 14 fixed on the second positioning groove 13. A stepped hole 6 is placed inside the positioning post 14, and then the chip 3 is placed inside the first positioning groove 12, with the hole 4 fastened onto the positioning post 14. The positioning fixture 7 ensures that the stepped hole 6 and the hole 4 are aligned, thereby achieving the alignment process between the chip 3 and the substrate 1.

[0037] In this embodiment, the size of the positioning post 14 is further matched with the size of the hole 4, thereby facilitating the alignment of the chip 3 with the substrate 1.

[0038] In this embodiment, the size of the first positioning groove 12 is matched with the size of the chip 3, and the size of the second positioning groove 13 is matched with the size of the substrate 1.

[0039] In this embodiment, the positioning fixture 7 is further provided with a fixture slot 15.

[0040] In this embodiment, the hole 4, the first opening 10, and the second opening 11 are further fixed together by an adhesive layer. The adhesive layer fills the hole 4, the first opening 10, and the second opening 11, which can play a better role in curing the substrate 1 and the chip 3, and can improve stress release, thereby improving the precision of the product.

[0041] In this embodiment, the adhesive layer is further configured as a two-component addition-curing potting compound. The two-component addition-curing potting compound undergoes a cross-linking reaction and cures into a high-performance elastomer. It can cure at room temperature or be accelerated at temperatures below 80°C. During curing, the material exhibits no significant shrinkage or temperature rise. The cured elastomer possesses excellent electrical properties, aging resistance, high and low temperature resistance, waterproofing, moisture resistance, good deep curing, and does not corrode contact materials or pollute the surrounding environment.

[0042] In this embodiment, the housing 2 is further provided with a through-hole vent 16, which is suitable for situations where the device to be measured is in contact with the chip 3.

[0043] like Figure 3 As shown, a stepped deep-hole packaging method for a MEMS sensor is used in a stepped deep-hole packaging structure for a MEMS sensor, comprising the following steps:

[0044] S1: Lay the chip on one side of the substrate, aligning the holes of the chip with the stepped holes;

[0045] S2: Enables the first pad inside the hole to be electrically connected to the second pad of the stepped hole via a lead wire;

[0046] S3: Fill the holes and stepped holes with potting compound and allow it to cure;

[0047] S4: Package the housing on the substrate;

[0048] S5: Perform potting process on the chip.

[0049] The working principle and process of this invention are as follows: During packaging, the substrate 1 is first placed in the second positioning groove 13, so that the stepped hole 6 is placed in the positioning post 14. Then, the chip 3 is placed in the first positioning groove 12, and the hole 4 is fastened to the positioning post 14. The positioning fixture 7 is used to make the stepped hole 6 and the hole 4 face each other, thereby realizing the alignment process between the chip 3 and the substrate 1. Furthermore, by setting a high-magnification lens, it is possible to detect whether the chip 3 and the substrate 1 are properly aligned. Next, the first pad 5 is electrically connected to the second pad 8 through the lead wire 9. The lead wire 9 can be made of gold wire, and the gold wire bond is used to connect the two pads. The connection between the two is achieved through a combined process. Hole 4, first opening 10 and second opening 11 are fixed together by an adhesive layer. The adhesive layer is a two-component addition-curing potting compound. The two-component addition-curing potting compound is used to fill the space between the substrate 1 and the chip 3 to achieve curing. Then, by setting a fixed connection between the housing 2 and the substrate 1, the chip 3 is encapsulated inside the housing 2. After the housing 2 is fixed, the space between the chip 3 and the housing 2 is potted. The vent hole 16 opened on the surface of the housing 2 is suitable for situations where the chip 3 is in contact with the measurement.

[0050] By cooperating with the positioning fixture 7, the hole 4, the stepped hole 6, the first pad 5, and the second pad 8, the chip 3 and the substrate 1 can be quickly aligned during the chip 3 packaging process. The first pad 5 and the second pad 8 are both set inside the hole, which on the one hand enhances the robustness of the packaging structure of the substrate 1, the chip 3, and the housing 2. On the other hand, by setting the stepped hole 6, the stress brought by the packaging can be better released, thereby achieving the purpose of improving accuracy and overcoming the adverse effects on product accuracy caused by the traditional wire bonding being performed on a plane.

[0051] The positioning fixture 7, which has a first positioning groove 12, a second positioning groove 13 and a positioning post 14, facilitates rapid positioning between the substrate 1 and the chip 3 during the packaging process. The fixture groove 15 makes it more convenient to pick up and put down the chip 3.

[0052] The adhesive used in the potting process primarily serves to disperse stress. Two-component addition-curing potting compounds undergo cross-linking via an addition reaction, curing into a high-performance elastomer. It consists of two liquid components, A and B. Component A is black or white, and component B is white. When the two components are thoroughly mixed in a 1:1 weight ratio, the mixture cures into a soft elastomer. It can cure at room temperature or at temperatures below 80°C for accelerated curing. During curing, the material exhibits no significant shrinkage or temperature rise. The cured elastomer possesses excellent electrical properties, aging resistance, resistance to high and low temperatures (-60 to 200°C), waterproofing, moisture resistance, good deep curing, and does not corrode contact materials or pollute the surrounding environment. Suffixes indicate the cured color: W (white), B (black), G (gray), R (red), L (transparent).

[0053] 1. Weighing: Accurately weigh components A and B (stir components A and B thoroughly before weighing to ensure that any settled filler is evenly dispersed in the adhesive); components A and B should be thoroughly mixed in a 1:1 (by weight) ratio.

[0054] 2. Mixing: Add component B to component A and stir until well mixed and the adhesive has a uniform color. Mixing can be done manually or using automatic mixing and dispensing equipment. When mixing manually, be careful not to mix too much adhesive at once, otherwise the fluidity will decrease and it will be difficult to pour later.

[0055] 3. Degassing: Place the well-mixed adhesive in a vacuum chamber to degas, removing entrained air by vacuuming.

[0056] 4. Pouring: Pour the degassed adhesive into the parts to complete the potting operation (keep the surface of the parts and the mixing container clean and dry before potting).

[0057] 5. Curing: Cure the potted parts at room temperature or with heat. At room temperature, the viscosity of the mixed colloid will gradually increase over time, doubling within 40-60 minutes.

[0058] The primary function of MEMS packaging is to ensure that devices remain unaffected under various operating conditions, providing support for internal components and extending their lifespan. Stress in MEMS devices and their packages mainly originates from the manufacturing and operational processes. During manufacturing, such as in the processing of thin-film materials, various methods like laser-induced chemical or physical vapor deposition, plasma etching, and thermochemical vapor deposition create varying degrees of mechanical stress within the material. During device operation, residual thermal stress generated due to changes in ambient temperature can often have a fatal impact. Excessive residual thermal stress is often caused by significant differences in the coefficients of thermal expansion between materials. Therefore, during the initial packaging design phase, it is crucial to select packaging materials with coefficients of thermal expansion close to those of the chip material to minimize the generation of excessive thermal stress. This can also be achieved by improving the packaging structure.

[0059] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of this patent.

Claims

1. A stepped deep-hole packaging structure for a MEMS sensor, characterized in that, The device includes a substrate (1) and a housing (2) fixedly connected to the substrate (1). A chip (3) is built into the housing (2). The chip (3) is fixedly connected to the substrate (1). A hole (4) is opened on the side of the chip (3) away from the housing (2). A first pad (5) is provided on the hole (4). A stepped hole (6) is opened through the substrate (1). The stepped hole (6) is arranged opposite to the hole (4) by a positioning fixture (7). A second pad (8) is provided on the stepped hole (6). The first pad (5) is electrically connected to the second pad (8) by a lead wire (9). The stepped hole (6) includes a first opening (10) and a second opening (11). The first opening (10) is arranged on the side facing the chip (3), and the second opening (11) is arranged on the side away from the chip (3). The diameter of the first opening (10) is smaller than the diameter of the second opening (11).

2. The stepped deep-hole packaging structure for a MEMS sensor according to claim 1, characterized in that, The positioning fixture (7) has a first positioning groove (12), the first positioning groove (12) has a second positioning groove (13), and a positioning post (14) is fixed on the second positioning groove (13).

3. The stepped deep-hole packaging structure for a MEMS sensor according to claim 2, characterized in that, The dimensions of the positioning post (14) are matched with the dimensions of the hole (4).

4. The stepped deep-hole packaging structure for a MEMS sensor according to claim 3, characterized in that, The size of the first positioning groove (12) matches the size of the chip (3), and the size of the second positioning groove (13) matches the size of the substrate (1).

5. The stepped deep-hole packaging structure for a MEMS sensor according to claim 1, characterized in that, The positioning fixture (7) has a fixture slot (15).

6. The stepped deep-hole packaging structure for a MEMS sensor according to claim 1, characterized in that, The hole (4), the first opening (10) and the second opening (11) are fixed together by an adhesive layer.

7. The stepped deep-hole packaging structure for a MEMS sensor according to claim 6, characterized in that, The adhesive layer is configured as a two-component addition-type potting compound.

8. The stepped deep-hole packaging structure for a MEMS sensor according to claim 1, characterized in that, The shell (2) has a through-hole (16).

9. A method for encapsulating a stepped deep hole in a MEMS sensor, used in the stepped deep hole encapsulation structure for a MEMS sensor as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1: Lay the chip on one side of the substrate, aligning the holes of the chip with the stepped holes; S2: Enables the first pad inside the hole to be electrically connected to the second pad of the stepped hole via a lead wire; S3: Fill the holes and stepped holes with potting compound and allow it to cure; S4: Package the housing on the substrate; S5: Perform potting process on the chip.

Images