Direct measurement packaging structure suitable for MEMS flat film pressure chip

Abstract

The invention provides a direct measurement packaging structure suitable for an MEMS flat membrane pressure chip. The direct measurement packaging structure comprises a protective cover, a signal processing circuit, a metal base, a switching PCB, a square-head ceramic column and the MEMS flat membrane pressure chip. The metal base is provided with a first cavity and a second cavity, and a through hole is formed between the first cavity and the second cavity; the signal processing circuit and the switching PCB are arranged in the first cavity and are electrically connected through wires. The square-head ceramic column is arranged at the through hole of the metal base, one end of the square-head ceramic column is connected with the switching PCB, and the other end of the square-head ceramic column penetrates through the through hole and is located in the second cavity; the second cavity is used for fixing the flat membrane pressure chip and is connected with one end of the square-head ceramic column; the protective cover is arranged at the top of the metal base and is used for sealing the first cavity; the square-head ceramic column is adopted to replace a lead, so that the risk of short circuit between the lead and a metal hole wall can be avoided; electrical interconnection of the pressure chips is achieved through flip-chip bonding, higher connection strength and reliability are guaranteed, leadless connection of the pressure chips is achieved through flip-chip bonding, and signal interference is reduced.

Description

Technical Field

[0001] This invention belongs to the field of pressure chip pressure testing, and specifically relates to a direct test packaging structure suitable for MEMS flat film pressure chips. Background Technology

[0002] In the field of MEMS pressure sensors, flat-film pressure chips have pads designed on the back of the chip, while vias in the center of the substrate material ensure the pads are exposed, allowing the entire front of the chip to be used for pressure-sensitive structure design. Compared to conventional pressure chips that place metal pads on the front, flat-film pressure chips offer superior environmental resistance, do not require dielectric isolation protection and can be directly used for dielectric measurement, and also exhibit better dynamic response.

[0003] Flat diaphragm pressure chips need to be packaged into pressure sensors or pressure transmitters for pressure measurement. To ensure a rapid and accurate dynamic pressure response, the pressure chip is typically mounted close to the measured medium. Due to the threaded connections and sealing structures of pressure measurement devices, the pressure chip is relatively far from the downstream signal processing circuitry, with a long, narrow through-hole in between. Because of these structural limitations, conventional wire bonding processes struggle to prevent short circuits between the multiple leads and the metal substrate hole walls, making it difficult to achieve a stable and reliable electrical connection. Furthermore, excessively long leads are prone to deformation or even breakage, reducing product reliability. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes a direct-test packaging structure suitable for MEMS flat film pressure chips. This structure includes: a protective cover, a signal processing circuit, a metal base, an adapter PCB, a square-headed ceramic pillar, and the MEMS flat film pressure chip. The metal base is provided with a first cavity and a second cavity, with a through-hole between the first and second cavities. The signal processing circuit and the adapter PCB are both located within the first cavity and are electrically connected by wires. The square-headed ceramic pillar is located at the through-hole of the metal base, with one end connected to the adapter PCB and the other end passing through the through-hole and located within the second cavity. The second cavity is used to fix the MEMS flat film pressure chip and is connected to one end of the square-headed ceramic pillar. The protective cover is located on top of the metal base to seal the first cavity.

[0005] The beneficial effects of this invention are:

[0006] This invention employs a ceramic powder sintering process to fabricate square-headed ceramic pillars with metal leads, replacing wires and avoiding the risk of short circuits between the leads and the metal hole walls. It also avoids the difficulties of bonding wires in narrow holes, resulting in higher reliability. This invention uses flip-chip bonding for electrical interconnection of the pressure chip, ensuring higher connection strength and reliability, significantly improving resistance to high-frequency shocks and vibrations, and enhancing environmental adaptability. This invention uses flip-chip bonding to achieve leadless connection of the pressure chip, ensuring synchronous and consistent signal transmission, reducing signal interference, and enabling high-precision pressure measurement. Attached Figure Description

[0007] Figure 1 This is a structural diagram of the flat film pressure chip of the present invention;

[0008] Figure 2 This is a direct-test packaging structure diagram of the flat film pressure chip of the present invention;

[0009] Figure 3 This is a partially enlarged view of the direct-test packaging structure of the flat film pressure chip of the present invention. Detailed Implementation

[0010] 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.

[0011] This invention relates to a direct-measurement packaging structure suitable for MEMS flat diaphragm pressure chips. This structure not only ensures the reliability of the sealed connection for measurement and the rapid dynamic response of the measurement, but also solves the problem of stable and reliable electrical connection between the flat diaphragm pressure chip and the signal processing circuit. It offers high fabrication feasibility and is suitable for pressure measurement in various complex environments.

[0012] In this embodiment, a direct-test packaging structure suitable for MEMS flat film pressure chips is disclosed, such as... Figures 1-3 As shown, it includes: a protective cover, a signal processing circuit, a metal base, an adapter PCB, a square-headed ceramic pillar, and a MEMS flat film pressure chip; the metal base is respectively provided with a first cavity and a second cavity, and a through hole is provided between the first cavity and the second cavity; the signal processing circuit and the adapter PCB are both located in the first cavity and are electrically connected by wires; the square-headed ceramic pillar is located at the through hole of the metal base, with one end connected to the adapter PCB and the other end passing through the through hole and located in the second cavity; the second cavity is used to fix the MEMS flat film pressure chip and is connected to one end of the square-headed ceramic pillar; the protective cover is located on the top of the metal base and is used to seal the first cavity.

[0013] In this embodiment, the protective cover is provided with a hole for leading out the output signal wire of the signal processing circuit and connecting it to an external circuit.

[0014] Furthermore, the inner side of the protective cover is provided with an internal thread, and the outer side of the top of the metal base is provided with an external thread. The internal thread on the inner side of the protective cover matches the external thread on the metal base, so that the protective cover can be tightly fixed on the metal base.

[0015] A through-hole is provided on the substrate of the MEMS flat film pressure chip; the pad of the flat film pressure chip is set on the pressure-sensitive structure and located at the through-hole of the substrate, so that one end of the square-headed ceramic pillar is electrically connected to the pad of the flat film pressure chip through the through-hole.

[0016] Preferably, the substrate is a silicon / glass substrate, which is bonded to the pressure-sensitive structure to form a stable and reliable integrated structure.

[0017] The metal pins of the square-headed ceramic pillar correspond to the pads of the MEMS flat film pressure chip, and the metal pins and chip pads are flip-chip bonded at high temperature using a flip-chip soldering machine to achieve electrical connection between the metal pins and the flat film pressure chip.

[0018] In this embodiment, the first cavity has a stepped structure, that is, the first cavity is divided into a large cavity and a small cavity. The bottom of the small cavity is provided with a groove, and one end of the square-headed ceramic pillar is placed in the groove. The metal pin of the square-headed ceramic pillar passes through the metallized through hole on the adapter PCB, and the adapter PCB and the metal pin are fixed by adhesive and solder respectively.

[0019] The direct-test package structure also includes a sealing ring. When performing pressure measurement, the threaded interface of the direct-test package structure is pre-tightened with the interface of the pressure to be measured and sealed by pre-pressurization through the sealing ring to complete the dynamic pressure measurement.

[0020] In this embodiment, to ensure a stable and reliable electrical connection between the flat-film pressure chip and the signal processing circuit, a square-headed ceramic pillar with metal leads is fabricated using a ceramic powder sintering process. The arrangement of the metal leads on the square-headed ceramic pillar corresponds one-to-one with the arrangement of the chip pads and the arrangement of the metallized vias on the adapter PCB. One end of the metal lead is connected to the adapter PCB via through-hole soldering, while the other end uses flip-chip soldering to achieve an electrical connection between the metal lead and the chip pads. Simultaneously, to ensure sealing, sealant is applied around the MEMS flat-film pressure chip.

[0021] A direct-test packaging structure suitable for MEMS flat film pressure chips is implemented as follows: First, a square-headed ceramic pillar with metal leads is customized according to the pad layout and substrate via size of the flat film pressure chip. The surface of the metal leads needs to be gold-plated. The square-headed ceramic pillar is installed in the base, with the square end of the ceramic pillar mating with the square mounting groove of the base for positioning and fixed with high-temperature resistant adhesive. Depending on the flip-chip bonding material, screen printing or ball-mounting machine can be used to place the metal balls on the pads of the flat film pressure chip. The shape and size of the metal balls must be consistent. Next, the flat film pressure chip is placed on the square-headed ceramic pillar according to the pad layout. The square mounting groove at the bottom of the base is designed according to the chip size to ensure that the metal leads do not misalign with the chip pads. A flip-chip bonding machine is used to perform high-temperature flip-chip bonding between the metal leads and the chip pads, achieving electrical connection between the metal leads and the MEMS flat film pressure chip. Finally, sealant is applied around the chip to complete the sealing and protection. Next, install the adapter PCB in the corresponding position inside the base cavity, ensuring that the metal pins on the square ceramic pillar pass correctly through the metallized through holes on the adapter PCB. Use adhesive and solder to fix the adapter PCB and metal pins respectively. Then, use signal wires or connectors to connect the adapter PCB to the signal processing circuit. Finally, tighten the threads of the protective cover to complete the encapsulation of the pressure sensor.

[0022] When performing pressure measurement, simply mate the threaded interface of the direct-measurement encapsulation structure with the interface of the pressure to be measured, pre-tighten it, and pre-press it with a sealing ring to achieve dynamic pressure measurement.

[0023] In the description of this invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "other end," "upper," "side," "top," "inner," "outer," "front," "center," "both ends," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "rotation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] The above-described embodiments further illustrate the purpose, technical solution, and advantages of the present invention. It should be understood that the above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A direct-test packaging structure suitable for MEMS flat film pressure chips, characterized in that, include: The device comprises a protective cover, a signal processing circuit, a metal base, an adapter PCB, a square-headed ceramic pillar, and a MEMS flat film pressure chip. The metal base has a first cavity and a second cavity, with a through hole between them. The signal processing circuit and the adapter PCB are both located in the first cavity and are electrically connected by wires. The square-headed ceramic pillar is located at the through hole of the metal base, with one end connected to the adapter PCB and the other end passing through the through hole and located in the second cavity. The second cavity is used to fix the MEMS flat film pressure chip and is connected to one end of the square-headed ceramic pillar. The protective cover is located on top of the metal base and is used to seal the first cavity.

2. The direct-test packaging structure for MEMS flat film pressure chips according to claim 1, characterized in that, The protective cover has holes for leading out the output signal wires of the signal processing circuit and connecting them to external circuits.

3. The direct-test packaging structure for MEMS flat film pressure chips according to claim 2, characterized in that, The inner side of the protective cover is provided with an internal thread, and the outer side of the top of the metal base is provided with an external thread. The internal thread on the inner side of the protective cover matches the external thread on the metal base, so that the protective cover can be tightly fixed on the metal base.

4. The direct-test packaging structure for MEMS flat film pressure chips according to claim 1, characterized in that, A through-hole is provided on the substrate of the MEMS flat film pressure chip; the pad of the flat film pressure chip is set on the pressure-sensitive structure and located at the through-hole of the substrate, so that one end of the square-headed ceramic pillar is electrically connected to the pad of the flat film pressure chip through the through-hole.

5. The direct-test packaging structure for MEMS flat film pressure chips according to claim 4, characterized in that, The substrate is a silicon / glass substrate, which is bonded to the pressure-sensitive structure to form a stable and reliable integrated structure.

6. The direct-test packaging structure for MEMS flat film pressure chips according to claim 4, characterized in that, The metal pins of the square-headed ceramic pillar correspond to the pads of the MEMS flat film pressure chip, and the metal pins and chip pads are flip-chip bonded at high temperature using a flip-chip soldering machine to achieve electrical connection between the metal pins and the flat film pressure chip.

7. The direct-test packaging structure for MEMS flat film pressure chips according to claim 4, characterized in that, The first cavity has a stepped structure, that is, the first cavity is divided into a large cavity and a small cavity. The bottom of the small cavity is provided with a groove, and one end of the square-headed ceramic pillar is placed in the groove. The metal pin of the square-headed ceramic pillar passes through the metallized through hole on the adapter PCB, and the adapter PCB and the metal pin are fixed with adhesive and solder respectively.

8. The direct-test packaging structure for MEMS flat film pressure chips according to claim 1, characterized in that, In addition to being fixed by flip-chip bonding, the MEMS flat diaphragm pressure chip is also sealed and secondary fixed by sealant in the second cavity.

9. A direct-test packaging structure suitable for MEMS flat film pressure chips according to claim 1, characterized in that, The direct-test package structure also includes a sealing ring. When performing pressure measurement, the threaded interface of the direct-test package structure is pre-tightened with the interface of the pressure to be measured and sealed by pre-pressurization through the sealing ring to complete the dynamic pressure measurement.

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