WO2020258117A1 - Mems压力传感器封装结构及封装方法 - Google Patents

Mems压力传感器封装结构及封装方法 Download PDF

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Publication number
WO2020258117A1
WO2020258117A1 PCT/CN2019/093154 CN2019093154W WO2020258117A1 WO 2020258117 A1 WO2020258117 A1 WO 2020258117A1 CN 2019093154 W CN2019093154 W CN 2019093154W WO 2020258117 A1 WO2020258117 A1 WO 2020258117A1
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Prior art keywords
pressure sensor
mems pressure
circuit board
packaging
flexible circuit
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PCT/CN2019/093154
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English (en)
French (fr)
Inventor
陈创录
李志强
张劭龙
张以涛
侯喆
张海英
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中国科学院微电子研究所
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Priority to PCT/CN2019/093154 priority Critical patent/WO2020258117A1/zh
Publication of WO2020258117A1 publication Critical patent/WO2020258117A1/zh

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate

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  • the present disclosure relates to the technical field of pulse sensors, in particular to a MEMS pressure sensor packaging structure and packaging method.
  • Micro-Electro-Mechnical-System (MEMS) pressure sensors generally include supporting beams or supporting membrane structures. Most of their sensor principles use the principle of stress and strain. Take MEMS pressure sensors as an example, which supports beams under different pressure levels. Or the strain degree of the supporting film is different, causing the resistance value of the resistance structure on the MEMS air pressure sensor to change, destroying the balance of the Wheatstone bridge, and generating a changing voltage signal.
  • MEMS pressure sensors Take MEMS pressure sensors as an example, which supports beams under different pressure levels. Or the strain degree of the supporting film is different, causing the resistance value of the resistance structure on the MEMS air pressure sensor to change, destroying the balance of the Wheatstone bridge, and generating a changing voltage signal.
  • the electrical connection between the MEMS sensor and the substrate such as PCB substrate or plastic cavity metal lead frame
  • the substrate such as PCB substrate or plastic cavity metal lead frame
  • a MEMS pressure sensing device for measuring human pulse that collects pulse fluctuations through a hydraulic bionic probe.
  • the hydraulic bionic probe is fixed with a double-layer strap.
  • the hydraulic bionic probe can be detected by the pressure medium in the hydraulic bionic probe.
  • the change of the pressure signal received is transmitted to the pressure sensor.
  • the pressure transmission medium is water
  • the micro-sensor array technology is adopted, and the 24-bit sensor measures the parameter properties of the pulse wave number.
  • this kind of pulse wave sensor uses water to conduct the pulse signal, and the hydraulic conduction tube is likely to cause greater interference, and the pulse wave information cannot be accurately obtained, which is of little diagnostic significance.
  • the length of the liquid conduit is 30 cm, resulting in poor portability of the device.
  • a finger pressure and microarray sensing device for measuring human pulse.
  • MEMS technology a microarray pressure sensor is designed. The sensor is placed in an arc-shaped rigid material similar to the size of the finger pad of the index finger, and then MEMS packaging is performed , Simulate human finger touch information, get pulse diagnosis information.
  • MEMS packaging is performed , Simulate human finger touch information, get pulse diagnosis information.
  • the micro-pressure contact of the MEMS microarray sensor is embedded on the outer surface of the flexible finger pressure probe designed with the bionic finger pad, and the sensitive surface of the sensor and the bonding gold wire are not protected, and the sensor is easily damaged.
  • the present disclosure provides a MEMS pressure sensor packaging structure and packaging method, in order to at least partially solve the above technical problems.
  • a MEMS pressure sensor packaging structure including:
  • a MEMS pressure sensor fixed on a surface of the flexible circuit board and electrically connected to the flexible circuit board through a gold wire, the MEMS pressure sensor including a pressure sensitive structure;
  • the rigid housing forms an open cavity, and the MEMS pressure sensor is placed in the open cavity;
  • a packaging filler filled in the open cavity and covering the pressure sensitive structure of the MEMS pressure sensor and the exposed gold wire, and a protrusion is formed outside the open cavity;
  • the packaging filler can conduct pulse pressure to the pressure sensitive structure of the MEMS pressure sensor, so that the MEMS pressure sensor can collect pulse pressure signals.
  • a pulse detection device adopting the MEMS pressure sensor packaging structure as described above.
  • the number of the MEMS pressure sensors in the pulse detection device is multiple, which are used to collect different positions respectively.
  • the pulse pressure signal at the place is provided.
  • a MEMS pressure sensor packaging method including the following steps:
  • the packaging filler is poured into the open cavity to cover the pressure sensitive structure of the MEMS pressure sensor and the exposed gold wire, and a protrusion is formed outside the open cavity; wherein the package is filled
  • the agent can conduct the pulse pressure to the pressure sensitive structure of the MEMS pressure sensor, so that the MEMS pressure sensor can collect the pulse pressure signal.
  • Fig. 1 is a schematic diagram of the MEMS pressure sensor package structure of the present disclosure
  • FIG. 2(a) is a top view of the pressure sensitive structure of the MEMS silicon piezoresistive pressure sensor of Embodiment 1 of the present disclosure
  • Fig. 2(b) is a side view of the pressure sensitive structure of the MEMS silicon piezoresistive pressure sensor according to Embodiment 1 of the present disclosure
  • FIG. 2(c) is a schematic circuit diagram of the MEMS silicon piezoresistive pressure sensor of Embodiment 1 of the present disclosure.
  • 1-silica gel 2-rigid shell; 3-gold wire; 4-MEMS silicon piezoresistive pressure sensor; 5-FPC board; 6-reinforcement board; 7-through hole; 8-protrusion.
  • a MEMS pressure sensor packaging structure including:
  • FPC board Flexible Printed Circuit
  • the MEMS pressure sensor is fixed on a surface of the FPC board and is electrically connected to the flexible circuit board through a gold wire.
  • the MEMS pressure sensor includes a pressure sensitive structure
  • the rigid shell forms an open cavity with a MEMS pressure sensor inside;
  • the packaging filler is filled into the open cavity, covers the pressure sensitive structure of the MEMS pressure sensor and the exposed gold wire, and forms a protrusion outside the open cavity to facilitate pulse detection;
  • the packaging filler can conduct pulse pressure to the pressure sensitive structure of the MEMS pressure sensor, and the MEMS pressure sensor collects the pulse pressure signal.
  • the rigid shell is made of stainless steel, copper, aluminum, or resin materials that can form a rigid structure, such as ABS (Acrylonitrile Butadiene Styrene) resin;
  • the open cavity formed on the rigid shell can be opened up and down, so that the rigid shell only protects the side ; It can also be open in one direction, that is, the MEMS pressure sensor is mounted on a flexible circuit board covered by a rigid shell, and its pressure-sensitive structure is exposed from the through hole of the flexible circuit board, facing the open side of the rigid shell, covering the package
  • the filler forms protrusions.
  • the encapsulation filler is circuit board encapsulating silica gel, preferably polydimethylsiloxane (PDMS), etc.; more preferably, circuit board encapsulating silica gel that can solidify by itself, which makes the encapsulation process simpler and has better structural stability, such as AB glue, circuit board component fixing glue, etc.
  • PDMS polydimethylsiloxane
  • the rigid housing is fixed on the flexible circuit board, preferably by welding or bonding. It is easy to understand that if the rigid shell is made of metal material, it can be fixed on multiple pads of the flexible circuit board by soldering, for example, on the four pads at the four corners; if the rigid shell is made of resin, it can be bonded by adhesive. Fixed on the flexible layer of the flexible circuit board.
  • the MEMS pressure sensor packaging structure further includes a reinforcing plate, which is arranged on the other surface of the FPC board of the unfixed MEMS pressure sensor at a position opposite to the open cavity, and the size of the reinforcing plate is greater than or equal to The opening of the open cavity of the rigid housing.
  • the reinforcement board is a rigid board.
  • the reinforcement board is a glass fiber board, such as FR4. It can be hot pressed or glued to the FPC board to prevent the partial FPC board from bending, so as not to affect the packaging structure .
  • the FPC board and the reinforcing board are respectively provided with a through hole at a position corresponding to the MEMS pressure sensor to expose the MEMS pressure sensor, so that the MEMS pressure sensor is located in an atmospheric pressure environment.
  • the MEMS pressure sensor includes a plurality of pins
  • the FPC board has a plurality of first pads corresponding to the pins
  • the plurality of pins are respectively welded to the plurality of first pads through gold wires.
  • the MEMS pressure sensor is also fixed on the FPC board by welding.
  • the MEMS pressure sensor is a silicon piezoresistive pressure sensor
  • the corresponding pressure sensitive structure is a stress cup structure formed by a silicon sensitive film fixed on the periphery.
  • a pulse detection device using the MEMS pressure sensor packaging structure as described above wherein the number of MEMS pressure sensors can be multiple to form an array structure for collecting different Pulse signal at the position; in some embodiments, the multiple MEMS pressure sensors are fixed on the same flexible circuit board, thereby forming a plurality of protective structures corresponding to the rigid housing on a flexible circuit board.
  • a packaging method of a MEMS pressure sensor which includes the following steps:
  • Step S1 Fix the MEMS pressure sensor on a surface of a flexible circuit board, and electrically connect it to the flexible circuit board through a gold wire;
  • Step S2 Place the MEMS pressure sensor in a rigid housing with an open cavity
  • Step S3 Pour the packaging filler into the open cavity to cover the pressure sensitive structure of the MEMS pressure sensor and the exposed gold wire, and form a protrusion outside the open cavity;
  • the packaging filler can transmit the pulse pressure to the pressure sensitive structure of the MEMS pressure sensor, so that the MEMS pressure sensor can collect the pulse pressure signal.
  • step S1 a plurality of first pads and a plurality of second pads are formed on the flexible circuit board, and the plurality of first pads are respectively connected with a plurality of pins on the MEMS pressure sensor; the plurality of second pads are used for welding Fix the rigid shell.
  • the pads can be fabricated in a conventional manner, and will not be repeated here.
  • step S1 a reinforcing plate is formed at a position opposite to the open cavity on the other surface of the FPC board where the MEMS pressure sensor is not provided; and the size of the reinforcing plate is greater than or equal to that of the open cavity of the rigid housing Opening; the reinforcement board is attached to the PFC board by hot pressing or glue.
  • through holes are respectively preset on the FPC board and the reinforcement at the positions corresponding to the MEMS pressure sensor to expose the MEMS pressure sensor.
  • step S1 several pins of the MEMS pressure sensor are electrically connected to several first pads on the FPC board through a bonding gold wire process.
  • step S2 includes the following operations: buckle the rigid housing on the flexible circuit board where the MEMS pressure sensor is fixed, so that the MEMS pressure sensor chip and the exposed gold wire are contained in the open cavity of the rigid housing.
  • the rigid shell is preferably soldered and fixed on several second pads of the flexible circuit board.
  • the rigid shell made of resin can be directly bonded to the flexible circuit board through an adhesive.
  • the present embodiment takes a conventional MEMS silicon piezoresistive pressure sensor as an example, and designs an FPC board 5 with multiple pads made for the MEMS silicon piezoresistive pressure sensor 4 at corresponding positions on the front side.
  • Four of the pads correspond to the four pins of the MEMS silicon piezoresistive pressure sensor 4, the other pad is used to fix the MEMS silicon piezoresistive pressure sensor 4, and the other pad is used to fix the rigid housing 2;
  • a through hole 7 is preset in the middle of the reinforcing plate 6 and the FPC board 5 respectively, which corresponds to the fixed position of the MEMS silicon piezoresistive pressure sensor.
  • the MEMS silicon piezoresistive pressure sensor 4 is smeared with silver paste on the sensor fixing pad of the FPC board 5, and then baked at a set temperature for a certain period of time, which can fix the MEMS silicon piezoresistive pressure sensor 4 on the FPC On board 5.
  • Figures 2(a) ⁇ 2(b) are schematic diagrams of the pressure sensitive structure of the MEMS silicon piezoresistive pressure sensor 4, which is a stress cup structure formed by a fixed silicon sensitive film on the periphery, and stress on the surface of the silicon sensitive film
  • Four varistors R1 to R4 are made at the largest place to form a Wheatstone bridge as shown in Figure 2(c).
  • the circuit board encapsulated silica gel 1 is used for potting, and the surface tension of the circuit board encapsulated silica gel 1 is used to form a protrusion 8 outside the open cavity to facilitate Check the pulse, and then dry it in a ventilated place.
  • the circuit board encapsulated silica gel 1 is in contact with the sensitive structure of the MEMS silicon piezoresistive pressure sensor 4, which can conduct external pressure.
  • the rigid shell 2 is, for example, a metal shell made of brass, which is easy to install and use, has a thin shell wall and good rigidity.
  • the FPC board When the packaging method and packaging structure provided by this embodiment are applied to pulse measurement, the FPC board is used, so that the overall structure can be bent, and it can be closely attached to the pulse measurement position such as the human wrist, and the circuit board is packaged
  • the silica gel transmits the arterial movement at the measurement position to the sensitive structure of the sensor, and generates a voltage signal output.
  • the present disclosure fixes the MEMS sensor on the flexible circuit board and provides a rigid housing with an open cavity, so that the MEMS sensor is placed in the open cavity, and the packaging filler is filled in the open cavity.
  • the packaging filler can transmit the pulse pressure signal of the human body, and the gold wire is not easy to be damaged when placed in a rigid shell.
  • the flexible circuit board allows the MEMS pressure sensor to be bent, so as to closely fit the pulse measurement position
  • the packaging filler can not only transmit the pulse pressure signal, but also make the gold wire receive the same pressure in all directions, and it is more difficult to break. However, there is no report in the field of electrical protection through this soft contact.
  • the circuit board encapsulated silica gel is further used as the packaging filler to conduct pressure to the MEMS pressure sensor, which overcomes the defects of sealing or easy leakage when water is used as the conductive medium.
  • the silica gel will solidify by itself, and the preparation process is simpler and more stable. The performance is better, the sensitivity is high, and the structure is not easily damaged.

Abstract

一种MEMS压力传感器封装结构及封装方法。该封装结构包括柔性电路板（5）；MEMS压力传感器（4），固定于柔性电路板（5）的一表面，并与柔性电路板（5）电气连接，其包含压力敏感结构；刚性外壳（2），形成一开放式容腔，开放式容腔内容置有MEMS压力传感器（4）；以及封装填充剂（1），填充于开放式容腔，并覆盖于MEMS压力传感器（4）的压力敏感结构及裸露的金线（3）上，且在开放式容腔外形成一凸起部（8）；其中，封装填充剂（1）能将脉搏压力传导至MEMS压力传感器（4）的压力敏感结构，使MEMS压力传感器（4）能够采集脉搏压力信号。通过在MEMS压力传感器（4）周围固定刚性外壳（2），保护其与基板的电气连接，用封装填充剂（1）作为压力传导的介质，提高了传感器的稳定性和灵敏度。

Description

MEMS压力传感器封装结构及封装方法 技术领域
本公开涉及脉搏传感器技术领域，尤其涉及一种MEMS压力传感器封装结构及封装方法。
背景技术
随着社会经济的发展和人民生活水平的提高，人体健康监护越来越受到人们的关注。随着近年来传感器科学与技术的进步以及健康监护设备对压力传感器的特殊需求，市场上出现了越来越多种的脉搏传感器的结构设计。这些传感器体积小，结构稳定，可以持续监测人体健康状态，为人民提供最及时的健康预警服务。
微机电系统(Micro-Electro-Mechnical-System，MEMS)压力传感器一般包括支撑梁或支撑薄膜结构，其传感器原理大多采用应力应变原理，以MEMS气压传感器为例，其在不同的气压大小下支撑梁或支撑薄膜的应变程度不同，引起MEMS气压传感器上的电阻结构的阻值发生变化，破坏惠斯通电桥的平衡，从而产生变化的电压信号。
但是，由于MEMS传感器与基底例如PCB基板或塑料空腔金属引线框架等的电气连接一般采用邦定金线的方法，而金线是直接裸露的，在测量人体脉搏压力时，很容易破坏脆弱的金线，从而破坏传感器的正常使用。另外，目前有一种用于测量人体脉搏的MEMS压力传感装置是通过液压仿生探头采集脉搏波动，液压仿生探头采用双层束带固定，通过液压仿生探头内的传压介质可以将液压仿生探头检测到的压力信号的变化传递至压力传感器。其中，传压介质是水，并且采用微传感器阵列技术，24位传感器测量脉搏波位数形势参数属性。但是该种脉搏波传感器采用水传导脉搏信号，液压传导管很容易引起较大的干扰，不能准确地获取脉搏波信息，诊断意义不大。另外，液体导管的长度为30cm，导致该装置便携性较差。
还有一种用于测量人体脉搏的指感施压与微阵列传感装置，运用MEMS技术，设计微阵列压力传感器，将传感器置于类似食指指腹大小 的弧形刚性材料中，再进行MEMS封装，模拟人指下触感信息，获取脉诊信息。但是该装置中，MEMS微阵列传感器微压触点嵌合在仿生手指指肚设计柔性指压式探头的外表面，未对传感器的敏感面和邦定的金线进行保护，传感器容易损坏。
综上所述，现有技术中尚没有一种用于检测脉搏的MEMS压力传感装置，既能保护MEMS传感器与基底的电气连接，又能传导来自人体脉搏的压力信号。
发明内容
本公开提供了一种MEMS压力传感器封装结构及封装方法，以期至少部分地解决上述技术问题。
为实现上述目的，本公开的技术方案如下：
作为本公开的一个方面，提供了一种MEMS压力传感器封装结构，包括：
柔性电路板；
MEMS压力传感器，固定于所述柔性电路板的一表面，并与所述柔性电路板通过金线电气连接，所述MEMS压力传感器包含压力敏感结构；
刚性外壳，形成一开放式容腔，所述开放式容腔内容置有所述MEMS压力传感器；以及
封装填充剂，填充于所述开放式容腔，并覆盖于所述MEMS压力传感器的压力敏感结构及裸露的金线上，且在开放式容腔外形成一凸起部；
其中，所述封装填充剂能将脉搏压力传导至所述MEMS压力传感器的压力敏感结构，使MEMS压力传感器能够采集脉搏压力信号。
根据本公开的另一个方面，提供了一种采用如上所述的MEMS压力传感器封装结构的脉搏检测装置，所述脉搏检测装置中所述MEMS压力传感器的数量为多个，用于分别采集不同位置处的脉搏压力信号。
根据本公开的再一个方面，提供了一种MEMS压力传感器封装方法，包括以下步骤：
将MEMS压力传感器固定于一柔性电路板的一表面上，并通过金线电气连接至所述柔性电路板；
将所述MEMS压力传感器置于一具有开放式容腔的刚性外壳内；
将封装填充剂灌入所述开放式容腔内，覆盖所述MEMS压力传感器的压力敏感结构以及裸露的金线上，且在开放式容腔外形成一凸起部；其中，所述封装填充剂能将脉搏压力传导至MEMS压力传感器的压力敏感结构上，使MEMS压力传感器能够采集脉搏压力信号。
附图说明
图1是本公开的MEMS压力传感器封装结构示意图；
图2(a)是本公开实施例1的MEMS硅压阻式压力传感器的压力敏感结构俯视图；
图2(b)是本公开实施例1的MEMS硅压阻式压力传感器的压力敏感结构侧视图；
图2(c)是本公开实施例1的MEMS硅压阻式压力传感器的电路原理图。
上述附图中附图标记含义如下：
1-硅胶；2-刚性外壳；3-金线；4-MEMS硅压阻式压力传感器；5-FPC板；6-补强板；7-通孔；8-凸起部。
具体实施方式
根据本公开的一些实施例，提供了一种MEMS压力传感器封装结构，包括：
柔性电路板(Flexible Printed Circuit，以下简称FPC板)；
MEMS压力传感器，固定于FPC板的一表面，并与柔性电路板通过金线电气连接，MEMS压力传感器包含压力敏感结构；
刚性外壳，形成一开放式容腔，该开放式容腔内容置有MEMS压力传感器；以及
封装填充剂，填充至该开放式容腔内，覆盖于MEMS压力传感器的压力敏感结构及裸露的金线上，且在开放式容腔外形成一凸起部，以便于脉搏检测；
其中，所述封装填充剂能将脉搏压力传导至MEMS压力传感器的压 力敏感结构，而由MEMS压力传感器采集脉搏压力信号。
其中，刚性外壳为不锈钢、铜、铝或能够形成刚性结构的树脂材料如ABS(Acrylonitrile Butadiene Styrene)树脂等；该刚性外壳上形成的开放式容腔可以是上下开口的，从而刚性外壳只是保护侧面；也可以是一个方向开口的，即MEMS压力传感器安装在刚性外壳覆盖的柔性电路板上，其压力敏感结构从柔性线路板的通孔处曝露出来，朝向刚性外壳的开口侧，其上覆盖封装填充剂形成凸起。
其中，封装填充剂为电路板封装硅胶，优选为聚二甲基硅氧烷(PDMS)等；更优选为能够自行凝固的电路板封装硅胶，使得封装工艺更简单、结构稳定性更好，如AB胶、线路板元件固定胶等。
其中，刚性外壳固定于柔性电路板上，优选为通过焊接或粘接固定于柔性电路板上。容易理解，若刚性外壳为金属材料，例如可以通过焊接固定于柔性电路板的多个焊盘上，例如四个角上的四个焊盘上；若刚性外壳为树脂材质，则通过胶粘剂粘接固定于柔性电路板的柔性层上。
其中，该MEMS压力传感器封装结构还包括补强板，设置于FPC板的未固定MEMS压力传感器的另一表面上，与开放式容腔相对的位置处，且补强板的尺寸大于或等于所述刚性外壳的开放式容腔的开口。该补强板为刚性板，在一些实施例中，该补强板为玻璃纤维板，如FR4等，可以通过热压或胶粘于FPC板上，防止局部的FPC板弯折，以免影响封装结构。
其中，FPC板和补强板上分别在与MEMS压力传感器对应的位置设置有一通孔以裸露出MEMS压力传感器，使MEMS压力传感器位于大气压环境。
其中，MEMS压力传感器包含若干引脚，FPC板上具有与这些引脚对应的若干第一焊盘，该若干引脚分别通过金线焊接至该若干第一焊盘。此外，MEMS压力传感器也是通过焊接方式固定于FPC板上。
其中，MEMS压力传感器为硅压阻式压力传感器，相应的压力敏感结构为由周边固定的硅敏感膜形成的应力杯结构。
根据本公开的一些实施例，还提供了一种采用如上所述的MEMS 压力传感器封装结构的脉搏检测装置，其中，MEMS压力传感器的数量可为多个，以形成阵列结构，用于分别采集不同位置处的脉搏信号；在一些实施例中，该多个MEMS压力传感器固定于同一柔性电路板上，从而在一柔性电路板上形成多个与之对应的刚性外壳的保护结构。
根据本公开的一些实施例，还提供了一种MEMS压力传感器的封装方法，包括以下步骤：
步骤S1：将MEMS压力传感器固定于一柔性电路板的一表面上，并通过金线电气连接至柔性电路板；
步骤S2：将MEMS压力传感器置于一具有开放式容腔的刚性外壳内；
步骤S3：将封装填充剂灌入开放式容腔内，覆盖MEMS压力传感器的压力敏感结构以及裸露的金线上，且在开放式容腔外形成一凸起部；
其中，封装填充剂能将脉搏压力传导至MEMS压力传感器的压力敏感结构上，使MEMS压力传感器能够采集脉搏压力信号。
步骤S1中，在柔性电路板上形成若干第一焊盘以及若干第二焊盘，该若干第一焊盘分别与MEMS压力传感器上的若干引脚进行连接；该若干第二焊盘用于焊接固定刚性外壳。焊盘可通过常规方式制作形成，在此不作赘述。
步骤S1中，在FPC板的未设置MEMS压力传感器的另一表面上与开放式容腔相对的位置形成补强板；且补强板的尺寸大于或等于所述刚性外壳的开放式容腔的开口；补强板通过热压或胶粘贴附在PFC板上。
进一步地，在FPC板和补强上与MEMS压力传感器对应的位置分别预设置通孔，以裸露出MEMS压力传感器。
步骤S1中，MEMS压力传感器的若干引脚是通过邦定金线工艺与FPC板上的若干第一焊盘实现电气连接。
其中，步骤S2包括以下操作：将刚性外壳扣合在固定有MEMS压力传感器的柔性电路板上，使MEMS压力传感器芯片以及裸露的金线容置于该刚性外壳的开放式容腔内。刚性外壳优选是焊接固定于柔性电路板的若干第二焊盘上，当然树脂材质的刚性外壳则可直接通过胶粘剂粘 接在柔性电路板上。
以下通过具体实施例结合附图对本公开的技术方案作进一步说明：
实施例1
如图1所示，本实施例以常规MEMS硅压阻式压力传感器为例，设计一个FPC板5，其正面的相应位置处有为MEMS硅压阻式压力传感器4制作的多个焊盘，其中四个焊盘与MEMS硅压阻式压力传感器4的四个引脚一一对应，其中另一个焊盘用于固定MEMS硅压阻式压力传感器4，其中再一个焊盘用于固定刚性外壳2；在相应位置的背面有一块覆盖了四个焊盘的补强板6。补强板6和FPC板5的中间分别预设有一个通孔7，与MEMS硅压阻式压力传感器的固定位置相对应。
将MEMS硅压阻式压力传感器4用银浆涂抹于FPC板5的传感器固定位的焊盘上，然后以设定温度烘烤若干时间，这可以将MEMS硅压阻式压力传感器4固定在FPC板5上。如图2(a)～2(b)所示为MEMS硅压阻式压力传感器4的压力敏感结构的示意图，为由周边固定的硅敏感膜形成的应力杯结构，并在硅敏感膜表面应力最大处制作四个压敏电阻R1～R4，组成如图2(c)所示的惠斯通电桥。
使用仪器将MEMS硅压阻式压力传感器4的四个引脚邦定金线3，使其与FPC板5上的四个焊盘一一对应焊接，实现了MEMS硅压阻式压力传感器4与FPC板5的电气连接。在FPC板5上的刚性外壳固定位的焊盘处，用银浆或焊锡将设计、制作好的刚性外壳2的一端焊接到FPC板5上。
在焊接好的刚性外壳2所围成的开放式容腔内，用电路板封装硅胶1灌封，利用电路板封装硅胶1自身的表面张力在开放式容腔外形成一凸起部8，以便于脉搏检测，然后在通风处晾干，此时电路板封装硅胶1与MEMS硅压阻式压力传感器4的敏感结构相接触，可传导外界压力。刚性外壳2例如是黄铜制作的金属外壳，安装使用方便，壳壁薄，刚性好。
利用本实施例提供的封装方法以及封装结构在应用至脉搏测量时， 由于使用的是FPC板，使得整体结构能弯曲，与脉搏测量位置如人体腕部等能紧密贴合，而通过电路板封装硅胶将测量位置处的动脉运动情况传到至传感器的敏感结构上，产生电压信号输出。
通过实验验证可以发现，与现有技术比，本公开具有以下显著优点：
1、本公开将MEMS传感器固定到柔性电路板上，提供一具有开放式容腔的刚性外壳，使该MEMS传感器置于开放式容腔内，并在开放式容腔内填充封装填充剂，通过封装填充剂可以传导人体的脉搏压力信号，而金线放置在刚性外壳内也不易被损坏。
2、该柔性电路板使得MEMS压力传感器可以被弯曲，进而与脉搏测量位置能够紧密贴合；
3、另外，封装填充剂除了可以传导脉搏压力信号外，还能使金线各方向受到压强相同，更不易断裂，而通过这种软接触实现电气保护目前在本领域中还未见报道。
4、进一步采用电路板封装硅胶作为封装填充剂来传导压力到MEMS压力传感器，克服了以水作为传导介质时需要密封或者容易泄露的缺陷，封装时，硅胶会自行凝固，制备工艺更简单，稳定性更好，灵敏度高，结构不易损坏。
以上所述的具体实施例，对本公开的目的、技术方案和有益效果进行了进一步详细说明，应理解的是，以上所述仅为本公开的具体实施例而已，并不用于限制本公开，凡在本公开的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (21)

  1. 一种MEMS压力传感器封装结构，其特征在于，包括：
    柔性电路板；
    MEMS压力传感器，固定于所述柔性电路板的一表面，并与所述柔性电路板通过金线电气连接，所述MEMS压力传感器包含压力敏感结构；
    刚性外壳，形成一开放式容腔，且所述开放式容腔内容置有所述MEMS压力传感器；以及
    封装填充剂，填充于所述开放式容腔，并覆盖于所述MEMS压力传感器的压力敏感结构及裸露的金线上，且在开放式容腔外形成一凸起部；
    其中，所述封装填充剂能将脉搏压力传导至所述MEMS压力传感器的压力敏感结构，使MEMS压力传感器能够采集脉搏压力信号。
  2. 根据权利要求1所述的MEMS压力传感器封装结构，其特征在于，所述刚性外壳通过焊接或胶粘固定于所述柔性电路板上。
  3. 根据权利要求2所述的MEMS压力传感器封装结构，其特征在于，刚性外壳通过焊接固定于所述柔性电路板的若干焊盘上。
  4. 根据权利要求2所述的MEMS压力传感器封装结构，其特征在于，所述MEMS压力传感器封装结构还包括补强板，设置于所述柔性电路板的未固定所述MEMS压力传感器的另一表面上，且补强板的尺寸大于或等于所述刚性外壳的开放式容腔的开口。
  5. 根据权利要求4所述的MEMS压力传感器封装结构，其特征在于，所述补强板为刚性板，通过热压或胶粘贴附在柔性电路板上。
  6. 根据权利要求5所述的MEMS压力传感器封装结构，其特征在于，所述柔性电路板和补强板分别在与MEMS压力传感器对应的位置处设置有一通孔，以裸露出所述MEMS压力传感器。
  7. 根据权利要求1所述的MEMS压力传感器封装结构，其特征在于：
    所述MEMS压力传感器为硅压阻式压力传感器，所述压力敏感结构为由周边固定的硅敏感膜形成的应力杯结构。
  8. 根据权利要求1所述的MEMS压力传感器封装结构，其特征在 于，所述刚性外壳的材质选自不锈钢、铜、铝或能够形成刚性结构的树脂材料。
  9. 根据权利要求1所述的MEMS压力传感器封装结构，其特征在于，所述封装填充剂为电路板封装硅胶。
  10. 根据权利要求9所述的MEMS压力传感器封装结构，其特征在于，所述封装填充剂为聚二甲基硅氧烷。
  11. 一种采用如权利要求1～10任一项所述的MEMS压力传感器封装结构的脉搏检测装置，其特征在于，所述脉搏检测装置中所述MEMS压力传感器的数量为多个，用于分别采集不同位置处的脉搏压力信号。
  12. 根据权利要求11所述的脉搏检测装置，其特征在于，所述多个MEMS压力传感器固定于同一柔性电路板上。
  13. 一种MEMS压力传感器的封装方法，其特征在于，包括以下步骤：
    步骤S1：将MEMS压力传感器固定于一柔性电路板的一表面上，并通过金线电气连接至所述柔性电路板；
    步骤S2：将所述MEMS压力传感器置于一具有开放式容腔的刚性外壳内；
    步骤S3：将封装填充剂灌入所述开放式容腔内，覆盖所述MEMS压力传感器的压力敏感结构以及裸露的金线上，且在开放式容腔外形成一凸起部；其中，所述封装填充剂能将脉搏压力传导至MEMS压力传感器的压力敏感结构上，使MEMS压力传感器能够采集脉搏压力信号。
  14. 根据权利要求13所述的封装方法，其特征在于，步骤S2具体包括：
    将一刚性外壳扣合在固定有MEMS压力传感器的柔性电路板上，使所述MEMS压力传感器以及裸露的金线容置于所述刚性外壳的开放式容腔内。
  15. 根据权利要求14所述的封装方法，其特征在于作为优选，通过焊接或胶粘将所述刚性外壳固定于所述柔性电路板上。
  16. 根据权利要求15所述的封装方法，其特征在于，通过焊接将 所述刚性外壳固定于所述柔性电路板的若干焊盘上。
  17. 根据权利要求14所述的封装方法，其特征在于，步骤S1中，所述柔性电路板上形成有若干第一焊盘和若干第二焊盘，所述若干第一焊盘用于分别与所述MEMS压力传感器上的若干引脚进行连接，所述若干第二焊盘用于固定所述刚性外壳。
  18. 根据权利要求17所述的封装方法，其特征在于，步骤S1中，所述MEMS压力传感器的若干引脚是通过邦定金线工艺与所述柔性电路板的若干第一焊盘实现电气连接。
  19. 根据权利要求14所述的封装方法，其特征在于，步骤S1或S2中，还包括在所述柔性电路板的未固定MEMS压力传感器的另一表面的对应于开放式容腔的位置处固定补强板的步骤，其中所述补强板的尺寸大于或等于所述刚性外壳的开放式容腔的开口。
  20. 根据权利要求19所述的封装方法，其特征在于，所述补强板通过热压或胶粘贴附在所述柔性电路板上。
  21. 根据权利要求19所述的封装方法，其特征在于，在所述柔性电路板和补强板上与MEMS压力传感器对应的位置处分别预设置通孔，以能够裸露出所述MEMS压力传感器。
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