JP2011185704A - Humidity sensor module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin humidity sensor module having a waterproof function. <P>SOLUTION: The humidity sensor module is equipped with: a wiring board 20 provided in the state where a plurality of wiring conductors 21 are covered with an insulating layer 22 and a plurality of the electrode pads connected to a plurality of the wiring conductors 21 in a continuity state are exposed from the insulating layer 22; the humidity sensor package 30 having a humidity sensor element, an IC circuit board, a humidity suction port 31 for guiding the open air to the humidity sensor element, the sealing resin for sealing the IC circuit board and SMD terminals and mounted on the surface of the wiring board 20 by the electrical connection of a plurality of the SMD terminals and a plurality of the electrode pads corresponding to the wiring board 20; and the waterproof resin 50 for covering the sensor peripheral circuit part on the wiring board 20 and covering a plurality of the SMD terminals of the humidity sensor package 30 and a plurality of the electrode pads of the wiring board 20 in the state where the humidity suction port 31 is opened. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a humidity sensor module in which a humidity sensor and its peripheral circuit components are mounted on the same substrate.

  In recent years, sensors used for environmental change measurement have been required to be waterproof in addition to being small and thin so that they can be mounted on small electronic devices such as watches and mobile phones. In general, it is considered that the electronic components constituting the sensor and its peripheral circuits are electrically short-circuited and may be destroyed when wet. Specifically, as a waterproof structure of a humidity sensor, for example, as described in Patent Document 1, a structure in which the periphery of a humidity sensor is covered with a moisture-permeable waterproof and dustproof film is known.

Japanese Patent Laid-Open No. 2-107958 WO2009 / 119349

  However, if a structure that covers the periphery of the humidity sensor with a moisture-permeable waterproof and dust-proof film as in Patent Document 1 is used, a space for providing the moisture-permeable waterproof and dust-proof film is required, leading to an increase in size, and a small electronic device. It is difficult to install. Further, Patent Document 2 describes that a case made of a synthetic resin is provided on the outer periphery of the pressure sensor substrate to make the pressure sensor package a waterproof structure. It is disadvantageous for thinning. Thus, conventionally, there has been no small and thin humidity sensor having a waterproof function that can be mounted on a small electronic device.

  In view of the above problems, an object of the present invention is to provide a small and thin humidity sensor module having a waterproof function.

  The present invention has been completed in view of the fact that a waterproof function can be easily obtained simply by covering the humidity sensor package and its peripheral circuit components with a waterproof resin.

  That is, the present invention is capable of detecting the humidity, and a wiring board in which a plurality of wiring conductors are covered with an insulating layer, and a plurality of electrode pads electrically connected to the plurality of wiring conductors are exposed from the insulating layer. Humidity sensor element, an IC circuit board electrically connected to the humidity sensor element, a moisture suction port for introducing outside air to the humidity sensor element, and a sealing resin for sealing at least the IC circuit board with the moisture suction port open And a plurality of SMD terminals arranged on a surface different from a surface where the moisture absorption port of the humidity sensor element is opened and electrically connected to the IC circuit board, the plurality of SMD terminals and the wiring board A humidity sensor package surface-mounted on the wiring board by electrical connection with the corresponding electrode pads, and disposed on the wiring board, and at least one of the electrode pads on the wiring board Sensor peripheral circuit components electrically connected to the wiring board, and a plurality of SMD terminals of the humidity sensor package and the wiring board on the wiring board, covering the sensor peripheral circuit parts and opening the moisture absorption port. And a waterproof resin covering the plurality of electrode pads.

  The waterproof resin is provided with a thickness that exposes the moisture absorption port and completely covers the plurality of SMD terminals and the corresponding electrode pads of the wiring board and the sensor peripheral circuit component. preferable. According to this aspect, by controlling the thickness of the waterproof resin, it is easy to completely cover the plurality of SMD terminals, the corresponding electrode pads of the wiring board, and the sensor peripheral circuit components while the moisture absorption port is opened.

  It is practical to use a flexible wiring board as the wiring board.

  According to the present invention, the sensor mounting portion by electrical connection of the plurality of SMD terminals of the humidity sensor package and the corresponding plurality of electrode pads of the wiring board and the sensor peripheral circuit components mounted on the wiring board are protected by the waterproof resin. Therefore, it is possible to provide a humidity sensor module having a small and thin waterproof function.

It is a perspective view which shows one Embodiment of the humidity sensor module to which this invention is applied. It is a perspective view of the humidity sensor module which abbreviate | omits and shows waterproofing resin of FIG. FIG. 3 is a partially enlarged plan view showing the humidity sensor module of FIG. 2 as viewed from above. It is sectional drawing which follows the IV-IV line of FIG. It is an external appearance perspective view of a humidity sensor package. FIG. 6 is a perspective view of a humidity sensor package in which the sealing resin of FIG. 5 is omitted. It is a top view which shows the humidity sensor package of FIG. 6 seeing from the top.

  1 and 2 are perspective views showing an embodiment of a humidity sensor module to which the present invention is applied, FIG. 3 is a plan view showing the humidity sensor module as viewed from above, and FIG. 4 is taken along line IV-IV in FIG. It is sectional drawing. The humidity sensor module 10 is a humidity sensor module with a waterproof function in which the humidity sensor package 30 mounted on the wiring board 20 and its peripheral circuit components 40 are covered with a waterproof resin 50. The waterproof resin 50 is not shown in FIGS.

  The wiring board 20 is a deformable thin board having flexibility in which a plurality of wiring conductors 21 are covered with an insulating layer 22, and has a high degree of freedom when incorporated in a narrow space. In the present embodiment, an elongated rectangular flexible wiring board extended in the wiring direction is used as the wiring board 20. The plurality of wiring conductors 21 are electrically connected to each of a plurality of electrode pads (sensor mounting electrode pads) 23a and sensor peripheral circuit components 40 electrically connected to the humidity sensor package 30 on one end side in the extending direction. A plurality of electrode pads (circuit component mounting electrode pads) 23b are formed, and a plurality of electrode pads (external connection electrode pads) 23c used for external connection are formed on the other end side. All of the plurality of electrode pads 23a, 23b, and 23c are electrically connected to the corresponding wiring conductors 21 in the insulating layer 22 and exposed to the substrate surface 20a.

  As shown in detail in FIGS. 5 to 7, the humidity sensor package 30 includes a humidity sensor element 32 that detects humidity, and a moisture suction port 31 that protects the humidity sensor element 32 and introduces outside air into the humidity sensor element 32. A plurality of SMDs (Surface Mounts) made of a metal conductor provided on a surface different from the surface where the moisture absorption port 31 is opened, and an IC circuit board 350 electrically connected to the humidity sensor element 32. Device) and a mold package in which the humidity sensor element 32 and the IC circuit board 350 are covered with a sealing resin 36 made of, for example, epoxy resin or the like in a state where the moisture suction port 31 and the plurality of SMD terminals 37 are exposed. is there. 6 and 7, the sealing resin 36 constituting the upper surface of the package is not shown.

  The humidity sensor element 32, the protective member 311 that forms the moisture absorption port 31, the plurality of electrical wiring portions 33, and the electrode pads 34 are provided on the sensor chip substrate 310, and the sensor chip substrate 310 and the electrode pads 354 and 355 are provided. The IC circuit board 350 having the circuit board 350 is disposed on a single support board 300.

  In the illustrated embodiment, a moisture absorption port 31 is opened on the upper surface of the sensor (upward in the drawing), and a plurality of SMD terminals 37 are arranged on the lower surface of the sensor that is 180 ° opposite to the moisture absorption port 31. The humidity sensor package 30 is mounted on the surface 20 a of the wiring board 20 by electrical connection of the plurality of SMD terminals 37 and corresponding electrode pads (sensor mounting electrode pads) 23 a of the wiring board 20. For example, solder or a conductive adhesive can be used for mounting.

  The peripheral circuit component 40 includes, for example, a step-down circuit that generates an input voltage to the humidity sensor element 32 by dropping a supply voltage supplied from an external power source to a predetermined voltage, and a plurality of electronic components 41 such as filter capacitors and resistors. , 42, 43. Each electronic component 41, 42, 43 is electrically connected to a corresponding electrode pad (circuit component mounting electrode pad) 23 b of the wiring substrate 20 by, for example, solder or conductive adhesive, and is connected to the wiring substrate 20. The humidity sensor package 30 is mounted on the same surface. The type and number of peripheral circuit components 40 are not limited.

  The waterproof resin 50 is made of, for example, an epoxy resin and completely covers at least the plurality of SMD terminals 37 and the plurality of electrode pads 23a which are sensor mounting portions and the peripheral circuit components 40 (electronic components 41 to 43). The thickness of the waterproof resin 50 is controlled (set) so that the moisture suction port 31 of the humidity sensor package 30 is exposed and the plurality of SMD terminals 37, the plurality of electrode pads 23a, and the peripheral circuit component 40 are completely covered. . The waterproof resin 50 prevents the plurality of SMD terminals 37 of the humidity sensor package 30, the plurality of electrode pads 23 a and 23 b of the wiring board 20, and the peripheral circuit component 40 from getting wet with water. The short circuit between the plurality of SMD terminals 37 can be avoided. Thereby, reliability and durability are improved.

  The sensor chip substrate 310 is made of a silicon substrate having an insulating film on the surface of the Si layer, for example. The protective member 311 is formed so as to protrude on the humidity sensor element 32 and exposes only the moisture sensitive portion of the humidity sensor element 32 to the outside air from the moisture suction port 31. This protective member 311 is made of Si. The shape of the protection member 311 and the moisture absorption port 31 is arbitrary. One end of each of the plurality of electrical wiring portions 33 is electrically connected to the humidity sensor element 32, and an electrode pad 34 is provided on the other end. Specifically, the humidity sensor element 32 uses, for example, a polymer moisture sensitive material whose dielectric constant changes according to the amount of absorbed or released moisture as a moisture sensitive body, and detects the change in the dielectric constant as a capacitance change. A capacitance type or a resistance type that detects a change in electrical resistance according to the amount of absorbed or released moisture can be used. The humidity sensor element 32 of the present embodiment is a capacitance type that includes a reference portion whose output is constant regardless of humidity change and a moisture sensitive portion whose output varies according to humidity change. Since the moisture-sensitive part of the humidity sensor element is formed by selecting a moisture-sensitive polymer moisture-sensitive material for humidity detection, there is no possibility of causing operational problems even when wet.

  The IC circuit board 350 is a control circuit board that detects an output change of the humidity sensor element 32. The plurality of electrode pads 354 are electrically connected to the plurality of electrode pads 34 of the corresponding sensor chip substrate 310 through the conductive wires 38, and the electrode pads 355 for external connection are connected through the conductive wires 39. The contact conductor 307 provided on the surface of the support substrate 300 is electrically connected. The contact conductor 307 is conductively connected to the SMD terminal 37 provided on the back surface of the support substrate 300 through a through-hole conductor that penetrates the front and back surfaces of the support substrate 300.

  In the support substrate 300 to which the sensor chip substrate 310 and the IC circuit substrate 350 are bonded and fixed, the surface height is highest on the upper surface of the protection member 311, and the surface heights of the conductive wires 38 and 39 are the protection member. It is lower than the upper surface of 311. That is, the sensor chip substrate 310 and the IC circuit substrate 350 are completely covered with the sealing resin 36 except for the upper surface of the protective member 311.

  By using the humidity sensor package 30 which is this mold package, it becomes possible to mount the humidity sensor on the wiring board 20, and the humidity sensor package 30 excluding the moisture absorption port 31 and its peripheral circuit components 40 are covered with the waterproof resin 50. Waterproof function is obtained just by doing. The actual size of the humidity sensor package 30 is, for example, about 2.5 mm long, 2.3 mm wide, and 1 mm thick.

  In this humidity sensor module 10, the IC circuit board 350 and SMD terminal 37 of the humidity sensor package 30 and the peripheral circuit component 40 are waterproofed by the sealing resin 36 and the waterproof resin 50, and the wiring conductor 21 of the wiring board 20 is also an insulating layer. Even if the moisture sensitive part of the humidity sensor package 30 gets wet with water, there is no problem in operation. Therefore, when the humidity sensor module 10 is mounted on an electronic device, as shown in FIG. 1, the upper and lower sides of the wiring board 20 are closed and sealed by sandwiching them with, for example, rubber packing P, and exposed to moisture. And the region B that is not exposed to moisture can be used separately. Alternatively, without using the packing, after connecting a connection terminal (not shown) in the electronic device and an electrode pad (external connection electrode pad) 23c, the connection portion may be covered with a waterproof resin.

  As described above, according to the present embodiment, the humidity sensor package 30 and its peripheral circuit components 40 are mounted on the wiring board 20, and these electronic components are covered with the waterproof resin 50. The humidity sensor module 10 having a small and thin waterproof function that can be mounted in a space was realized. When the dimension example of the humidity sensor module of this embodiment is raised, it is about 6 mm in length, 30 mm in width, and 1 mm in thickness, for example.

10 Humidity sensor module 20 Wiring board (flexible wiring board)
20a Substrate surface 21 Wiring conductor 22 Insulating layer 23a Electrode pad (electrode pad for sensor mounting)
23b Electrode pad (Electrode pad for mounting circuit components)
23c Electrode pad (external connection electrode pad)
30 Humidity sensor package (humidity sensor)
31 Moisture Absorption Port 32 Humidity Sensor Element 33 Electrical Wiring Section 34 Electrode Pad 36 Sealing Resin (Package)
37 SMD terminal 38, 39 Conductive wire 40 Peripheral circuit component 41, 42, 43 Electronic component 50 Waterproof resin 300 Support substrate 307 Contact conductor 310 Sensor chip substrate 311 Protective member 350 IC circuit substrate 354, 355 Electrode pad

Claims (3)

A wiring board that covers a plurality of wiring conductors with an insulating layer, and that is provided with a plurality of electrode pads that are conductively connected to the plurality of wiring conductors exposed from the insulating layer;
A humidity sensor element that detects humidity, an IC circuit board that is electrically connected to the humidity sensor element, a moisture suction port that guides outside air to the humidity sensor element, and at least the IC circuit board is sealed with the moisture suction port open. A plurality of SMD terminals that are disposed on a surface different from a surface where the moisture absorption port of the sealing resin and the humidity sensor element is opened and electrically connected to the IC circuit board; and the plurality of SMD terminals A humidity sensor package surface-mounted on the wiring board by electrical connection with a corresponding plurality of electrode pads of the wiring board;
A sensor peripheral circuit component disposed on the wiring board and electrically connected to at least one of the plurality of electrode pads of the wiring board;
On the wiring board, a waterproof resin that covers the sensor peripheral circuit components and covers the plurality of SMD terminals of the humidity sensor package and the plurality of electrode pads of the wiring board with the moisture absorption opening opened.
A humidity sensor module comprising: 2. The humidity sensor module according to claim 1, wherein the waterproof resin exposes the moisture absorption port and completely covers the plurality of SMD terminals and the corresponding electrode pads of the wiring board and the sensor peripheral circuit component. Humidity sensor module provided in thickness. The humidity sensor module according to claim 1 or 2, wherein a flexible wiring board is used as the wiring board.

Images