Sensor module having conductive bonding members with varying melting points and young's moduli

A sensor module includes: a substrate including a first terminal and a second terminal; a first conductive bonding member having a first melting point and a first Young's modulus; a lead bonded to the first terminal by the first conductive bonding member; a second conductive bonding member having a second melting point lower than the first melting point and a second Young's modulus higher than the first Young's modulus; and an inertial sensor bonded to the second terminal by the second conductive bonding member.

The present application is based on, and claims priority from JP Application Serial Number 2021-028264, filed Feb. 25, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a sensor module.

2. Related Art

In related art, as described in JP-A-10-242633, it is known that when an electronic device is manufactured by soldering and fixing, to a substrate, an electronic component such as a piezoelectric element in which a piezoelectric element piece is fixed in an airtight package, a solder having a high melting temperature is used in a previous operation of soldering and fixing, and a solder having a low melting temperature is used in a subsequent operation of soldering and fixing, so that the subsequent soldering does not affect the previous soldering due to different melting temperatures of solders.

Unfortunately, in the electronic device described in JP-A-10-242633, as a solder material having a lower melting temperature, for example, a Sn—Bi eutectic solder is used, which has low mechanical strength and thermal fatigue resistance and is not sufficient in reliability as a solder for the electronic device. For this reason, when the solders in the electronic device described in JP-A-10-242633 are selectively used and applied to, for example, a sensor module in which an inertial sensor such as an acceleration sensor or an angular velocity sensor is mounted at a substrate, there is a problem that in an environment for using the sensor module, a stress caused by a difference in thermal expansion coefficients of the inertial sensor and the substrate is repeatedly applied to the solder as a bonding portion between the inertial sensor and the substrate, and thus the solder deteriorates and the sensor module becomes unstable in function and decreased in reliability.

SUMMARY

A sensor module includes: a substrate, including a first surface and a second surface on front and back sides of each other, a first terminal provided at one of the first surface and the second surface, and a second terminal provided at the first surface; a lead bonded to the first terminal; a first conductive bonding member having a first melting point and a first Young's modulus, and bonding the lead and the first terminal; an inertial sensor bonded to the second terminal; and a second conductive bonding member having a second melting point lower than the first melting point and a second Young's modulus higher than the first Young's modulus, and bonding the inertial sensor and the second terminal.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

1. First Embodiment

A sensor module1according to the first embodiment will be described with reference toFIGS.1to4.FIG.1illustrates a state in which a top plate70of a cap7is removed for convenience of describing an internal configuration of the sensor module1. InFIG.4, for convenience of describing an internal configuration of a first inertial sensor31, components other than an acceleration sensor element310, an angular velocity sensor element3r, and internal electrodes313are omitted. Dimensional ratios of each component in each drawing are different from actual dimension ratios.

As to coordinates illustrated in the drawings, three axes orthogonal to each other are referred to as an X axis, a Y axis, and a Z axis. A direction along the X axis is defined as an “X direction”, a direction along the Y axis is defined as a “Y direction”, and a direction along the Z axis is defined as a “Z direction”, in each of which a direction indicated by an arrow is a plus direction. In addition, the plus direction in the Z direction is referred to as “up” or “upper”, and a minus direction in the Z direction is referred to as “down” or “lower”. Further, when viewed from a top in the Z direction, a surface at a plus side in the Z direction is referred to as an upper surface, and a surface at a minus side in the Z direction opposite to the upper surface is referred to as a lower surface.

As shown inFIGS.1to3, the sensor module1includes: a substrate2; the cap7bonded to a first surface21of the substrate2; an inertial sensor3bonded to the first surface21; a lead9bonded to a second surface22of the substrate2, the second surface22and the first surface21being on front and back sides of each other; and a circuit element8bonded to the second surface22. In the present embodiment, the first surface21of the substrate2is an upper surface of the substrate2, and the second surface22is a lower surface of the substrate2.

First terminals292as external coupling terminals of the sensor module1, and third terminals296as internal coupling terminals of the sensor module1are provided at the second surface22of the substrate2. The first terminals292are bonded to the lead9via first conductive bonding members51. In the present embodiment, the first terminals292are provided at the second surface22, but may also be provided at the first surface21. In other words, the first terminals292may be provided at one of the first surface21and the second surface22.

Each third terminal296is bonded to the circuit element8via a third conductive bonding member53.

The first surface21of the substrate2is provided with second terminals294as internal coupling terminals of the sensor module1. Each second terminal294is bonded to the inertial sensor3via a second conductive bonding member52.

As shown inFIGS.1and2, the substrate2is a printed circuit board. In the present embodiment, the substrate2has a rectangular plate-like shape when viewed from the top in the Z direction orthogonal to the first surface21. The substrate2may be, for example, a ceramic substrate, a glass epoxy substrate, or the like. For convenience of description, wiring formed at the substrate2is not illustrated, while only the second terminals294provided at the first surface21, and the first terminals292and the third terminals296provided at the second surface22are illustrated. The first terminals292, the second terminals294, and the third terminals296are electrically coupled to the wiring (not shown) formed at the substrate2.

When viewed from the top in the Z direction, the substrate2includes a first side2A, a second side2B facing the first side2A, a third side2C adjacent to the first side2A and the second side2B, and a fourth side2D facing the third side2C.

In the first surface21of the substrate2, a first concave portion23A is provided at the first side2A, a second concave portion23B is provided at the second side2B, a third concave portion23C is provided at the third side2C, and a fourth concave portion23D is provided at the fourth side2D.

Next, each portion located at a first surface21side of the substrate2will be described.

As shown inFIGS.1and3, the inertial sensor3is bonded to the first surface21of the substrate2. By bonding the cap7to the first surface21, the inertial sensor3is accommodated between the first surface21and the cap7.

When viewed from the top in the Z direction, the cap7has a rectangular shape substantially similar to the substrate2. The cap7may be formed of, for example, alloy42, which is an iron-nickel alloy.

The cap7includes the top plate70, a side wall71extending downward from an outer peripheral edge of the top plate70, a concave portion711formed by the top plate70and the side wall71, and a first convex portion72A, a second convex portion72B, a third convex portion72C, and a fourth convex portion72D protruding inward from a lower end portion of the side wall71.

When viewed from the top in the Z direction, the convex portions72A,72B,72C, and72D of the cap7respectively overlap the concave portions23A,23B,23C, and23D of the substrate2.

The first convex portion72A of the cap7is bonded to the first concave portion23A of the substrate2via a bonding member (not shown). Similarly, the second convex portion72B, the third convex portion72C, and the fourth convex portion72D of the cap7are respectively bonded to the second concave portion23B, the third concave portion23C, and the fourth concave portion23D of the substrate2via bonding members (not shown).

The cap7is bonded to the first surface21of the substrate2, so that the inertial sensor3is accommodated in the concave portion711.

The inertial sensor3includes the first inertial sensor31, a second inertial sensor32, and an angular velocity sensor33.

The first inertial sensor31and the second inertial sensor32are so-called six-axis inertial sensors, which detect angular velocities around three axes including the X axis, the Y axis, and the Z axis and accelerations in directions along the three axes. The angular velocity sensor33is provided to accurately detect an angular velocity around a desired detection axis among the three axes including the X axis, the Y axis, and the Z axis. In the present embodiment, the angular velocity sensor33detects the angular velocity around the Z axis. The inertial sensor3is not limited to such a configuration, and may be a sensor that detects at least one of an acceleration in a direction along each axis or an angular velocity around each axis.

The inertial sensor3includes coupling terminals301at a lower surface of the inertial sensor3. The coupling terminals301are used to input a control signal for controlling the inertial sensor3to the inertial sensor3, and to output a detection signal such as the acceleration or the angular velocity detected by the inertial sensor3from the inertial sensor3.

The coupling terminals301are bonded to the second terminals294provided at the first surface21of the substrate2via the second conductive bonding members52, so that the coupling terminals301are electrically coupled to the second terminals294, and the inertial sensor3is fixed to the first surface21of the substrate2.

In the present embodiment, the second conductive bonding member52is a lead-free solder, and a symbol indicating a composition thereof is Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni. The symbols indicating the composition are expressed according to the Japanese Industrial Standard Z3282:2017. Specifically, the symbols indicating the composition show element symbols of the elements mainly forming the lead-free solder and weight ratios of the elements. For example, Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni omits indication showing a weight ratio of tin (Sn) as balance, and indicates the weight ratios of the elements other than tin (Sn), specifically indicating that 3.0% of silver (Ag), 0.8% of copper (Cu), 3.0% of bismuth (Bi), and 0.02% of nickel (Ni) are contained.

Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni used as the second conductive bonding member52has a melting point of 205° C. and a Young's modulus of 52.2 GPa. In other words, when Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni is used as the second conductive bonding member52, a second melting point as the melting point of the second conductive bonding member52is 205° C., and a second Young's modulus as the Young's modulus of the second conductive bonding member52is 52.2 GPa.

Unlike a eutectic solder such as Sn—Bi and Sn—In, an alloy-based lead-free solder such as Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni is in a state in which a solid phase and a liquid phase coexist. Therefore, two temperatures including a solidus temperature and a liquidus temperature are defined as temperatures indicating a melting state of the solder, and the melting point in the present disclosure is the solidus temperature. The Young's modulus is a measured value at 25° C.

Here, the first inertial sensor31and the second inertial sensor32in the present embodiment will be described.

As illustrated inFIG.4, when viewed from the top in the Z direction, the first inertial sensor31has a rectangular shape enclosed by long sides311and short sides312having a length different from that of the long sides311. In the present embodiment, the long sides311are parallel to the X direction, and the short sides312are parallel to the Y direction.

The first inertial sensor31includes the acceleration sensor element310, the angular velocity sensor element3r, and plural internal electrodes313electrically coupled to the acceleration sensor element310and the angular velocity sensor element3rby wiring (not shown).

The acceleration sensor element310and the angular velocity sensor element3rare disposed side by side in the X direction along the long sides311.

The acceleration sensor element310includes an X-axis acceleration sensor element3xthat detects the acceleration in the X direction along the long sides311, a Z-axis acceleration sensor element3zthat detects the acceleration in the Z direction perpendicular to a plane including the long sides311and the short sides312, and a Y-axis acceleration sensor element3ythat detects the acceleration in the Y direction along the short sides312.

The X-axis acceleration sensor element3x, the Z-axis acceleration sensor element3z, and the Y-axis acceleration sensor element3yare disposed side by side in this order from a plus side in the Y direction toward a minus side in the Y direction along the short side312. However, arrangement of the X-axis acceleration sensor element3x, the Z-axis acceleration sensor element3z, and the Y-axis acceleration sensor element3yis not limited thereto. For example, the X-axis acceleration sensor element3x, the Z-axis acceleration sensor element3z, and the Y-axis acceleration sensor element3ymay be disposed side by side in the X direction along the long sides311.

The angular velocity sensor element3ris a three-axis angular velocity sensor element for detecting angular velocities around the X axis, the Y axis, and the Z axis.

The plural internal electrodes313are disposed side by side in the X direction along the long sides311. The acceleration sensor element310and the plural internal electrodes313are disposed side by side in the Y direction along the short sides312.

The second inertial sensor32is the same as the first inertial sensor31except that the second inertial sensor32is mounted at the substrate2in a posture rotated counterclockwise by 90 degrees with respect to the first inertial sensor31when viewed from the top in the Z direction, and thus description thereof will be omitted.

Each portion located at the first surface21side of the substrate2has been described above. Next, each portion located at a second surface22side of the substrate2will be described.

As shown inFIGS.2and3, the first terminals292as the external coupling terminals of the sensor module1, and the third terminals296as the internal coupling terminals of the sensor module1are provided at the second surface22of the substrate2. The first terminals292are bonded to the lead9via the first conductive bonding members51. The third terminals296are bonded to the circuit element8via the third conductive bonding members53.

The lead9is formed by, for example, cutting a lead frame during manufacturing, and is formed of, for example, an iron-based material or a copper-based material.

The lead9includes coupling portions91bonded to the first terminals292via the first conductive bonding members51, so that the first terminals292are electrically coupled to the lead9, and the lead9is fixed to the substrate2.

In the present embodiment, the first conductive bonding member51is a lead-free solder, and a symbol indicating a composition thereof is Sn-5.0Sb. Sn-5.0Sb indicates that 5.0% of antimony (Sb) is contained with respect to elements other than tin (Sn).

Sn-5.0Sb used as the first conductive bonding member51has a melting point of 240° C. and a Young's modulus of 45.4 GPa. In other words, when Sn-5.0Sb is used as the first conductive bonding member51, the first melting point as the melting point of the first conductive bonding member51is 240° C., and the first Young's modulus as the Young's modulus of the first conductive bonding member51is 45.4 GPa.

As described above, in the present embodiment, the second melting point as the melting point of the second conductive bonding member52is 205° C., and the second Young's modulus as the Young's modulus of the second conductive bonding member52is 52.2 GPa. That is, the second conductive bonding member52has a second melting point of 205° C. lower than the first melting point of 240° C. of the first conductive bonding member51, and has a second Young's modulus of 52.2 GPa higher than the first Young's modulus of 45.4 GPa of the first conductive bonding member51.

In this manner, by setting the second Young's modulus of the second conductive bonding member52to be higher than the first Young's modulus of the first conductive bonding member51, deterioration of the second conductive bonding member52can be prevented even when a stress caused by a difference in thermal expansion coefficients of the inertial sensor3and the substrate2is repeatedly applied to the second conductive bonding member52as a bonding portion between the inertial sensor3and the substrate2. Specifically, cracks are less likely to occur in the second conductive bonding member52, and generated cracks are less likely to expand. Therefore, the inertial sensor3can be guaranteed to be electrically coupled to the substrate2for a long period of time, so that the sensor module1can be stable in function and enhanced in reliability.

In the present embodiment, although Sn-5.0Sb is used as the first conductive bonding member51, the present disclosure is not limited thereto, and a solder other than Sn-5.0Sb may be used. As the solder other than Sn-5.0Sb, for example, Sn-10.0Sb or the like can be used as the first conductive bonding member51. Sn-10.0Sb has a melting point of 245° C. and a Young's modulus of 47.9 GPa. The solder used as the first conductive bonding member51may be a solder having a melting point of 230° C. or more. Further, in the present embodiment, the lead-free solder is used as the first conductive bonding member51, but a lead-containing solder may also be used.

In addition, by using a high-temperature solder such as Sn-5.0Sb as the first conductive bonding member51, remelting of the first conductive bonding member51can be prevented when a customer is to solder the lead9to a customer substrate to mount the sensor module1at the customer substrate. The sensor module1is calibrated before delivery to the customer to correct deviation of the detection axis of the inertial sensor3, or the like, but when the first conductive bonding member51is remelted when the customer mounts the sensor module1at the customer substrate, a bonding state between the lead9and the substrate2changes. That is, the deviation of the detection axis of the inertial sensor3, or the like changes from a state before delivery, and detection accuracy of the sensor module1decreases. However, a decrease in the detection accuracy of the sensor module1can be prevented by preventing the remelting of the first conductive bonding member51.

As shown inFIGS.2and3, the second surface22of the substrate2is provided with the third terminals296. The third terminals296are bonded to the circuit element8via the third conductive bonding members53.

The circuit element8may be obtained by, for example, molding a bare chip as a semiconductor chip. The circuit element8controls driving of the inertial sensor3and processes the detection signal output from the inertial sensor3. Specifically, the circuit element8performs various processing on the detection signal output from the inertial sensor3, such as sampling, zero point correction, sensitivity adjustment, filtering, temperature correction, and detection signal synthesis, and outputs a processed detection signal.

Coupling terminals801are provided at an upper surface of the circuit element8, that is, a surface of the circuit element8facing the third terminals296. The coupling terminals801are bonded to the third terminals296via the third conductive bonding members53.

The coupling terminal801is used to input the detection signal such as the acceleration or the angular velocity detected by the inertial sensor3to the circuit element8, and to output the control signal for controlling the inertial sensor3and the processed detection signal obtained by processing the detection signal input from the inertial sensor by the circuit element8, etc. from the circuit element8.

The coupling terminals801are bonded to the third terminals296provided at the second surface22of the substrate2via the third conductive bonding members53, so that the coupling terminal801are electrically coupled to the third terminals296, and the circuit element8is fixed to the second surface22of the substrate2.

In the present embodiment, the third conductive bonding member53is formed of a lead-free solder having the same composition as that of the second conductive bonding member52. Specifically, Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni is used as the third conductive bonding member53, and has a third melting point of 205° C. as a melting point of the third conductive bonding member53, and a third Young's modulus of 52.2 GPa as a Young's modulus of the third conductive bonding member53.

As described above, in the present embodiment, the first melting point as the melting point of the first conductive bonding member51is 240° C., and the first Young's modulus as the Young's modulus of the first conductive bonding member51is 45.4 GPa. That is, the third conductive bonding member53has a second melting point of 205° C. lower than the first melting point of 240° C. of the first conductive bonding member51, and has a third Young's modulus of 52.2 GPa higher than the first Young's modulus of 45.4 GPa of the first conductive bonding member51.

In this manner, by setting the third Young's modulus of the third conductive bonding member53to be higher than the first Young's modulus of the first conductive bonding member51, deterioration of the third conductive bonding member53due to a stress caused by a difference in thermal expansion coefficients of the circuit element8and the substrate2can be prevented. Therefore, the circuit element8can be guaranteed to be electrically coupled to the substrate2for a long period of time, so that the sensor module1can be stable in function and enhanced in reliability.

In the present embodiment, although Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni is used as the second conductive bonding member52and the third conductive bonding member53, the present disclosure is not limited thereto, and a solder other than Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni may be used. Specifically, the solders used as the second conductive bonding member52and the third conductive bonding member53may be solders respectively having a second melting point and a third melting point each lower than the first melting point while having a second Young's modulus and a third Young's modulus each higher than the first Young's modulus.

Examples of the solder other than Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni include Sn-3.0Ag-3.0Bi-3.0In, Sn-3.9Ag-0.6Cu-3.0Sb, Sn-3.8Ag-0.7Cu-3.0Bi-1.4Sb-0.15Ni, and the like. Sn-3.0Ag-3.0Bi-3.0In has a melting point of 198° C. and a Young's modulus of 47.7 GPa. Sn-3.9Ag-0.6Cu-3.0Sb has a melting point of 221° C. and a Young's modulus of 50.1 GPa. Sn-3.8Ag-0.7Cu-3.0Bi-1.4Sb-0.15Ni has a melting point of 207° C. and a Young's modulus of 53.0 GPa.

Further, solders respectively having a second Young's modulus and a third Young's modulus of 50 GPa or more may be used as the second conductive bonding member52and the third conductive bonding member53. In the present embodiment, the lead-free solder is used as the second conductive bonding member52and the third conductive bonding member53, but a lead-containing solder may also be used.

In the present embodiment, the solder used for the second conductive bonding member52and the solder used for the third conductive bonding member53have the same composition, but may also have different compositions. In other words, the second melting point and the third melting point may be different from each other, and the second Young's modulus and the third Young's modulus may be different from each other. When the second melting point and the third melting point are to be set different from each other, the third melting point may be higher than the second melting point when the substrate2is to be first bonded to the circuit element8and then to the inertial sensor3; conversely, the second melting point may be higher than the third melting point when the substrate2is to be first bonded to the inertial sensor3and then to the circuit element8.

Next, a manufacturing method of the sensor module1will be described with reference toFIGS.5to9. As shown inFIG.5, the manufacturing method of the sensor module1includes a lead bonding step, a circuit element mounting step, an inertial sensor mounting step, and a lead forming step.

1.1 Lead Bonding Step

As shown inFIG.6, the first terminals292provided at the second surface22of the substrate2are bonded to the coupling portions91of the lead9via the first conductive bonding members51in step S1. A method for bonding the first terminals292and the coupling portions91of the lead9via the first conductive bonding members51may be, for example, reflow soldering.

First, the lead9and the substrate2, in which the second terminals294are provided at the first surface21while the first terminals292and the third terminals296are provided at the second surface22, are prepared. In the present embodiment, the lead9prepared in step S1is a plate-shaped lead frame having a frame body (not shown).

Next, the first conductive bonding members51are applied to the coupling portions91of the lead9. A method for applying the first conductive bonding member51can be performed by, for example, applying a paste obtained by dispersing powder of the first conductive bonding members51in a flux.

Then, in a state where the coupling portions91applied with the first conductive bonding member51and the first terminals292are brought into contact with each other via the first conductive bonding members51, the first conductive bonding members51are melted by heating in a reflow furnace. Thus, the lead9can be bonded to the first terminals292via the first conductive bonding members51.

In the present embodiment, the first conductive bonding members51are applied to the coupling portions91of the lead9, but may also be applied to the first terminals292.

1.2 Circuit Element Mounting Step

As shown inFIG.7, the third terminals296provided at the second surface22of the substrate2are bonded to the coupling terminals801provided at the circuit element8via the third conductive bonding members53in step S2. A method for bonding the third terminals296and the circuit element8via the third conductive bonding members53may be, for example, reflow soldering.

As described above, since the third conductive bonding members53have a third melting point lower than the first melting point of the first conductive bonding members51, the remelting of the first conductive bonding members51can be prevented by setting a temperature in the reflow furnace to be higher than the third melting point and lower than the first melting point in step S2. Thus, a bonding failure between the substrate2and the lead9due to the remelting of the first conductive bonding members51is less likely to occur, and a manufacturing yield of the sensor module1can be improved.

1.3 Inertial Sensor Mounting Step

As shown inFIG.8, the second terminals294provided at the first surface21of the substrate2are bonded to the coupling terminals301provided at the inertial sensor3via the second conductive bonding members52in step S3. A method for bonding the second terminals294and the inertial sensor3via the second conductive bonding members52may be, for example, reflow soldering.

As described above, since the second conductive bonding members52have a second melting point lower than the first melting point of the first conductive bonding members51, the remelting of the first conductive bonding members51can be prevented by setting the temperature in the reflow furnace to be higher than the second melting point and lower than the first melting point in step S3. Thus, a bonding failure between the substrate2and the lead due to the remelting of the first conductive bonding member51is less likely to occur, and a manufacturing yield of the sensor module1can be improved.

1.4 Lead Forming Step

As shown inFIG.9, the lead9is processed into a desired shape in step S4.

First, the frame body (not shown) of the lead frame is cut out from the lead frame, and the lead9is bent and processed into the desired shape. In the present embodiment, the lead9is processed to have a so-called gull-wing shape.

Next, the cap7is bonded to the first surface21of the substrate2via bonding members (not shown). In the present embodiment, the cap7is bonded to the substrate2after the lead9is processed into the desired shape, but the lead9may also be processed into the desired shape after the cap7is bonded to the substrate2.

The sensor module1can be manufactured by a manufacturing process described above.

As described above, according to the present embodiment, following effects can be obtained.

The sensor module1includes the first conductive bonding members51having the first melting point and the first Young's modulus, and bonding the lead9and the first terminals292provided at the substrate2, and the second conductive bonding members52having the second melting point lower than the first melting point and the second Young's modulus higher than the first Young's modulus, and bonding the inertial sensor3and the second terminals294provided at the substrate2. In this manner, by setting the second Young's modulus of the second conductive bonding members52to be higher than the first Young's modulus of the first conductive bonding members51, deterioration of the second conductive bonding members52due to the stress caused by the difference in thermal expansion coefficients of the inertial sensor3and the substrate2can be prevented. Therefore, the inertial sensor3can be guaranteed to be electrically coupled to the substrate2for a long period of time, so that the sensor module1can be stable in function and enhanced in reliability.

In addition, by setting the second melting point of the second conductive bonding member52to be lower than the first melting point of the first conductive bonding member51, when the substrate2and the lead9are first bonded by the first conductive bonding member51and then the substrate2and the inertial sensor3are bonded by the second conductive bonding member52, the remelting of the first conductive bonding member51during bonding by the second conductive bonding member52is prevented. Thus, the bonding failure between the substrate2and the lead9due to the remelting of the first conductive bonding member51is less likely to occur, and a manufacturing yield of the sensor module1can be improved.

2. Second Embodiment

Next, a sensor module1aaccording to the second embodiment will be described with reference toFIGS.10and11. In the following description, differences from the first embodiment described above will be mainly described, the same reference numerals are given to the same configuration as the first embodiment, and redundant description will be omitted.

The sensor module1aaccording to the present embodiment is different from the first embodiment in that the first surface21of the substrate2is provided with first terminals292a.

As shown inFIG.10, the first terminals292aare provided at the first surface21as the upper surface of the substrate2, and each first terminal292aand each coupling portion91aof a lead9aoverlap each other when viewed from the top in the Z direction.

As shown inFIG.11, the first terminals292aprovided at the first surface21of the substrate2are bonded to the coupling portions91aof the lead9avia first conductive bonding members51a. In the first concave portion23A of the substrate2, the lead9ahas a shape bent along a side surface and a bottom surface of the first concave portion23A. Although not illustrated, in the second concave portion23B, the third concave portion23C, and the fourth concave portion23D of the substrate2, the lead9aalso has a shape bent along side surfaces and bottom surfaces of the respective concave portions23B,23C, and23D similar to the first concave portion23A.

An insulating film93is provided at an upper surface of the lead9a, which is a surface of the lead9afacing a lower end portion of the side wall71of the cap7. By providing the insulating film93between the cap7and the lead9a, a short circuit due to contact between the cap7and the lead9acan be prevented. The insulating film93can be formed of, for example, an insulating resin such as a polyimide resin, an epoxy resin or the like. The short circuit due to contact between the cap7and the lead9amay also be prevented by separating the lower end portion of the side wall71of the cap7from the upper surface of the lead9a.

In the present embodiment, similarly to the first embodiment, Sn-5.0Sb is used as the first conductive bonding member51a, and Sn-3.0Ag-0.8Cu-3.0Bi-0.02Ni is used as the second conductive bonding member52and the third conductive bonding member53. Thus, similarly to the first embodiment, the second conductive bonding member52has a second melting point lower than a first melting point of the first conductive bonding member51aand a second Young's modulus higher than a first Young's modulus of the first conductive bonding member51a. Further, the third conductive bonding member53has a third melting point lower than the first melting point of the first conductive bonding member51aand a third Young's modulus higher than the first Young's modulus of the first conductive bonding member51a.

According to the present embodiment, even when the first terminals292aare provided at the first surface21of the substrate2, the same effects as in the first embodiment can be obtained.

Next, a sensor module1baccording to the third embodiment will be described with reference toFIGS.12and13. In the following description, differences from the first embodiment described above will be mainly described, the same reference numerals are given to the same configuration as the first embodiment, and redundant description will be omitted.

The sensor module1baccording to the present embodiment is different from the first embodiment in that the inertial sensor3is bonded to the substrate2via an insulating bonding member60. The present embodiment is also different from the first embodiment in that the circuit element8is bonded to the substrate2via an insulating bonding member61.

As shown inFIG.12, when viewed from the top in the Z direction, the insulating bonding member60is disposed at a central portion of the lower surface of the inertial sensor3. As shown inFIG.13, the lower surface of the inertial sensor3is bonded to the first surface21as the upper surface of the substrate2via the insulating bonding member60.

The insulating bonding member60may be formed of, for example, an adhesive made of a thermosetting resin such as an epoxy resin or a silicone resin. A glass transition temperature of the insulating bonding member60may be higher than an upper limit temperature of a temperature range for guaranteeing operation of the sensor module1b.

When the customer solders the lead9and the customer substrate in order to mount the sensor module1bat the customer substrate, the second conductive bonding members52bonding the inertial sensor3and the substrate may be remelted. When the second conductive bonding members52are remelted, a bonding state between the inertial sensor3and the substrate2changes. That is, the deviation of the detection axis of the inertial sensor3, or the like changes from a state before delivery, and detection accuracy of the sensor module1bdecreases. However, by bonding the inertial sensor3and the substrate2via the insulating bonding member60, the bonding state between the inertial sensor3and the substrate2is less likely to change even when the second conductive bonding members52are remelted, so that a decrease in the detection accuracy of the sensor module1bcan be prevented.

As shown inFIG.12, when viewed from the top in the Z direction, the insulating bonding member61is disposed at a central portion of the upper surface of the circuit element8. As shown inFIG.13, the upper surface of the circuit element8is bonded to the second surface22as the lower surface of the substrate2via the insulating bonding member61. Similarly to the insulating bonding member60, the insulating bonding member61may be formed of an adhesive made of a thermosetting resin such as an epoxy resin or a silicone resin.

As a method for bonding the substrate2to the inertial sensor3and the circuit element8via the insulating bonding members60and61, for example, the substrate2is bonded to the inertial sensor3and the circuit element8via the second conductive bonding members52and the third conductive bonding members53respectively, and then the insulating bonding members60and61in an uncured state can be injected into a gap between the first surface21of the substrate2and the lower surface of the inertial sensor3and a gap between the second surface22of the substrate2and the upper surface of the circuit element8respectively, and the insulating bonding members60and61after injection can be then thermally cured. However, in this manner, bonding by the second conductive bonding members52and bonding by the insulating bonding member60may be performed simultaneously, while bonding by the third conductive bonding member53and bonding by the insulating bonding member61may be performed simultaneously, instead of separately performing bonding by the second conductive bonding member52and the third conductive bonding member53, and bonding by the insulating bonding members60and61.

According to the present embodiment, following effects can be obtained in addition to the effects of the first embodiment.

When the customer mounts the sensor module1bat the customer substrate by bonding the inertial sensor3and the substrate2via the insulating bonding member60, the bonding state between the inertial sensor3and the substrate2is less likely to change even when the second conductive bonding members52are remelted, so that a decrease in the detection accuracy of the sensor module1bcan be prevented.

The sensor modules1,1a, and1bcan be applied to, for example, vehicles such as a construction machine and an agricultural machine, moving objects such as a robot and a drone, and electronic devices such as a smartphone and a head-mounted display.