JP6909354B2 - Physical quantity measuring device - Google Patents

Description

The present invention relates to a physical quantity measuring device that measures a physical quantity such as pressure.

The physical quantity measuring device refers to, for example, a pressure sensor, a torque sensor, a load sensor, a thrust sensor, etc. mounted on a vehicle or the like, and is configured by mounting a semiconductor element made of silicon or silicon carbide to form an engine fuel pressure. It is used to measure brake pressure, various gas pressures, load pressures, etc.

In a conventional pressure sensor, a semiconductor element is usually mounted on a metal diaphragm. As the material of this diaphragm, an Fe—Ni alloy having a coefficient of thermal expansion close to that of silicon may be used, but it is required to use a stainless steel diaphragm from the viewpoint of proof stress and corrosiveness.

Further, regarding the bonding between the semiconductor element and the diaphragm, it is desirable to use a brittle material such as glass or directly bond the semiconductor element and the diaphragm. This is because when joining with a general resin, solder, or the like, creep of the joining layer becomes a problem and the physical quantity measured on the semiconductor element changes. However, since stainless steel and semiconductor elements have significantly different coefficients of thermal expansion, a large thermal stress is generated in the bonding layer in the cooling step after heating and bonding. Since the bonding layer and the semiconductor element are damaged by this thermal stress, there is a problem of how to relax the thermal stress applied at the time of bonding for bonding.
In order to solve the above problem, for example, Patent Document 1 discloses that a stress absorbing material whose main component is inorganic glass is provided in an annular shape on a portion of a bonding member located on the outer peripheral side of a semiconductor element.

JP 2013-234955

However, in the method of Patent Document 1, tensile stress that lowers the reliability is generated in the joint layer located below the inner peripheral portion of the stress absorbing material provided in the annular shape. Further, in the bonding between the semiconductor element and the diaphragm, the part where the thermal stress is the largest is the bonding layer portion around the lower part of the semiconductor element and the end portion (side surface) of the bonding layer, and a stress absorber can be formed in this portion. Since the thermal stress cannot be completely absorbed, there is a problem in the reliability of the joint portion.

The physical quantity measuring device according to the present invention is a physical quantity measuring device having a semiconductor element, a base, and a bonding layer connecting the semiconductor element and the base, and at least a part of the side surface of the bonding layer relaxes stress. It is characterized in that the bonding layer is in contact with a material and has at least two or more layers and is composed of a brittle material .

According to the present invention, the thermal stress of the physical quantity measuring device can be sufficiently relaxed, and a device having high reliability in the long term can be provided.

It is sectional drawing of the pressure measuring apparatus. It is a circuit diagram of a pressure measuring device. It is sectional drawing of the joint body. It is sectional drawing of the joint body. It is sectional drawing of the joint body. It is a top view of the joined body. It is a figure which shows the analysis value and the measured value based on the type of a stress relaxation material and the like. It is a graph which shows the analysis value based on the type of a stress relaxation material and the like.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 8. The present invention is not particularly limited as long as it is a physical quantity detected by using a semiconductor element, but a pressure measuring device will be described below as an example of the physical quantity to be detected.

(Pressure measuring device)
FIG. 1 is a cross-sectional view of the pressure measuring device 100.
The pressure measuring device 100 is electrically connected to a metal housing 10 in which a pressure port 11, a base 14, and a flange 13 are formed, a semiconductor element 15 for measuring the pressure in the pressure port 11, and the semiconductor element 15. The substrate 16 is provided with a cover 18, and a connector 19 for electrically connecting to the outside.

The pressure port 11 is provided on a hollow tubular pressure introduction portion 12ha in which a pressure introduction port 12a is formed on one end side in the axial direction (lower side in the drawing) and on the other end side (upper side in the drawing) of the pressure introduction portion 12ha in the axial direction. It includes a formed cylindrical flange 13. At the central portion of the flange 13, a base 14 that is deformed by pressure and causes distortion is erected.

The base 14 has a pressure receiving surface that receives the pressure introduced from the pressure introduction port 12a, and a sensor mounting surface on a surface opposite to the pressure receiving surface.

The tip portion 12hat of the pressure introduction portion 12ha of the pressure port 11 facing the semiconductor element 15 on the base 14 side has a rectangular shape, and is the central portion of the flange 13 and slightly lower than the upper surface of the base 14. It is continuously drilled up to the site. Due to the rectangular shape of the tip portion 12 hat, a distortion difference in the x-direction-y direction is generated in the base 14.

The semiconductor element 15 is bonded to a substantially central portion on the sensor mounting surface of the base 14 via a bonding layer described later. The semiconductor element 15 is configured as a semiconductor chip including one or more strain resistance bridges 30a to 30c that output an electric signal corresponding to the deformation (distortion) of the base 14 on the silicon chip.

The substrate 16 includes an amplifier that amplifies each detection signal output from the semiconductor element 15, an AD converter that converts the analog output signal of the amplifier into a digital signal, and a digital that performs a correction calculation described later based on the digital signal. It is equipped with a signal arithmetic processing circuit, a memory in which various data are stored, a capacitor 17, and the like.

A predetermined diameter range from the center of the closing plate 18a that closes the other end in the axial direction of the cover 18 is cut out, and the cutout portion is formed of, for example, resin or the like, and the detected pressure detected by the pressure measuring device 100. A connector 19 for outputting the value to the outside is inserted.

One end of the connector 19 is fixed to the cover 18 in the cover 18, and the other end of the connector 19 is exposed to the outside from the cover 18.

Inside the connector 19, for example, a rod-shaped terminal 20 inserted by insert molding is provided. The terminal 20 is composed of, for example, three terminals, one for power supply, one for grounding, and one for signal output. One end of each terminal 20 is connected to a board 16, and the other end is connected to an external connector (not shown). , It is electrically connected to the ECU of an automobile via a wiring member.

FIG. 2 is a circuit diagram of the pressure measuring device 100. A plurality of strain resistance bridges of the semiconductor element 15 and each circuit component mounted on the substrate 16 are shown.
The strain resistance bridges 30a to 30c are configured by bridging resistance gauges whose resistance values change by being distorted according to the deformation of the base 14. Power is supplied to the strain resistance bridges 30a to 30c from the voltage source 35.

The output signals (bridge signals corresponding to pressure) of the distortion resistance bridges 30a to 30c are amplified by the amplifiers (AMP) 31a to 31c, and the amplified output signals are amplified by the amplifiers (AMP) 31a to 31c, and the amplified output signals are amplified by the AD (analog-digital) converter (ADC) 32a to. It is converted into a digital signal by 32c.

Based on the output signals of the AD converters 32a to 32c, the digital signal arithmetic processing circuit (Digital Signal Processor) 33 uses, for example, the pressure value detected by one distortion resistance bridge 30a as the other distortion resistance bridges 30b, 30c. Performs arithmetic processing to be corrected by the detected pressure value of, and outputs the corrected pressure value as a detected value of the pressure measuring device. A non-volatile memory 34 is connected to the digital signal arithmetic processing circuit 33.

The digital signal arithmetic processing circuit 33 is not limited to the correction arithmetic processing, but is a specification for comparing the detected pressure values of a plurality of strain resistance bridges and storing the detected pressure values of the strain resistance bridges in the non-volatile memory 34 in advance. By comparing with the pressure value, deterioration of the device to be measured and deterioration of the semiconductor element 15 are determined, and processing such as outputting a failure signal at the time of the determination is also performed.

The supply of electric power from the voltage source 35 to the distortion resistor bridges 30a to 30c and the output of each signal from the digital signal arithmetic processing circuit 33 are performed via the terminal 20 of FIG.

The non-volatile memory 34 may be mounted on a circuit chip different from the circuit components mounted on the substrate 16. Further, the correction calculation may be performed by an analog circuit instead of the digital signal calculation processing circuit 33.

(Joint part between semiconductor element and base)
3 to 5 are examples showing a cross section of a joint body of the semiconductor element 15, the bonding layer 21, and the base 14.

As shown in FIG. 3, the base 14 and the semiconductor element 15 are joined via a bonding layer 21. In this example, the entire side surface of the joint layer 21 is covered with the stress relaxation material 22. In addition, at least a part of the side surface of the joint layer 21 may be in contact with the stress relaxation material 22. Here, the side surface of the bonding layer 21 refers to a surface located in the direction perpendicular to the mounting surface of the base 14 when the semiconductor element 15 is viewed from the base 14. The stress relaxation material 22 that comes into contact with at least a part of the side surface of the joint layer 21 relaxes the thermal stress generated by the difference in the coefficient of thermal expansion between the semiconductor element 15 and the base 14, thereby improving the reliability of the joint. ..

As shown in FIGS. 4 and 5, the bonding layer 21 does not need to be composed of one layer, and may be divided into a plurality of layers. When the semiconductor element 15 is divided into a plurality of layers, for example, as shown in FIG. 4, a bonding layer 21a having a role of bonding the semiconductor element 15 below the heat resistant temperature of the semiconductor element 15 and a high Young's modulus and high insulation property are provided. It can be configured by sharing roles such as the bonding layer 21b having. In this case, the bonding layer 21a does not have to be insulating. The bonding layer divided into a plurality of layers is at least two layers or more, and may be composed of a brittle material. The bonding layer has at least one or more insulating layers.

Further, as shown in FIG. 5, in addition to the bonding layer 21a and the bonding layer 21b, a bonding layer 21c having a role of bonding to the base 14 may be added. By forming the plurality of layers as shown in FIGS. 4 and 5, the thermal stress generated in the bonding layer 21 can be well dispersed, so that the reliability of the bonding can be further improved. It is desirable that the bonding layer 21 is made of a lead-free material in consideration of the environment. Lead-free in the present embodiment means that it is permitted to contain prohibited substances in the range of the specified value or less in the RoHS Directive (Restriction of Hazardous Substations: enforced on July 1, 2006). The thickness of the bonding layer 21 is not particularly specified and can be widely used from about 5 to 500 μm, but is particularly preferably 20 μm or more and 300 μm or less in terms of reliability and output as a sensor.

Further, FIG. 6 is a top view of the joined body. This is an example of a case where the bonded body of the semiconductor element 15, the bonding layer 21, and the base 14 shown in FIGS. 3 to 5 is observed from above. In this example, the entire joint layer 21 is covered with the stress relaxation material 22 around the joint layer 21. In FIG. 6, the entire side surface of the joint layer 21 is covered with the stress relaxation material 22, but a part of the side surface of the joint layer 21 may come into contact with the stress relaxation material 22.

In this way, at least a part of the side surface of the joint layer 21 is in contact with the stress relaxation material 22, and more preferably, as shown in FIGS. 3 to 5, the entire side surface of the joint layer 21 is covered. It is in a state of being. More preferably, as shown in FIG. 6, the entire joint layer 21 is covered with the stress relaxation material 22. By covering the joint layer 21 with the stress relaxation material 22, the thermal shrinkage of the joint layer 21 is relaxed by a tensile force. Further, at least a part of the side surface of the semiconductor element 15 is in contact with the stress relaxation material 22. As a result, the thermal stress generated in the semiconductor element 15 can be relaxed.

The material of the semiconductor element 15 is not particularly limited, but silicon or silicon carbide, which are general materials, can be used. At this time, a thin film layer can be formed on the back surface of the semiconductor element 15 in order to improve the adhesive strength with the bonding layer 21 and alleviate the thermal stress at the time of bonding. It is desirable that the thin film layer contains at least Al, Ni, Ti, Mo, Ag, and SiN. As a result, even if the material of the semiconductor element 15 is changed, it is possible to join the semiconductor element 15 according to the bonding layer 21.

The material of the base 14 is required to have a high yield strength so as to be able to cope with high pressure and repeated stress, and to have a low thermal expansion characteristic in order to reduce the difference in the coefficient of thermal expansion from the semiconductor element 15. Therefore, for example, in the SUS system, SUS630, SUS430, SUS420J2 and the like are adopted. Further, in the iron system, cast iron, chrome molybdenum steel, carbon tool steel and the like can be used. When an iron-based material is used, it may be subjected to a treatment such as plating in order to improve the corrosion resistance. The type of plating is not particularly limited, but zinc-nickel alloy plating or the like can be applied. The proof stress of the base 14 is preferably 400 MPa (megapascal) or more. In the case of less than this, the reliability of the base 14 is lowered due to the repeated stress generated in the base 14. The coefficient of thermal expansion of the base 14 ^{is preferably 140 × 10 -7} / ° C. or less. In the case of more than this, it becomes difficult to relax the thermal stress in the bonding layer 21 due to the large difference in the coefficient of thermal expansion from the semiconductor element 15, and the reliability is lowered. Here, the coefficient of thermal expansion in the present embodiment refers to a value measured in a temperature range of room temperature to 250 ° C.

The bonding layer 21 is not particularly limited as long as it has insulating properties and low creep characteristics, and a resin material can also be used, but from the viewpoint of low creep characteristics, a brittle material such as glass is included. Is preferable. The reason why insulation is required is that noise applied from the base 14 to the semiconductor element 15 at the time of mounting on an automobile or the like can be suppressed, and the reason why low creep characteristics are required is to the semiconductor element 15 for measuring a physical quantity. This is because the physical quantity does not change. Here, the insulating property in the present embodiment means that the volume resistivity is 10 ¹⁰ Ωcm or more.

From the viewpoint of thermal stress relaxation, the coefficient of thermal expansion (α _{21 ) of the bonding layer 21 is preferably equal to or greater than the coefficient of thermal expansion (α 15} ) of the semiconductor element 15 and less than or equal to the coefficient of thermal expansion (α _{14) of the base 14.} That is, the relationship of _{α 14} ≧ α ₂₁ ≧ α _{15 is satisfied.} Further, when the bonding layer is a plurality of layers as described above, if the coefficient of thermal expansion of each layer is α _21a, α _21b, α _21c ... In order from the top of the layer, then α ₁₄ ≧ ... α _21c. It is preferable to satisfy the relationship of ≧ α _21b ≧ α _21a ≧ α _15.

The stress relaxation material 22 is not particularly limited as long as it does not react with the semiconductor element 15, the bonding layer 21, and the base 14, but it is desirable that the stress relaxation material 22 includes a ductile material such as a resin material. When it is formed only of a brittle material such as low melting point glass, the stress relaxation material 22 itself may be damaged by the stress generated in the stress relaxation material 22. In that case, since it may cause damage to the bonding layer 21 and the semiconductor element 15, it is desirable that the bonding layer 21 and the semiconductor element 15 are made of a material containing a ductile material such as a resin material from the viewpoint of reliability. Further, as the stress relaxation material 22, a protective member that protects the circuit on the substrate 16 may be used.

Further, in the case of lead-free low melting point glass, a glass composition containing vanadium is selected as a glass composition that can be bonded below the heat resistant temperature of the semiconductor element 15. In this case, the side surface of the bonding layer 21 is formed by a stress relaxation material 22. Insulation cannot be guaranteed when coated. From the same viewpoint, the stress relaxation material 22 is required to have an insulating property. Further, the merit of including the resin material is that the resin material can be formed at a temperature lower than the bonding temperature of the bonding layer 21, so that the reaction with the bonding layer 21 can be suppressed. That is, the bonding temperature of the bonding layer is equal to or lower than the heat resistant temperature of the semiconductor element. As a result, a stress relaxation material can be formed on the side surface of the joint layer 21 and the side surface of the semiconductor element 15 where the thermal stress becomes large, and the thermal stress generated in the joint layer 21 and the semiconductor element 15 can be effectively relaxed. Can be done.

It is desirable that the coefficient of thermal expansion (α ₂₂ ) of the stress relaxation material 22 is equal to or less than the coefficient of thermal expansion (α _{14) of the base 14.} More preferably, it is equal to or higher than the _{coefficient of thermal expansion (α 21) of the bonding layer 21.} That is, it is desirable to satisfy the relationship of _{α 14} ≧ α _22. More preferably, α ₁₄ ≧ α ₂₂ ≧ α ₂₁ . By setting the coefficient of thermal expansion within the above range, the thermal stress generated at the time of joining can be effectively relaxed.

The Young's modulus of the stress relaxation material 22 is preferably 1.9 GPa or more. More preferably, it is 3.9 GPa or more. When this is satisfied, the thermal stress generated at the time of joining can be effectively relaxed.

The resin material contained in the stress relaxation material 22 may be either crystalline or amorphous, and may be used in combination of several types instead of one type. Examples of the resin material include polyethylene, polyvinyl chloride, polypropylene, polystyrene, polyvinyl acetate, ABS resin, AS resin, acrylic resin, polyacetal resin, polyimide, polycarbonate, modified polyphenylene ether (PPE), polybutylene terephthalate (PBT), and the like. Polyarylate, polysulfone, polyphenylene sulfide, polyether ether ketone, polyimide resin, fluororesin, polyamideimide, polyether ether ketone, epoxy resin, phenol resin, polyester, polyvinyl ester and the like can be used. Further, as the rubber, resins such as fluororubber, silicone rubber, and acrylic rubber can be used. However, from the viewpoint of heat resistance, the glass transition temperature is preferably 130 ° C. or higher. At temperatures lower than this, there is a possibility that the sensor characteristics will change due to resin deterioration due to the external temperature.

The member included in the stress relaxation material 22 may include a filler material such as ceramics in order to adjust the coefficient of thermal expansion and Young's modulus in addition to the resin material. Examples of the filler material include wollastonite, potassium titanate, zonotrite, gypsum fiber, aluminum borate, aramid fiber, fibrous magnesium compound, carbon fiber, glass fiber, talc, mica, glass flakes, polyoxyvedin zoyl whisker and the like. Can be used. Further, a plurality of these can be used in combination.

The above resin material and filler material can be used in combination to obtain a preferable coefficient of thermal expansion and Young's modulus. Further, the stress relaxation material 22 can be used as a common member for joining / sealing other members when forming the physical quantity measuring device. In that case, since the number of steps can be reduced, it is possible to select the resin material and the filler material from that viewpoint.

(Example 1-3, Comparative Example 1)
Hereinafter, the measured values based on the type of stress relaxation material and the like will be described with reference to examples. However, the present invention is not limited to the description of the examples taken up here, and may be combined as appropriate.

Examples 1 to 3 shown in FIG. 7 (A) are examples when the type of stress relaxation material is changed from material A to material C, and a comparative example shows a case where the stress relaxation material is not used. In these examples, in the bonding structure shown in FIG. 5, the thermal stress generated at the bonding surface of the semiconductor element 15 with the bonding layer 21a when a temperature change of 130 ° C. to −40 ° C. is applied is analyzed by CAE. Is. In Example 1, the coefficient of thermal expansion α (× ppm / ° C.) was 10, Young's modulus (GPa) was 22.8, and the maximum principal stress change rate (%) applied to the semiconductor element 15 was 29. In Example 2, the coefficient of thermal expansion α (× ppm / ° C.) was 41, Young's modulus (GPa) was 3.9, and the principal stress change rate (%) was 37. In Example 3, the coefficient of thermal expansion α (× ppm / ° C.) was 89, Young's modulus (GPa) was 1.9, and the principal stress change rate (%) was 92.

FIG. 8 (A) is a graph in which the coefficient of thermal expansion is plotted on the horizontal axis and the rate of change in principal stress is plotted on the vertical axis for Examples 1 to 3 shown in FIG. 7 (A). FIG. 8B is a graph in which Young's modulus is plotted on the horizontal axis and principal stress change rate is plotted on the vertical axis for Examples 1 to 3 shown in FIG. 7A.

Note that FIG. 7B shows the semiconductor element 15, the bonding layer 21a, the bonding layer 21b, the bonding layer 21c, and the base used in the analysis of Examples 1 to 3 shown in FIG. 7 (A). It shows 14 physical property values. The coefficient of thermal expansion α (× ppm / ° C.) is 3.0, 6.0, 7.2, 11.6, respectively, in the order of the semiconductor element 15, the bonding layer 21a, the bonding layer 21b, the bonding layer 21c, and the base 14. 11.3. The Young's modulus (GPa) is 170, 53, 73, 53, 205, respectively, in the order of the semiconductor element 15, the bonding layer 21a, the bonding layer 21b, the bonding layer 21c, and the base 14.

From FIGS. 7 (A), 8 (A), and 8 (B), it was found that the thermal stress can be reduced by forming the stress relaxation material 22 as shown in FIG. Further, from FIGS. 7 (B) and 8 (A), in order to effectively reduce the thermal stress, the effect is large when the coefficient of thermal expansion of the stress relaxation material 22 is equal to or less than the coefficient of thermal expansion of the base 14. It turned out to be. Further, from FIGS. 7 (A) and 8 (B), the effect was greater when the Young's modulus of the stress relaxation material 22 was 1.9 GPa or more, and more effective was 3.9 GPa or more.

(Example 4-6, Comparative Example 2)
In this example, the reliability of the joint structure shown in FIG. 5 was examined experimentally.
<Making of joint material>
In producing the bonding material, a glass plate (D263 manufactured by SCHOTT) was used for the bonding layer 21b. The bonding layers 21a and 21c forming paste were applied to the upper and lower sides of the glass plate by screen printing, dried at 150 ° C. for 30 minutes, and then calcined to obtain a bonding material. The bonding layer 21a is V ₂ O _5- P ₂ O _5- TeO _2- Fe ₂ O ₃ glass (coefficient of thermal expansion α = 6.0 ppm / ° C.), and the bonding layer 21c is V ₂ O ₅ −. P ₂ O _5- TeO _2- BaO-K ₂ O-based glass (coefficient of thermal expansion α = 11.6 ppm / ° C.) was used.

<Prototype of joint>
As the material to be joined, a semiconductor element 15 (160 μm thickness) having metallized Ti and Al on the back surface and a base 14 made of SUS630 were used. The bonding layer 21 produced as described above was placed between the semiconductor element 15 and the base 14, and a load was applied from the upper surface of the semiconductor element 15 and heated to produce a bonded body. At this time, the heating conditions were maintained at 400 ° C. for 10 minutes.

<Formation of stress relaxation material 22>
As the stress relaxation material 22, the materials A, B, and C described in Examples 1 to 3 were used to hold the stress relaxation material 22 at 100 to 160 ° C. for 1 to 2 hours.

<Evaluation of joining reliability>
A four-point bending test was carried out to evaluate the reliability of the joint. In the 4-point bending test, the joint strength was measured by measuring the stress at the time of breaking the joint. The result is shown in FIG. 7 (C).

Examples 4 to 6 shown in FIG. 7C are examples when the type of stress relaxation material is changed from material A to material C, and a comparative example shows a case where the stress relaxation material is not used. In Example 4, the average bonding strength was 198 and the Weibull coefficient m was 5.1. In Example 5, the average bonding strength was 157 and the Weibull coefficient m was 6.6. In Example 6, the average bonding strength was 109 and the Weibull coefficient m was 4.5. In the comparative example in which the stress relaxation material is not used, the average joint strength is 100 and the Weibull coefficient m is 3.0. The average bonding strength (MPa) is the average stress when the bonded body breaks. From the above results, it was confirmed that in the joint structure shown in FIG. 5, the joint strength of the joint is actually improved by forming the stress relaxation material 22. It was also found that the Weibull coefficient, which indicates the variation in bonding strength, can be improved.

(Example 7, Comparative Example 3)
In this example, an example in which the reliability of the joint structure shown in FIG. 4 is tested will be described.
As the bonding layer 21a forming paste, the same paste as in Example 4-6 was used. The bonding layer 21b was formed by using the bonding layer 21b forming paste. Bonding layer 21b forming paste _was used SiO ₂ -Al ₂ O 3 -BaO based glass paste (thermal expansion coefficient α = 7.1ppm / ℃). The bonding layer 21b was formed by printing the bonding layer 21b forming paste on the base using screen printing, drying at 150 ° C. for 30 minutes, and firing at 850 ° C. for 10 minutes to form a bonding layer 21b of about 20 μm. .. The bonding layer 21a forming paste prepared in Example 4-6 is similarly applied to the upper surface of the bonding layer 21b by screen printing, and temporarily fired by holding at 400 ° C. for 30 minutes to carry out a temporary firing to obtain a bonding layer of about 20 μm. 21a was formed. Then, the semiconductor element 15 was placed on the upper surface of the bonding layer 21a in the same manner as in Example 4-6, a load was applied, and the bonding was held at 400 ° C. for 10 minutes to prepare a bonded body. The stress relaxation material 22 used in Example 4 was formed in the same manner on the produced bonded body. Further, as Comparative Example 3, a material that does not form the stress relaxation material 22 was also produced.

A four-point bending test was carried out on the prepared joint body in the same manner as in Example 4-6. As a result, it was found that the joint strength could be improved and the variation could be reduced as in Example 4-6. From the above results, it was found that the present invention has an effect of relaxing the thermal stress generated at the time of joining regardless of the structure of the joining layer 21.

(Example 8-10, Comparative Example 4)
In this example, an example in which the reliability of the pressure sensor shown in FIG. 1 is examined will be described. The joining structure was the same as in Example 4. However, as for the form of the stress relaxation material 22, as shown in FIG. 7 (D), in Example 8, a part of the side surface of the joint layer is covered, and in Example 9, the entire side surface of the joint layer is covered. In Example 10, the entire bonding layer and the entire side surface of the semiconductor element (corresponding to FIG. 6) were produced. Further, as Comparative Example 4, a material that does not form the stress relaxation material 22 was also produced.

For the produced pressure sensor, the pressure range of 0 to 20 MPa was set to 0.5 to 4.5 V at full scale (FS), and the following reliability test was carried out. The thermal shock shown in FIG. 7 (D) is a reliability test of 2000 cycles of the thermal shock test at 130 ° C. to −40 ° C. The -40 ° C. standing shown in FIG. 7D is an evaluation of the drift characteristics of the sensor output value by a 2000-hour standing test at −40 ° C. The 130 ° C. standing shown in FIG. 7D is an evaluation of the drift characteristics of the sensor output value by a 2000 hour standing test at 130 ° C. The evaluation result shows that the change in the output value at 20 ° C. before and after the test is 2% F. S. Less than 2% and 3% F. S. Less than good, 3% or more and less than 4% F. S. The thing was allowed. However, if there was something that could not be evaluated due to cracks, etc., it was not possible. As a result, as shown in FIG. 7 (D), Example 10 showed the best reliability, and Examples 9 and 8 also showed good reliability.

From the above results, it was confirmed that the formation of the stress relaxation material 22 also improves the long-term reliability. Here, when the entire surface of the bonding layer is covered and when only a part of the bonding layer is in contact, the change in output value tends to be smaller when the entire surface of the bonding layer is covered. Therefore, since the stress relaxation material can relax the stress of the entire joint structure, it was found that a larger covering area is desirable. Most preferably, it is preferable that the side surfaces of the semiconductor element also come into full contact with each other.

According to the embodiment described above, the following effects can be obtained.
(1) The physical quantity measuring device 100 includes a semiconductor element 15, a base 14, and a bonding layer 21 that connects the semiconductor element 15 and the base 14, and at least a part of the side surface of the bonding layer 21 is stressed. It is characterized in that it is in contact with the relaxation material 22. As a result, the thermal stress of the physical quantity measuring device 100 can be sufficiently relaxed, and a device with high reliability in the long term can be provided.

The present invention is not limited to the above-described embodiment, and other embodiments that can be considered within the scope of the technical idea of the present invention are also included within the scope of the present invention as long as the features of the present invention are not impaired. .. Further, the configuration may be a combination of the above-described embodiments.

10 ... Metal housing 11 ... Pressure port 12 ... Pressure introduction part 12a ... Pressure introduction port 12ha ... Pressure introduction part 12hat ... Tip part 13 ... Flange 14 ... Base 15 ... Semiconductor element 16 ... Board 17 ... Capacitor 18 ... Cover 18a ... Closure plate 19 ... Connector 20 ... Terminal 21, 21a-21c ... Bonding layer 22 ... Stress relief material 30a-30c ... Strain resistance bridge 31a-31c ... Amplifier 32a-32c ... AD converter 33 ... Digital signal arithmetic processing circuit 34 … Non-volatile memory 35… Voltage source 100… Pressure measuring device

Claims (14)

In a physical quantity measuring device having a semiconductor element, a base, and a bonding layer connecting the semiconductor element and the base, at least a part of the side surface of the bonding layer comes into contact with the stress relaxation material .
A physical quantity measuring device characterized in that the bonding layer is at least two layers and is made of a brittle material. In the physical quantity measuring device according to claim 1,
A physical quantity measuring device characterized in that the entire side surface of the joint layer is covered with the stress relaxation material. In the physical quantity measuring device according to claim 1 or 2.
A physical quantity measuring device characterized in that the entire joint layer is covered with a stress relaxation layer. In the physical quantity measuring device according to any one of claims 1 to 3.
A physical quantity measuring device characterized in that the stress relaxation material is also in contact with the side surface of the semiconductor element. In the physical quantity measuring device according to any one of claims 1 to 4.
The stress relaxation material is a physical quantity measuring device including a ductile material. In the physical quantity measuring device according to any one of claims 1 to 5.
The stress relaxation material is a physical quantity measuring device characterized by containing a resin material. In the physical quantity measuring device according to any one of claims 1 to 6.
A physical quantity measuring device characterized in that the glass transition temperature of the stress relaxation material is 130 ° C. or higher. In the physical quantity measuring device according to any one of claims 1 to 7.
A physical quantity measuring device characterized in that the Young's modulus of the stress relaxation material is 1.9 GPa or more. In the physical quantity measuring device according to any one of claims 1 to 8.
A physical quantity measuring device characterized in that the coefficient of thermal expansion of the stress relaxation material is equal to or less than the coefficient of thermal expansion of the base. In the physical quantity measuring device according to claim 9.
A physical quantity measuring device characterized in that the coefficient of thermal expansion of the stress relaxation material is equal to or less than the coefficient of thermal expansion of the base and equal to or greater than the coefficient of thermal expansion of the joint layer. In the physical quantity measuring device according to any one of claims 1 to 10.
A physical quantity measuring device characterized in that the bonding layer is composed of three layers. In the physical quantity measuring device according to any one of claims 1 to 11.
A physical quantity measuring device, wherein the bonding layer has at least one or more insulating layers. In the physical quantity measuring device according to any one of claims 1 to 12.
A physical quantity measuring device characterized in that the coefficient of thermal expansion of the bonding layer has a characteristic between the coefficient of thermal expansion of the base and the coefficient of thermal expansion of the semiconductor element or more. In the physical quantity measuring device according to any one of claims 1 to 13.
A physical quantity measuring device characterized in that the bonding temperature of the bonding layer is equal to or lower than the heat resistant temperature of the semiconductor element.

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