WO2016039019A1

WO2016039019A1 - Flow rate sensor

Info

Publication number: WO2016039019A1
Application number: PCT/JP2015/070705
Authority: WO
Inventors: 河野　務; 翼渡辺; 裕樹中土; 徳安　昇; 忍田代; 努阪本
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2014-09-09
Filing date: 2015-07-21
Publication date: 2016-03-17
Also published as: JP2017198453A

Abstract

This flow rate sensor is provided with: a semiconductor chip which has a thermal flow rate sensing part on a main surface; a supporting member which supports the semiconductor chip; an intermediate member which is interposed between the supporting member and the semiconductor chip; and a sealing resin which covers the main surface of the semiconductor chip so that the flow rate sensing part is exposed therefrom. The intermediate member is formed from a filler-containing synthetic resin wherein a filler is contained in a synthetic resin, said filler having a higher elastic modulus and a lower linear expansion coefficient than the synthetic resin.

Description

Flow sensor

The present invention relates to a flow rate sensor, and more particularly to a flow rate sensor including a semiconductor chip having a flow rate detection unit.

An internal combustion engine such as an automobile includes an electronically controlled fuel injection device for appropriately operating the internal combustion engine by appropriately adjusting the amount of air and fuel flowing into the internal combustion engine. The electronically controlled fuel injection device is provided with a flow sensor for measuring the flow rate of air flowing into the internal combustion engine.
The flow rate sensor has, for example, a thermal flow rate detection unit including a heating resistor and a resistance temperature detector. The flow rate detection unit is provided on the semiconductor chip and has a structure in which the periphery of the semiconductor chip is sealed with resin in a state where the flow rate detection unit is exposed.

The semiconductor chip is usually mounted on a lead frame in order to connect to an external device. However, stress is generated in the semiconductor chip due to the difference in coefficient of linear expansion between the lead frame and the semiconductor chip. For this reason, a flow sensor is known in which an intermediate member formed of glass is interposed between a lead frame and a semiconductor chip to reduce stress based on a difference in linear expansion coefficient (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2009-36639

If glass is used as the intermediate member, the price is high. Moreover, since glass has a large thermal conductivity, it adversely affects the detection of the flow rate.

According to the first aspect of the present invention, the flow sensor is interposed between a semiconductor chip having a thermal flow rate detection unit on the main surface, a support member that supports the semiconductor chip, and the support member and the semiconductor chip. The intermediate member, and a sealing resin that exposes the flow rate detection unit and covers the main surface of the semiconductor chip. The intermediate member has a higher elastic modulus and a linear expansion coefficient in the synthetic resin than the synthetic resin. It is formed of a filler-containing synthetic resin containing a low filler.
According to the second aspect of the present invention, the flow rate sensor is mounted on the semiconductor chip having the thermal flow rate detection part on the main surface, the support member that supports the semiconductor chip, and the semiconductor chip is the main part. An intermediate member that is bonded with an adhesive on the back surface facing the surface and formed of a material including a synthetic resin, and a sealing resin that exposes the flow rate detection unit and covers the main surface of the semiconductor chip. Is a member formed by dividing one raw resin molded body on which a plurality of intermediate members are formed.

According to the present invention, the intermediate member is inexpensive and the flow rate sensor can be made inexpensive. In addition, since the thermal conductivity is reduced, the accuracy of flow rate detection can be improved.

FIG. 1 shows an embodiment of a flow sensor according to the present invention, FIG. 1 (a) is a plan view thereof, FIG. 1 (b) is a sectional view taken along line Ib-Ib of FIG. 1 (a), and FIG. ) Is a cross-sectional view taken along line Ic-Ic in FIG. FIG. 2 is an enlarged view showing details of FIG. 3 shows an intermediate member according to an embodiment of the present invention, FIG. 3 (a) is a plan view thereof, FIG. 3 (b) is a sectional view taken along line IIIb-IIIb of FIG. 3 (a), and FIG. ) Is a plan view of an unprocessed resin molding for explaining a method for producing an intermediate member. 4 is a view in which the sealing resin in FIG. 1 is removed, FIG. 4 (a) is a plan view thereof, and FIG. 4 (b) is a sectional view taken along line IVb-IVb of FIG. 4 (a). FIG. 5 is a cross-sectional view showing a method for molding a sealing resin. FIG. 6 is a cross-sectional view showing a second embodiment of the flow sensor according to the present invention. FIG. 7 is a cross-sectional view showing a third embodiment of the flow sensor according to the present invention. FIG. 8 is a sectional view showing a flow sensor according to a fourth embodiment of the present invention. FIG. 9 is a sectional view showing a flow sensor according to a fifth embodiment of the present invention. FIG. 10 shows a flow sensor according to a sixth embodiment of the present invention, FIG. 10 (a) is a plan view thereof, FIG. 10 (b) is a cross-sectional view taken along line Xb-Xb of FIG. 10 (a), and FIG. ) Is a cross-sectional view taken along line Xc-Xc in FIG.

Embodiment 1
<Overall structure of flow sensor>
FIG. 1 shows an embodiment of a flow sensor according to the present invention, FIG. 1 (a) is a plan view thereof, and FIG. 1 (b) is a sectional view taken along line Ib-Ib of FIG. 1 (a). FIG. 1C is a cross-sectional view taken along the line Ic-Ic in FIG. 4 is a view in which the sealing resin in FIG. 1 is removed, FIG. 4 (a) is a plan view thereof, and FIG. 4 (b) is a sectional view taken along line IVb-IVb of FIG. 4 (a). .
The flow sensor 100 is installed, for example, in an intake duct of an internal combustion engine of a vehicle. The flow sensor 100 is a thermal air flow sensor.
In the following description, the X direction, the Y direction, and the Z direction are as illustrated.

The flow sensor 100 includes a lead frame 20 having a plurality of leads 21, an intermediate member 50 mounted on the lead frame 20, a first semiconductor chip 30 and a second semiconductor mounted on a chip mounting portion 50 c of the intermediate member 50. A chip 40 and a sealing resin 60 that seals the first semiconductor chip 30 and the second semiconductor chip 40 together with the lead frame 20 by exposing the leads 21 of the lead frame 20 and a part of the first semiconductor chip 30 are provided. Yes. The intermediate member 50 is bonded to the lead frame 20 with an adhesive 71. The first semiconductor chip 30 is bonded to the intermediate member 50 with an adhesive 72 provided annularly at the peripheral edge. The second semiconductor chip 40 is bonded to the intermediate member 50 with an adhesive 73.

The lead frame 20 is formed of, for example, a metal member such as copper, and is provided inside the dam bar 22 and a dam bar 22 formed in a rectangular frame shape as illustrated in FIG. The intermediate member mounting portion 23 on which the intermediate member 50 on which the first semiconductor chip 30 and the second semiconductor chip 40 are mounted is disposed, and a plurality of leads 21. Each lead 21 and the intermediate member mounting portion 23 are connected to the dam bar 22 by a connecting portion 24.

The first semiconductor chip 30 has an upper surface (main surface), a back surface, and a peripheral side surface, and is disposed on the chip mounting portion 50c of the intermediate member 50 with the back surface side facing the lead frame 20 side. A flow rate detection unit 31 is formed on the upper surface of the first semiconductor chip 30. A recess 33 is formed on the back surface side of the first semiconductor chip 30, and a thin diaphragm 32 is formed on the main surface side of the first semiconductor chip 30. The recess 33 of the first semiconductor chip 30 is formed by etching using KOH, and the peripheral wall is formed in a V groove shape with an inclination angle of 54, 7 °. Although not shown, the flow rate detection unit 31 includes a heating resistor, a heater control bridge, a temperature sensor bridge, and the like. By generating heat from the heating resistor, a temperature difference occurs in the resistors constituting the temperature sensor bridge and the heater control bridge according to the gas flow direction. Since the temperature difference changes corresponding to the magnitude of the flow rate, the flow rate is measured by detecting the change in resistance value associated with this temperature change. The diaphragm 32 has a function of reducing the heat capacity of the lower part of the flow rate detection unit 31 and improving the reaction rate with respect to the temperature change of each resistor. Details of such a thermal flow sensor are disclosed in, for example, Japanese Patent Application Laid-Open No. 2012-141316.
Although not shown, a surface insulating film such as a polyimide film may be formed on the surface of the first semiconductor chip 30 for the purpose of stress buffering with the adhesive 72 to be bonded, surface protection, insulation, and the like. Good.

The second semiconductor chip 40 has an upper surface (main surface), a back surface, and a peripheral side surface. The second semiconductor chip 40 is on the chip mounting portion 50c of the intermediate member 50 together with the first semiconductor chip 30 with the back surface side facing the lead frame 20 side. Is arranged. The second semiconductor chip 40 has a CPU, an input circuit, an output circuit, a memory, and the like, and also has a control circuit unit for controlling the flow rate detection unit 31 to measure the flow rate.

As shown in FIG. 4A, a plurality of wirings 11 having one end connected to the flow rate detection unit 31 and the other end connected to the electrode pad 13 are formed on the upper surface of the first semiconductor chip 30. Yes. A plurality of electrode pads 14 and a plurality of electrode pads 15 are provided on the upper surface of the second semiconductor chip 40. The electrode pad 13 and the electrode pad 14 of the second semiconductor chip 40 are connected by a wire 16. The electrode pad 15 and the lead 21 of the second semiconductor chip 40 are connected by a wire 17. The

wires

16 and 17 are made of gold, aluminum, copper or the like, and the connection between the

electrode pads

13 and 14 and the connection between the electrode pad 15 and the lead 21 are made by a wire bonding method. As will be described later, after forming the sealing resin 60, the lead frame 20 is cut by the connecting portion 24, the leads 21 are separated from each other, and the dam bar 22 is cut off. Thus, each lead 21 becomes a terminal for external connection connected only to the corresponding electrode pad 15.

The second semiconductor chip 40 is bonded by an adhesive 73 to the upper surface of the chip mounting portion 50 c whose back surface is bonded to the lead frame 20. The adhesive 73 is formed in a solid shape with a uniform thickness as a whole.
The back surface of the first semiconductor chip 30 is bonded to the lead frame 20 by the adhesive 72 except for the recess 33 formed on the back surface of the diaphragm 32 and the region corresponding to the peripheral edge thereof. It is adhered to the upper surface of

As the adhesive 72 and the adhesive 73, for example, an adhesive including a thermosetting resin such as an epoxy resin or a polyurethane resin, or an adhesive including a thermoplastic resin such as a polyimide resin, an acrylic resin, or a fluororesin is used. can do. In addition, a thermosetting resin or a thermoplastic resin as a main component, metal fine particles such as gold, silver, copper, tin, or inorganic fine particles containing silica, glass, carbon, mica, talc, etc. as components may be dispersed. Good. By dispersing metal fine particles and inorganic fine particles in appropriate amounts, the adhesive can be made conductive or the linear expansion coefficient of the adhesive can be adjusted. Further, as the

adhesives

72 and 73, a material including a silver paste or a solder material can be used.
The

adhesives

72 and 73 may be adhesive sheets, but may be formed by application.

As shown in FIGS. 1A to 1C, the first semiconductor chip 30, the second semiconductor chip 40, the wire 16, the wire 17, and the lead frame 20 expose the leading end portion of the lead 21 of the lead frame 20. Then, it is sealed with a sealing resin 60. The sealing resin 60 is provided on the outer surface of the second semiconductor chip 40 in the longitudinal direction (Y direction) of the flow rate sensor 100 and the detection opening 61 that exposes the flow rate detection unit 31 formed on the main surface of the first semiconductor chip 30. The ventilation opening 62 is formed in the. The ventilation opening 62 communicates with a ventilation passage 51 of the lead frame 20 formed in the intermediate member 50 as described later.

The sealing resin 60 also covers the back side of the lead frame 20, and the portion of the sealing resin 60 that covers the back side of the lead frame 20 communicates with a recess 33 provided on the back side of the first semiconductor chip 30. A lower opening 63 is formed.
As the sealing resin 60, for example, a thermosetting resin such as an epoxy resin or a phenol resin, or a thermoplastic resin such as polycarbonate, polyethylene terephthalate, polyphenylene sulfide, or polybutylene terephthalate can be used. Further, metal fine particles such as gold, silver, copper and tin, or inorganic fine particles containing silica, glass, carbon, mica, talc and the like as components may be dispersed. By dispersing metal fine particles and inorganic fine particles in appropriate amounts, the sealing resin 60 can be made conductive or the linear expansion coefficient of the sealing resin 60 can be adjusted.

The intermediate member 50 is formed with a first opening 52 communicating with a recess 33 provided on the back side of the first semiconductor chip 30. The intermediate member 50 is formed with a second opening 53 that communicates with a ventilation opening 62 provided in the sealing resin 60. That is, the first opening 52 and the second opening 53 are formed near both ends in the longitudinal direction (Y direction) of the intermediate member 50. The intermediate member 50 communicates with the first opening 52 on one end side and communicates with the second opening 53 on the other end side and extends in the longitudinal direction (Y direction) of the flow sensor 100. Is formed. The ventilation passage 51 is formed in a groove shape having an opening on the lower surface facing the lead frame 20, and the opening is covered with the lead frame 20.

An adhesive 71 is provided on the back surface of the intermediate member 50 and the top surface of the lead frame 20. Therefore, the ventilation passage 51 is sealed by the lead frame 20 and the adhesive 71, and the internal space of the recess 33 provided on the back surface side of the first semiconductor chip 30 is the first opening 52 of the intermediate member 50, ventilation. It is communicated with the external space of the flow sensor 100 through the passage 51, the second opening 53, and the ventilation opening 62 of the sealing resin 60.
As the material of the adhesive 71, the same material as the adhesive 72 and the adhesive 73 can be used. The adhesive 71 can be an adhesive sheet, or can be formed by coating or resin molding.

In order to make the pressure in the external space around the flow rate detection unit 31 and the internal pressure in the concave portion 33 below the diaphragm 32 substantially uniform, the sealing resin 60 has a lower opening 63 communicating with the concave portion 33 below the diaphragm 32. Is formed. However, when the change in the gas flow rate is large, the pressure in the external space around the flow rate detection unit 31 and the external pressure in the vicinity of the lower opening 63 of the sealing resin 60 have different fluctuation widths and timings. This is a factor that reduces the accuracy of flow rate detection.
In the above embodiment, the recess 33 provided in the lower part of the diaphragm 32 of the first semiconductor chip 30 is separated from the position of the diaphragm 32 in the longitudinal direction (Y direction) by the ventilation passage 51 formed in the intermediate member 50. It communicates with a ventilation opening 62 provided at the position. Therefore, the opening 62 for ventilation can be arrange | positioned in the position where the fluctuation | variation of the flow volume of gas is small. For this reason, the pressure of the external space around the flow rate detection unit 31 and the internal pressure of the recess 33 on the back surface side of the diaphragm 32 can be made substantially the same, and the accuracy of flow rate measurement can be improved.

<Manufacturing method of flow sensor>
The outline of the manufacturing method of the flow sensor will be described.
First, as shown in FIGS. 4A and 4B, a lead frame 20 in which a plurality of leads 21 and an intermediate member mounting portion 23 are connected to a dam bar 22 by a connecting portion 24 is formed.
The intermediate member 50 is fixed to the upper surface of the intermediate member mounting portion 23 of the lead frame 20 with an adhesive 71.

Adhesives

72 and 73 are provided on the intermediate member 50 to fix the first semiconductor chip 30 and the second semiconductor chip 40, respectively. On the upper surface of the first semiconductor chip 30, a flow rate detection unit 31, a wiring 11 and an electrode pad 13 are formed in advance. In the first semiconductor chip 30, the concave portion 33 on the back surface side of the diaphragm 32 is aligned with the first opening 52 of the intermediate member 50 and fixed with an adhesive 72.
The electrode pads 13 of the first semiconductor chip 30 and the electrode pads 14 of the second semiconductor chip 40 are connected by wires 16. Further, the electrode pads 15 of the second semiconductor chip 40 and the leads 21 of the lead frame 20 are connected by wires 17. Thereby, the unsealed flow rate sensor 100p illustrated in FIGS. 4A and 4B is manufactured. At this stage, the lead 21 is not separated from the lead frame 20.

FIG. 5 is a cross-sectional view showing a method of molding the unsealed flow rate sensor 100p.
As illustrated in FIG. 5, the unsealed flow rate sensor 100 p is accommodated in the cavity 103 of the upper mold 101 and the lower mold 102. An elastic film 110 is installed on the inner surface of the upper mold 101. The elastic film 110 protects the first semiconductor chip 30 sandwiched between the upper mold 101 and the lower mold 102. Although not shown, the upper mold 101 and the lower mold 102 are provided with protrusions for forming a detection opening 61, a ventilation opening 62, and a lower opening 63.

In this state, the sealing resin material is introduced from the resin inflow portion 104 and filled in the cavity 103. At this time, the dam bar 22 of the lead frame 20 prevents the sealing resin material from leaking. The sealing resin material filled in the cavity 103 of the upper mold 101 and the lower mold 102 is cured. The cured semi-finished product is taken out from the mold, the connecting portion 24 of the lead frame 20 is cut, the dam bar 22 is separated, and the respective flow rate sensors 100 shown in FIG.

In the manufacturing method of the flow rate sensor 100, the positional deviation of the flow rate detection unit 31 fixed to the first semiconductor chip 30 can be adjusted before the sealing resin material is filled. That is, it is possible to set the flow rate detection unit 31 with respect to the sealing resin 60 at an accurate position and to reduce the variation in the position of the flow rate detection unit 31.
Therefore, the detection accuracy of the gas flow rate can be improved, and the detection accuracy of all the flow rate sensors to be manufactured can be made uniform with little variation.

<Intermediate member>
Details of the intermediate member 50 will be described.
FIG. 2 is an enlarged view showing details of FIG. 3A to 3C show an intermediate member according to an embodiment of the present invention, FIG. 3A is a plan view thereof, and FIG. 3B is a plan view of FIG. FIG. 3C is a cross-sectional view taken along the line IIIb-IIIb, and FIG. 3C is a plan view of the raw resin molded body for illustrating the method for manufacturing the intermediate member.
The intermediate member 50 is a rectangular thin plate member. As described above, the intermediate member 50 has the first opening 52 formed near one end in the longitudinal direction (Y direction) and the second opening 53 formed near the other end. The first opening 52 and the second opening 53 are connected by a ventilation passage 51.

As shown in FIG. 2, the intermediate member 50 is formed of a material in which a synthetic resin 50a is filled with a filler 50b having a higher linear expansion coefficient and a higher elastic modulus than the synthetic resin 50a. As the synthetic resin 50a, a thermosetting resin or a thermoplastic resin can be used. As the thermosetting resin, for example, a material containing an epoxy resin or a phenol resin can be used. As the thermoplastic resin, for example, a material containing polycarbonate, polyethylene terephthalate, polyphenylene sulfide, polybutylene terephthalate, acrylonitrile butadiene styrene, or the like can be used.

As the filler 50b contained in the synthetic resin 50a, a metal material containing gold, silver, copper, tin, aluminum, iron, or the like, or an inorganic material containing silica, glass, carbon, mica, talc, or the like as a component can be used. By adding a colorant to the synthetic resin 50a, conductivity may be imparted, or the linear expansion coefficient and color may be controlled.

The intermediate member 50 is manufactured by a molding method such as injection molding or transfer molding. In the case of the molding method, the intermediate member 50 having the first opening 52, the second opening 53, the ventilation passage 51 and the like can be formed without secondary processing, so that the productivity is good and the production cost is reduced. can do.

As described above, the thermal flow rate detection unit 31 is formed on the upper surface of the first semiconductor chip 30. When the thermal conductivity of the intermediate member 50 is high, the heat of the flow rate detection unit 31 is transmitted to the lead frame 20 via the intermediate member 50. That is, the heat of the flow rate detection unit 31 is radiated to the outside, and the temperature decreases, so the flow rate detection accuracy decreases.
For this reason, it is preferable that the thermal conductivity of the intermediate member 50 is about 1/10 or less of silicon constituting the first semiconductor chip 30. If the intermediate member 50 is formed of only synthetic resin, the thermal conductivity can be sufficiently reduced. However, since the linear expansion coefficient of the synthetic resin is larger than that of silicon, the stress due to the difference in the linear expansion coefficient between the intermediate member 50 and the first semiconductor chip 30 is generated in the first semiconductor chip 30 only with the synthetic resin. For this reason, the detection accuracy of the flow rate decreases.

In the above embodiment, the intermediate member 50 is formed of a material in which the filler 50b having a smaller linear expansion coefficient than the synthetic resin 50a is filled in the synthetic resin 50a. For this reason, the linear expansion coefficient of the intermediate member 50 can be brought closer to the linear expansion coefficient of the first semiconductor chip 30 than when the intermediate member 50 is formed of only synthetic resin, and the flow rate detection accuracy can be improved. The linear expansion coefficient of the intermediate member 50 is preferably about 1.5 to 5.0 times that of the first semiconductor chip 30.

Usually, the plate thickness of the lead frame 20 is about 1 mm or less, but since the intermediate member 50 is interposed between the lead frame 20 and the first semiconductor chip 30, the secondary moment of section of the flow sensor 100 is reduced. Can be bigger. That is, the intermediate member 50 can have a function of reinforcing the rigidity of the lead frame 20. Furthermore, since the intermediate member 50 formed of the synthetic resin 50a filled with the filler 50b is used, the rigidity of the flow sensor 100 can be further increased.

It is preferable to fill the synthetic resin 50a with a filler 50b having a higher elastic modulus than the synthetic resin 50a by about 30% by weight or more. By increasing the elastic modulus of the intermediate member 50, the rigidity of the flow sensor 100 can be further improved.

When producing the intermediate member 50 by a mold method, it is preferable to employ a method in which a plurality of intermediate members 50 are collectively formed as shown in FIG. In this method, one intermediate member forming substrate 50m in which the intermediate members 50 having the first opening 52, the ventilation passage 51, and the second opening 53 are two-dimensionally arranged is formed by a molding method. After the intermediate member forming substrate 50m is taken out of the mold, it is cut vertically and horizontally to form individual intermediate members 50 as indicated by a two-dot chain line. By using such a manufacturing method, the productivity of the intermediate member 50 can be improved and the production cost can be reduced.

According to the one embodiment, the following effects are obtained.
(1) An intermediate member 50 formed of synthetic resin is interposed between the first semiconductor chip 30 on which the flow rate detection unit 31 is formed and the lead frame 20 as a support member. Since the synthetic resin intermediate member 50 can be formed by a molding method, the productivity is good and the production cost can be reduced. In particular, if a method is adopted in which a plurality of intermediate members 50 are collectively molded on one intermediate member forming substrate 50m and then divided into individual intermediate members 50 after forming, productivity is further improved. be able to.

(2) The intermediate member 50 is formed of a material in which a synthetic resin 50a is filled with a filler 50b having a smaller linear expansion coefficient than the synthetic resin 50a. For this reason, the linear expansion coefficient of the intermediate member 50 can be brought close to the linear expansion coefficient of the first semiconductor chip 30 on which the thermal flow rate detection unit 31 is formed. Thereby, the stress which arises in the 1st semiconductor chip 30 resulting from the difference in a linear expansion coefficient can be reduced, and the precision of flow volume detection can be improved.

(3) The intermediate member 50 is formed of a synthetic resin 50a filled with a filler 50b having a larger elastic modulus than that of the synthetic resin 50a. For this reason, the elasticity modulus of the intermediate member 50 can be made higher than the case where it forms only with a synthetic resin. Thereby, even in the structure using the lead frame 20 with a small plate thickness, the rigidity of the flow sensor 100 can be increased.

(4) The intermediate member 50 is provided with the first opening 52, the ventilation passage 51, and the second opening 53, and the recess 33 and the sealing resin 60 provided on the back surface side of the diaphragm 32 of the first semiconductor chip 30. The ventilation opening 62 was connected. For this reason, the pressure in the external space of the flow rate detector 31 provided on the upper side of the diaphragm 32 and the internal pressure of the recess 33 on the back surface side of the diaphragm 32 can be made substantially the same, improving the accuracy of flow rate measurement. be able to.
The intermediate member 50 can employ various forms different from the above-described one embodiment. An example of another form is shown below.

Embodiment 2
FIG. 6 is a sectional view showing Embodiment 2 of the flow sensor according to the present invention.
The flow sensor 100 of the second embodiment is different from the first embodiment only in the intermediate member 50A. In the following, the differences will be described, and the others will be denoted by the same reference numerals and the description thereof will be omitted.
The intermediate member 50A of the second embodiment has a structure in which the uppermost filler 50b out of the filler 50b filled in the synthetic resin 50a protrudes from the surface of the synthetic resin 50a.

When the intermediate member 50 is manufactured by a molding method, the release agent applied to the inner surface of the mold may remain on the surface of the intermediate member 50. If the release agent adheres to the intermediate member 50, the adhesive strength between the adhesive 72 and the sealing resin 60 may be reduced and peel off. When peeling occurs, it causes a decrease in strength and corrosion due to intrusion of moisture and the like.
Therefore, in the flow sensor 100 of the second embodiment, the synthetic resin 50a on the upper surface side (Z direction side) of the intermediate member 50 is removed, and the uppermost filler 50b is protruded from the surface of the synthetic resin 50a.

An example of a method for manufacturing the flow sensor 100 with good production efficiency will be described below.
Similarly to the first embodiment, a single intermediate member forming substrate 50m in which the intermediate members 50 having the first opening 52, the ventilation passage 51, and the second opening 53 are two-dimensionally arranged is molded by a molding method. Form.
The surface layer of the synthetic resin 50a on the surface to be bonded to the adhesive 72 and the sealing resin 60 on either one of the front and back surfaces of the intermediate member forming substrate 50m is removed, and the filler 50b is protruded from the surface of the synthetic resin 50a. The removal of the surface layer of the synthetic resin 50a of the intermediate member forming substrate 50m can be performed by wet etching, dry etching, blasting or polishing.
Then, each intermediate member 50A is formed by cutting the intermediate member forming substrate 50m from which the filler 50b protrudes on one side in the vertical and horizontal directions.

In the second embodiment, the same effects as the effects (1) to (4) of the first embodiment can be obtained.
In particular, in Embodiment 2, since the filler 50b protrudes from the surface of the synthetic resin 50a and the surface area that becomes the bonding surface is increased, the adhesive strength between the adhesive 72 and the sealing resin 60 can be improved. . Further, as the filler 50b, a material having good adhesiveness with the sealing resin 60 or the adhesive 72 such as silica, talc, mica, carbon, aluminum, iron or the like can be used. The adhesive strength of can be further increased. As the adhesive strength increases, the rigidity of the flow sensor 100 increases and the reliability against corrosion and the like improves.

Embodiment 3
FIG. 7 is a cross-sectional view showing a third embodiment of the flow sensor according to the present invention.
In the intermediate member 50B of the third embodiment, among the fillers 50b filled in the synthetic resin 50a, the fillers 50b on the peripheral side surface (the surfaces on both sides in the X direction and the surfaces on both sides in the Y direction) protrude from the peripheral side surface of the synthetic resin 50a. It has the structure to do. The filler 50b does not protrude from the synthetic resin 50a on the upper and lower surfaces (surfaces on both sides in the Z direction).

In order to produce the intermediate member 50B of Embodiment 3, one intermediate member forming substrate 50m in which the intermediate members 50 are two-dimensionally arranged is formed by a molding method, and the intermediate member forming substrate 50m is vertically and horizontally formed. Cut and separate into individual intermediate members 50. Thereafter, the surface of the synthetic resin 50a on the peripheral side surface of each intermediate member 50 is removed, and the filler 50b is protruded.

Also in the third embodiment, the same effects as the effects (1) to (4) of the first embodiment described above can be obtained.
In Embodiment 3, since the filler 50b protrudes from the peripheral side surface of the synthetic resin 50a and the surface area that becomes the bonding surface is increased, the adhesive strength with the sealing resin 60 can be improved. As the adhesive strength increases, the rigidity of the flow sensor 100 increases and the reliability against corrosion and the like improves.

Embodiment 4
FIG. 8 is a sectional view showing Embodiment 4 of the flow sensor according to the present invention.
The flow sensor 100 according to the fourth embodiment is different from the other embodiments in the structure in which the first semiconductor chip 30 and the intermediate member 50 are bonded with an adhesive 72A.
In the fourth embodiment, the adhesive 72 </ b> A is provided on the entire upper surface of the intermediate member 50 except for the first opening 52 and the second opening 53 (not shown in this drawing). The width of the intermediate member 50 (the length in the X direction) is larger than the width of the first semiconductor chip 30, and the first semiconductor chip 30 is disposed inside the adhesive 72A. Therefore, the upper surface of the adhesive 72A (the surface facing the first semiconductor chip 30) is bonded to the sealing resin 60 at both side edges in the width direction (X direction). Thereby, the adhesive area between the adhesive 72A and the sealing resin 60 increases, and the adhesive strength between the adhesive 72A and the sealing resin 60 increases. As the adhesive strength increases, the rigidity of the flow sensor 100 increases and the reliability against corrosion and the like improves.
The fourth embodiment also has the same effects as the effects (1) to (4) of the first embodiment described above.

-Embodiment 5
FIG. 9 is a sectional view showing Embodiment 5 of the flow sensor according to the present invention.
The intermediate member 50A of the second embodiment illustrated in FIG. 6 has a structure in which the uppermost filler 50b protrudes from the surface of the synthetic resin 50a. In the intermediate member 50C of the fifth embodiment, the outer surface of the uppermost filler 50b is formed substantially flush with the upper surface of the synthetic resin 50a. That is, also in Embodiment 5, the uppermost filler 50b is exposed from the upper surface of the synthetic resin 50a, but the upper surface is substantially flat with the synthetic resin 50a.
Also in the fifth embodiment, the same effects as the effects (1) to (4) of the first embodiment described above are obtained.

-Sixth Embodiment-
FIG. 10 shows a flow sensor according to a sixth embodiment of the present invention, FIG. 10 (a) is a plan view thereof, FIG. 10 (b) is a cross-sectional view taken along the line Xb-Xb of FIG. 10 (c) is a cross-sectional view taken along line Xc-Xc of FIG. 10 (a).
The difference between the flow sensor 100 of the sixth embodiment and the other embodiments is the structure of the intermediate member 50D and the sealing resin 60A.
The first opening 52, the ventilation passage 51, and the second opening 53 are not formed in the intermediate member 50D. Further, the opening 62 for ventilation is not formed in the sealing resin 60A.

When the flow sensor 100 is installed in an environment where the gas flow rate fluctuation is small, the recess 33 on the back surface side of the diaphragm 32 is connected to the flow rate detector 31 via the lower opening 63 formed in the sealing resin 60A. The ventilation opening 62 is not required as long as it communicates with the outside on the opposite side. Therefore, the intermediate member 50D can be a flat thin plate member that is not processed except for cutting the outer periphery. In order to form the intermediate member 50D, the intermediate member forming substrate 50m can be formed by extrusion molding, which can reduce the mold cost and increase the efficiency of the productivity, thereby further reducing the production cost. be able to.

The flow sensor 100 of the sixth embodiment also has the same effects as the effects (1) to (3) of the first embodiment described above. Moreover, since intermediate member 50D of Embodiment 6 is not subjected to groove processing or the like, the rigidity can be increased. Therefore, even when the thin lead frame 20 is used, sufficient rigidity of the flow sensor 100 can be ensured.

In each of the above embodiments, the first semiconductor chip 30 in which the flow rate detection unit 31 is formed and the second semiconductor chip 40 having a control unit that controls the flow rate detection unit 31 may be a single semiconductor chip.

The lead frame 20 in each of the above embodiments may be a resin substrate. A connection terminal connected to the flow rate detection unit 31 may be integrally formed on the substrate, or a connection lead connected to the flow rate detection unit 31 may be embedded in the sealing resin 60 as a separate member.

It is also possible to combine the structures of the above embodiments. In particular, the intermediate member 50D that does not have the first opening 52, the ventilation passage 51, and the second opening 53 shown in the sixth embodiment can be applied to the flow sensor 100 of the first to fifth embodiments. . Moreover, it can be set as the structure which combined

intermediate member

50A, 50B, 50C suitably. In the intermediate members 50A to 50C, the filler 50b may be exposed from the synthetic resin 50a also on the surface bonded to the adhesive 71.

In the above embodiments, the sealing resin 60 covering the first and

second semiconductor chips

30 and 40 is exemplified as a structure in which the upper surface is higher than the upper surface of the flow rate detection unit 31 in the Z direction. However, the upper surface of the sealing resin 60 may be lower than the upper surface of the flow rate detection unit 31 in the Z direction. Further, the sealing resin 60 may be configured to partially expose the second semiconductor chip 40 and the lead frame 20.

In addition, the present invention can be variously modified within the scope of the invention. In short, an intermediate member is interposed between a semiconductor chip having a thermal flow rate detection unit and a support member, The semiconductor chip is covered with a sealing resin by exposing the flow rate detection unit, and the intermediate member is made of a filler-containing resin in which a filler having a higher elastic modulus and a lower linear expansion coefficient than the synthetic resin is dispersed in the synthetic resin. Any formed material may be used.

The disclosure of the following priority application is hereby incorporated by reference.
Japanese Patent Application No. 2014-183436 (filed on September 9, 2014)

20 Lead frame 21 Lead 23 Intermediate member mounting portion 30 First semiconductor chip 31 Flow rate detection portion 32 Diaphragm 33 Concave portion 40 Second semiconductor chip 50 Intermediate member 50a Synthetic resin 50b Filler 50c Chip mounting portion 50A to 50D Intermediate member 51 Ventilation passage 52 First opening 53

Second opening

60, 60A Sealing resin 61 Detection opening 62 Ventilation opening 63

Lower opening

71, 72, 73 Adhesive 72A Adhesive 100 Flow rate sensor

Claims

A semiconductor chip having a thermal flow rate detector on the main surface;
A support member for supporting the semiconductor chip;
An intermediate member interposed between the support member and the semiconductor chip;
A sealing resin that exposes the flow rate detection unit and covers the main surface of the semiconductor chip;
The intermediate member is a flow rate sensor formed of a filler-containing synthetic resin in which a filler having a higher elastic modulus and a lower linear expansion coefficient than the synthetic resin is contained in the synthetic resin.
The flow sensor according to claim 1,
Furthermore, the flow sensor provided with the adhesive agent which adhere | attaches the said semiconductor chip and the said intermediate member.
The flow sensor according to claim 2,
The intermediate member is a flow sensor in which the filler is exposed on the surface at least in a region in contact with the adhesive.
The flow sensor according to claim 2,
The intermediate member is a flow sensor in which the filler is exposed on the surface in at least a part of a region in contact with the sealing resin.
The flow sensor according to claim 3 or 4,
The flow sensor, wherein the filler of the intermediate member protrudes from the synthetic resin.
The flow sensor according to claim 1,
A flow sensor in which a diaphragm having a recess on the back surface side is formed on the main surface of the semiconductor chip, and a ventilation passage communicating with the recess on the back surface side of the diaphragm is formed in the intermediate member.
The flow sensor according to claim 6, wherein the support member is rectangular.
The ventilation passage of the intermediate member extends along the support member from a first end corresponding to the recess on the back surface side of the diaphragm to a second end outside the semiconductor chip. Flow sensor.
The flow sensor according to claim 7,
The flow passage for ventilation of the intermediate member is a groove whose side facing the support member is opened, and the groove is covered with the support member.
The flow sensor according to claim 1,
The thermal conductivity of the intermediate member is a flow sensor that is 1/10 or less of the thermal conductivity of the semiconductor chip.
The flow sensor according to claim 1,
The said intermediate member is a flow sensor which contains the said filler 30weight% or more.
The flow sensor according to claim 1,
The support member is a flow rate sensor having a thickness of 1 mm or less.
A semiconductor chip having a thermal flow rate detector on the main surface;
A support member for supporting the semiconductor chip;
An intermediate member mounted on the support member, the semiconductor chip being bonded with an adhesive on the back surface facing the main surface, and formed of a material containing a synthetic resin;
A sealing resin that exposes the flow rate detection unit and covers the main surface of the semiconductor chip;
The said intermediate member is a flow sensor which is a member formed by dividing | segmenting one raw resin molding in which the said some intermediate member was formed.
The flow sensor according to claim 12,
A flow sensor in which at least a region of the intermediate member that is bonded to the adhesive has a release agent attached to the raw resin molded body removed.
The flow sensor according to claim 12 or 13,
The intermediate member is formed of a material containing a filler having a lower linear expansion coefficient than that of the synthetic resin in the synthetic resin, and the intermediate member has at least a region where the filler is bonded to the adhesive. A flow sensor exposed on the surface.