Airflow measuring device and method for producing a resin-sealed package

Abstract

Airflow meter (20) comprising a resin-sealed packaging (300) with a ladder frame (302), an airflow measuring element (301) mounted on the ladder frame (302) and having a sensing section (402), and a sealing resin part (303) that seals the ladder frame (302) and the airflow measuring element (301) such that at least the sensing section (402) is exposed, wherein a radius of curvature ρ of an exposed section of the airflow measuring element (301) that is free from the sealing resin part (303) is 2.13 mm or less.

Description

Technical field

[0001] The present invention relates to an airflow meter that measures the flow rate of air that is drawn, for example, into an internal combustion engine of a motor vehicle. Technical background

[0002] For such an airflow meter, there is, for example, a technique described in PTL 1. Citation list for patent literature

[0003] PTL 1: JP 2013-120103 A Summary of the invention: Technical problem

[0004] In the airflow meter described in PTL 1, the coefficient of linear expansion differs between the airflow metering element and the ladder frame on which the airflow metering element is mounted. Therefore, when the airflow metering element and the ladder frame are sealed with a resin to form a resin-sealed package, stress due to the thermal contraction of the resin can act on a thin-film section. This thin-film section can deform in a direction protruding from a cavity section. When this deformation occurs in the thin-film section, accurate airflow measurement becomes difficult.

[0005] On the other hand, in a case where an intermediate element such as a glass plate or a silicon plate with a linear coefficient of expansion close to that of the airflow measuring element is provided between the airflow meter and the conductor frame to reduce the deformation of the thin-film section, the problem is that an increase in the number of components and the number of assembly steps causes an increase in the cost of the airflow meter and an increase in the thickness of the intermediate element.

[0006] The present invention was made to solve this problem, and an object of the present invention is to provide an airflow meter capable of suppressing the occurrence of deformation in a thin-film section and accurately measuring an airflow quantity in a case in which an airflow measuring element is mounted on a ladder frame to form a resin-sealed package in which the airflow measuring element and the ladder frame are sealed. Solution to the problem

[0007] An airflow meter according to the present invention comprises a resin-sealed packaging containing a ladder frame, an airflow metering element mounted on the ladder frame and having a detection section, and a sealing resin part that seals the ladder frame and the airflow metering element such that at least the detection section is exposed, wherein a radius of curvature ρ of an exposed section of the airflow metering element, which is free from the sealing resin part, is 2.13 or less. Advantageous effects of the invention

[0008] According to the present invention, it is possible to provide the airflow meter which is able to suppress the occurrence of deformation in a thin-film section and to accurately measure an airflow quantity in a case in which the airflow measuring element is mounted on the conductor frame to form the resin-sealed packaging in which the airflow measuring element and the conductor frame are sealed.

[0009] Further features relating to the present invention will become apparent from the description in this document and the accompanying drawings. Furthermore, other problems, configurations, and effects than those described above will become apparent from the description of the following embodiment. List of characters [ Fig. 1] Fig. Figure 1 is a configuration diagram of an internal combustion engine in which an airflow meter is used. [ Fig. 2] Fig. Figure 2 is a view to illustrate a configuration of the airflow meter, where Fig. 2(a) a top view, Fig. 2(b) and Fig. 2(d) Side views and Fig. 2(c) is a front view. [ Fig. 3] Fig. Figure 3 is a front view of a case. [ Fig. 4] Fig. Figure 4 is a view illustrating a configuration of a resin-sealed package, in which Fig. 4(a) is a perspective view and Fig. 4(b) a cross-sectional view along a line AA of Fig. 4(a) is. [ Fig. 5] Fig. Figure 5 is an enlarged cross-sectional view showing a magnified portion of a cross-section of the resin-sealed packaging. [ Fig. 6] Fig. 6 is an explanatory diagram to illustrate a mechanism of bending stress in the packaging, wherein Fig. 6(a) shows a cross-sectional view of an element in which a thin-film section is in a convex state, Fig. 6(b) is a cross-sectional view of the element, wherein the thin-film section is in a concave state, and Fig. 6(c) is a table showing each symbol of a calculation formula to explain the mechanism. [ Fig. 7] Fig. Figure 7 is a diagram illustrating a force acting on the element and a ladder frame due to the thermal contraction of a casting resin. [ Fig. 8] Fig. Figure 8 is a view to illustrate the amount of deformation of the thin-film section, wherein Fig. 8(a) is a view that schematically illustrates a cross-section of the resin-sealed packaging, Fig. 8(b) a perspective view of the resin-sealed packaging is, Fig. 8(c) is a view that schematically illustrates a cross-section of the thin-film section, and Fig. 8(d) is an explanatory diagram to illustrate a measurement in a vertical direction and a lateral direction of the element. [ Fig. 9] Fig. Figure 9 is a diagram showing a curve that displays the amount of deformation of the thin-film section in the vertical direction and the lateral direction of the element, a curve that shows a relationship between the amount of deformation in the lateral direction and a distance, and a curve that shows a relationship between the amount of deformation in the vertical direction and a distance. [ Fig. 10] Fig. Figure 10 is a curve that shows a relationship between a curing contraction rate of a resin and the amount of deformation, where Fig. 10(a) is a curve that shows a relationship between the curing contraction rate of the resin and the amount of deformation of the thin-film section, and Fig. 10(b) is a curve that shows a relationship between the curing contraction rate of the resin and the amount of deformation of a packaging and the amount of deformation of the thin film section. [ Fig. 11] Fig. Figure 11 is an explanatory diagram to explain the amount of deformation as a function of the curing contraction rate of the resin-sealed packaging, wherein Fig. 11(a) is a view illustrating a case where the curing contraction rate is 0.09%, and Fig. 11(b) is a view illustrating a case where the hardening contraction rate is 0.3%. [ Fig. 12] Fig. Figure 12 is an explanatory diagram to illustrate the individual items and symbols of the resin-sealed packaging and a variety of different thicknesses of the thin-film section for each item. [ Fig. 13] Fig. Figure 13 is a curve that shows the relationship between the curing contraction rate of the resin and the amount of deformation of the thin film section, a relationship between a curvature and the amount of deformation of the thin film section, a relationship between a radius of curvature and the amount of deformation of the thin film section, and a relationship between a ratio of an upper resin to a lower resin and the amount of deformation of the thin film section. [ Fig. 14] Fig. Figure 14 is an explanatory diagram to illustrate the radius of curvature of the element and the amount of deformation of the thin-film section. Description of the embodiments

[0010] A mode for carrying out the invention described below (hereinafter referred to as the embodiment) solves various problems that need to be solved in a specific product, and in particular, various problems that need to be solved when used as an airflow meter for measuring airflow quantity, and exhibits various effects. One of the various problems solved by the embodiment is the content described in the preceding section "Technical Problem," and one of the various effects achieved by the embodiment is the effect described in the section "Advantages of the Invention." The various problems solved and the various effects achieved by the embodiment are described in the following description of the embodiment.Therefore, the problems solved by the embodiment and the effects described in the following embodiment are also described for content other than the content in the section “Technical Problem” and in the section “Advantageous Effects of the Invention”.

[0011] In the following embodiment, the same reference numeral indicates the same configuration, even if the figure numbers are different, and the same function and effect are achieved. For the configuration already described, only reference numerals are given in the drawings, and the description can be omitted.

[0012] An airflow meter 20 according to the embodiment in which the airflow meter according to the present invention is used in an internal combustion engine control system 1 with electronic fuel injection is described with reference to the drawings. In the Fig. In the combustion engine control system 1 shown in Figure 1, intake air 2 is drawn in by an air filter 21 based on the operation of a combustion engine 10 with an engine cylinder 11 and an engine piston 12 and is guided via an intake manifold 22 with a main channel 22a, a throttle body 23 and an intake manifold 24 into a combustion chamber 11 of the engine cylinder. The flow rate of the intake air 2 leading to the combustion chamber is measured by the airflow meter 20 according to the invention, and fuel is supplied by a fuel injector 14 based on the measured flow rate and is fed to the combustion chamber with the intake air 2 in an air-fuel mixture.It should be noted that in the present embodiment the fuel injection valve 14 is provided in the intake manifold of the internal combustion engine and that the fuel injected into the intake manifold, which together with the intake air 2 forms the air-fuel mixture, is directed into the combustion chamber via an inlet valve 15 and burns to generate mechanical energy.

[0013] The fuel and intake air 2, which are directed into the combustion chamber, are in a mixed state and combust explosively by spark ignition from a spark plug 13 to generate mechanical energy. After combustion, the gas is directed by an exhaust valve 16 to an exhaust pipe and discharged as exhaust gas 3 from the exhaust pipe to the exterior of the vehicle. The flow rate of the intake air 2 directed into the combustion chamber is controlled by a throttle valve 25, the opening of which changes depending on the actuation of an accelerator pedal. A fuel supply quantity is controlled based on the flow rate of the intake air directed to the combustion chamber, and a driver can control the mechanical energy generated by the internal combustion engine by controlling the opening of the throttle valve 25 to regulate the flow rate of the intake air directed to the combustion chamber.

[0014] The airflow rate, temperature, humidity, and pressure of the intake air 2, which is drawn in by the air filter 21 and flows through the main channel 22a, are measured by the airflow meter 20, and a signal representing the intake air flow rate 2 is transmitted from the airflow meter 20 to a control device 4. Additionally, a signal from a throttle position sensor 26, which detects the opening degree of the throttle valve 25, is transmitted to the control device 4, as is a signal from a rotary angle sensor 17 to measure the positions and states of the engine piston 12, the intake valve 15, and the exhaust valve 16 of the internal combustion engine, and furthermore, the rotational speed of the internal combustion engine. To determine the state of the fuel-air mixture ratio from the state of the exhaust gas 3, a signal from an oxygen sensor 28 is transmitted to the control device 4.

[0015] The control device 4 calculates the fuel injection quantity and the ignition timing based on the intake air flow rate 2, as measured by the airflow meter 20, and the engine speed, as measured and measured by the rotational angle sensor 17. Based on these calculations, the fuel quantity supplied by the fuel injector 14 and the ignition timing by the spark plug 13 are controlled. The fuel injection quantity and ignition timing are further fine-tuned based on changes in temperature or throttle angle, as measured by the airflow meter 20, changes in engine speed, and the air-fuel ratio, as measured by the oxygen sensor 28.The control device 4 also controls the amount of air that bypasses the throttle valve 25 through an idle air control valve 27 in the idle operating state of the internal combustion engine, and controls the speed of the internal combustion engine in the idle operating state.

[0016] Both the fuel supply quantity, which is the main control variable of the internal combustion engine, and the ignition timing are calculated using the output of the airflow meter 20 as the primary parameter. Therefore, improving the detection accuracy of the airflow meter 20, suppressing time-dependent variations, and enhancing its reliability are crucial for improving the vehicle's control accuracy and ensuring reliability.

[0017] Especially in recent years, the demands on vehicle fuel efficiency and exhaust gas purification have increased considerably. To meet these demands, it is extremely important to improve the measurement accuracy of the intake air flow rate recorded by the airflow meter 20. Furthermore, it is also important that the airflow meter 20 maintains a high level of reliability.

[0018] The vehicle on which the airflow meter 20 is mounted is used in an environment with large temperature or humidity fluctuations. It is desirable that the airflow meter 20 take into account a response to temperature or humidity changes in the operating environment and a response to dust, contaminants, and the like.

[0019] The airflow meter 20 is mounted on an intake pipe, which is exposed to the heat generated by the combustion engine. Therefore, the heat generated by the combustion engine is transferred to the airflow meter 20 via the intake pipe. Since the airflow meter 20 measures the flow rate of the intake air 2 by transferring heat with the intake air 2, it is important to suppress the influence of external heat as much as possible.

[0020] The vehicle-mounted airflow meter 20 not only solves the problems described in the section "Technical Problem" and produces the effects described in the section "Advantages of the Invention," as described below, but also solves various problems that must be solved in a product and produces various effects when the various problems described above are adequately addressed. Specific problems to be solved and specific effects to be produced by the airflow meter 20 are described in the following description of the embodiment. <Gesamtkonfiguration des Luftstrommengenmessgeräts>

[0021] As in Fig. 1, Fig. 2(a), Fig. 2(b), Fig. 2(c) and Fig. As shown in Figure 2(d), the airflow meter 20 comprises a housing 100, a cover 200, and a chip package 300. The airflow meter 20 is used in the state in which it is inserted into the main duct 22a through a mounting hole provided in a duct wall of the intake body 22 and is attached to the intake body 22.

[0022] As in Fig. As shown in Figure 3, the housing 100 is configured, for example, by injection molding a synthetic resin material and includes a flange 111 for attaching the air flow meter 20 to the intake body 22, a connection 112 projecting from the flange 111 and exposed to the outside from the intake body 22 for electrical connection with an external device, and a measuring unit 113 extending from the flange 111 and projecting towards the center of the main channel 22a.

[0023] As in Fig. 2(b), Fig. 2(c) and Fig. As shown in Figure 2(d), the measuring unit 113 has a thin and elongated shape extending straight from the flange 111 and comprises a wide front surface 121 and a wide rear surface 122, as well as a pair of narrow side surfaces 123 and 124. The measuring unit 113 projects from the inner wall of the intake body 22 towards the center of the main channel 22a in a state in which the airflow meter 20 is attached to the intake body 22. Then the front surface 121 and the rear surface 122 are arranged parallel along the central axis of the main channel 22a, and in the narrow side surfaces 123 and 124 of the measuring unit 113, the side surface 123 on one long side of the measuring unit 113 is arranged so that it faces the upstream side of the main channel 22a, and the side surface 124 on the other short side of the measuring unit 113 is arranged so that it faces the downstream side of the main channel 22a.In a state in which the airflow meter 20 is attached to the intake body 22, the distal end section of the measuring unit 113 is defined as the lower surface 125.

[0024] In the measuring unit 113, a sub-channel inlet 131 is provided on the side surface 123, and a first outlet 132 and a second outlet 133 are provided on the side surface 124. The sub-channel inlet 131, the first outlet 132, and the second outlet 133 are provided at the distal end section of the measuring unit 113, which extends from the flange 111 in the direction of the center of the main channel 22a. Therefore, the gas can be directed into the sub-channel in the section near the central section, which is furthest from the inner wall surface of the intake body 22. Therefore, the airflow meter 20 can measure the gas flow rate in the section furthest from the inner wall surface of the intake body 22 and suppress a decrease in measurement accuracy due to the influence of heat or similar factors.

[0025] The airflow meter 20 has a shape in which the measuring unit 113 extends along the axis from the outer wall of the intake body 22 towards the center, but the widths of the side surfaces 123 and 124 are relatively narrow, as shown in Fig. 2(d) is shown. As a result, the airflow meter 20 can suppress fluid resistance with respect to the intake air 2 to a small value.

[0026] The measuring unit 113 is inserted into the intake body 22 through the mounting hole provided in the intake body 22, and the flange 111 rests against the intake body 22 and is fastened to it with a screw. The flange 111 has a shape with a predetermined plate thickness and is essentially rectangular in plan view, as shown in Fig. As shown in Figure 2(a), mounting hole sections 141 are provided in pairs at diagonal corner sections. The mounting hole section 141 has a through-hole 142 that penetrates the flange 111. The flange 111 is fastened to the intake body 22 by inserting a fastening screw (not shown) into the through-hole 142 of the mounting hole section 141 and screwing the fastening screw into the screw hole of the intake body 22.

[0027] As in Fig. As shown in Figure 2(a), the connector 112 provides four external connections 147 and one correction connection 148. The external connections 147 are for outputting physical quantities such as flow rate and temperature, which are measurement results from the airflow meter 20, and are also for supplying direct current to operate the airflow meter 20.

[0028] The correction port 148 is used to measure the produced airflow meter 20 in order to obtain a correction value specific to each airflow meter 20 and to store this correction value in a memory within the airflow meter 20. In the subsequent measurement process of the airflow meter 20, correction data representing the correction value stored in the memory is used, and the correction port 148 is not used.

[0029] Therefore, the correction port 148 has a different shape than the external port 147, so that the correction port 148 does not obstruct the connection between the external port 147 and another external device. In this embodiment, the correction port 148 has a shorter shape than the external port 147 and is configured so that it does not obstruct the connection even when a connecting port of an external device connected to the external port 147 is inserted into the connector 112.

[0030] The following description explains how in Fig. As shown in Figure 3, the longitudinal direction of the measuring unit 113, which is a direction in which the measuring unit 113 extends from the flange 111, can be called the Z-axis; a short direction of the measuring unit 113, which is a direction extending from the lower channel inlet 131 of the measuring unit 113 towards the first outlet 132, can be called the X-axis; and a thickness direction of the measuring unit 113, which is a direction from the front surface 121 of the measuring unit 113 towards the rear surface 122, can be called the Y-axis.

[0031] The housing 100 is provided with a subchannel groove 150 for forming a subchannel 134 and a circuit chamber 135 for receiving a printed circuit board 311. The circuit chamber 135 and the subchannel groove 150 are formed in the front surface of the measuring unit 113. The circuit chamber 135 is located in an area on one side (side of the side surface 123) in the X-axis direction, which is situated on the upstream side in the direction of the intake air flow 2. Then the under-channel groove 150 is provided above an area on the front end side (side of the lower surface 125) of the measuring unit 113 in the Z-axis direction with respect to the circuit chamber 135 and an area on the other side in the X-axis direction (side of the side surface 124), which is a position on the downstream side in the flow direction of the intake air 2 with respect to the circuit chamber 135.

[0032] The sub-channel groove 150 is covered by the cover 200 to form the sub-channel 134. The sub-channel groove 150 comprises a first sub-channel groove 151 and a second sub-channel groove 152, which branches off from the center of the first sub-channel groove 151. The first sub-channel groove 151 is designed to extend along the X-axis direction of the measuring unit 113 between the sub-channel inlet 131, which opens to the side surface 123 on one side of the measuring unit 113, and the first outlet 132, which opens to the side surface 124 on the other side of the measuring unit 113. The first sub-channel groove 151, together with the cover 200, forms a first sub-channel A, which draws in the intake air 2 from the sub-channel inlet 131 and returns the drawn-in intake air 2 from the first outlet 132 to the main channel 22a.The first sub-channel A has a flow path that extends from the sub-channel inlet 131 along the flow direction of the intake air 2 in the main channel 22a and is connected to the first outlet 132.

[0033] The second subchannel groove 152 branches at the intermediate position of the first subchannel groove 151, bends towards the side of the proximal end section (flange side) of the measuring unit 113, and extends in the direction of the Z-axis of the measuring unit 113. Then, at the proximal end section of the measuring unit 113, the second subchannel groove bends towards the other side (side of the side surface 124) of the measuring unit 113 in the X-axis direction, rotates towards the distal end section of the measuring unit 113, and again extends along the Z-axis direction of the measuring unit 113. Then, in front of the first outlet 132, the second subchannel groove bends towards the other side (the side of the side surface 124) of the measuring unit 113 in the X-axis direction and is positioned so that it is continuous with the second outlet 133, which opens towards the side surface 124 of the measuring unit 113.The second outlet 133 is arranged such that it faces the downstream side of the main channel 22a in the direction of the intake air flow 2. The second outlet 133 has an opening area that is essentially equal to or slightly larger than that of the first outlet 132 and is located at a position adjacent to the side of the proximal end section of the measuring unit 113 in the longitudinal direction with respect to the first outlet 132.

[0034] The second sub-channel groove 152, in conjunction with the cover 200, forms a second sub-channel B, which allows the intake air 2 branched off from and flowing in from the first sub-channel A to pass through and returns the intake air 2 from the second outlet 133 to the main channel 22a. The second sub-channel B has a flow path for a back-and-forth movement along the Z-axis direction of the measuring unit 113.That is, the second subchannel B has a forward channel section B1, which branches off in the middle of the first subchannel A and extends towards the side of the proximal end section of the measuring unit 113 (in a direction away from the first subchannel A), and a return channel section B2, which is folded back and inverted on the side of the proximal end section (the end section of a separating channel section) of the measuring unit 113 and extends towards the side of the distal end section (in a direction approaching the first subchannel A) of the measuring unit 113. The return channel section B2 is connected to the second outlet 133, which is open to the downstream side in the direction of flow of the intake air 2 at a position on the downstream side in the direction of flow of the intake air 2 in the main channel 22a with respect to the subchannel inlet 131.

[0035] In the second subchannel B, the chip packaging 300, which will be described later, is arranged in the intermediate position of the forward channel section B1. Since the second subchannel B is designed to extend along the longitudinal direction of the measuring unit 113 and to be able to move back and forth, the channel length can be maintained for a longer period, and the influence on the chip packaging 300 can be reduced in the event of pulsation in the main channel 22a.

[0036] Similar to the housing 100, the cover 200 is formed by an injection-molded part made of a synthetic resin material and is attached to the side surface of the housing 100 to cover the housing 100. The cover 200 can be manufactured, for example, from a metal material such as an aluminum alloy by precision casting, such as lost-wax casting or die casting.

[0037] As in Fig. 4(a), Fig. 4(b) and Fig. As shown in Figure 5, the chip packaging 300 comprises an airflow metering element (hereinafter referred to simply as the element) 301, a conductor frame 302, a sealing resin part 303, a polyimide tape 304, and a die-attach film (hereinafter referred to as the DAF) 305. The chip packaging 300 is manufactured by placing the element 301 and the conductor frame 302, on which the element 301 is mounted, into a mold, pouring a casting resin into the mold, and thermally curing the casting resin.

[0038] The chip packaging 300 comprises the sealing resin part 303 in the form of a flat plate, which is essentially rectangular in plan view. The sealing resin part 303 has a proximal end section on one longitudinal side, which is located in the circuit chamber 135 of the housing 100, and a distal end section on the other longitudinal side, which is located in the second subchannel B of the housing 100. Several terminal sections T are arranged on the proximal end section of the sealing resin part 303 such that they project in widely separated directions along the short direction. A recessed groove is then formed in the distal end section of the sealing resin part 303, extending along the short direction. The recessed groove is provided on the front face of the distal end section of the sealing resin part 303 and forms a channel Kt through which the intake air 2 flows.The distal end section of the sealing resin part 303 is arranged in the forward channel section B1 and the return channel section B2, which form the second subchannel B of the in . Fig. The chip packaging 300 measures the flow rate of the intake air 2 flowing in the second subchannel B and transmits a signal of the measurement result to the control device 4.

[0039] As in Fig. As shown in Figure 5, element 301 comprises an element body 401, which serves as a substrate. The element body 401 is configured as a flat, plate-shaped element and is connected to the conductor frame 302 by the DAF 305, which is provided between the conductor frame and the rear side. The front side of the element body 401 is free of the sealing resin portion 303 and serves as the detection area. An opening Kd is formed in the element body 401, opening towards the rear side, and a thin-film section 402 is configured to close the opening Kd on the front side of the element body 401.The thin-film section 402 contains a first differential temperature sensor 407, a first heater temperature sensor 405, a heater 404, a second heater temperature sensor 406, and a second differential temperature sensor 408, arranged in the main flow direction of a target medium, and is a sensing section for detecting the flow rate of the target medium. Hereinafter, the arrangement direction is expressed as a lateral direction (short direction) and a direction perpendicular to the arrangement direction as a vertical direction (longitudinal direction). The element 301 has, on the front face of the element body 401, the thin-film section 402 as the sensing section and a circumferential section 403 that extends continuously around the thin-film section 402.

[0040] The thin-film section 402, for example, is configured with a thin film with a thickness of less than a few µm and is exposed to the channel Kt of the sealing resin part 303. As in Fig. As shown in Figure 8(c), the first temperature difference sensor 407, the first heater temperature sensor 405, the heater 404, the second heater temperature sensor 406, and the second temperature difference sensor 408 are formed in the thin-film section 402, and a PIQ layer 409 is formed around the top surface of the thin-film section 402. The thin-film section 402 can measure the flow rate of the intake air 2 flowing through the front surface of the thin-film section 402 based on the temperature distribution in one direction along the surface of the thin-film section 402. In the element body 401, the opening Kd with a frustoconical shape, the opening diameter of which increases with increasing distance from the rear of the thin-film section 402, is formed on the rear side of the thin-film section 402.

[0041] In the state of element 301 as a single body, before it is formed by the sealing resin part 303, the front and rear surfaces of element body 401 have a flat surface shape without curvature. When element 301, together with the conductor frame 302, is formed by the sealing resin part 303, a bending stress is generated due to the contraction of the resin between the sealing resin part 303 and the conductor frame 302. At the time of forming, a change in crosslinking density or a volume contraction between molecules of the sealing resin part 303 occurs during the curing process from a viscous liquid, so that a volume decreases after curing.

[0042] Therefore, a mold contraction rate means that the volume contracts after the sealing resin part injected into the mold has cooled, and a contraction rate (hereinafter referred to as the contraction rate) is generally defined by the following expression (2). [Mathematical Formula 1] Mold contraction rate = Volume immediately after molding - Volume after mold cooling / Volume immediately after molding × 100

[0043] The mold contraction rate is also expressed by the following expression (3) according to standard JIS K6911 in conjunction with a mold condition and a test specimen condition of the sealing resin part 303. If the dimensions of the mold at room temperature are D1, D2, D3 and D4, the dimensions of the molded product at room temperature are d1, d2, d3 and d4, and an average is calculated using four test specimens, the contraction rate of the sealing resin part 303 is obtained by the following expression (3). [Mathematical Formula 2] Mold contraction rate(%) =14×[D1−d1D1+D2−d2D2+D3−d3D3+D4−d4D4]

[0044] When the element 301 is formed by the sealing resin part 303, the side of the front face of the element body 401 is deformed such that it protrudes from a flat shape to a convex shape and curvature. In such a case, the radius of curvature ρ of the exposed section of the element 301, which is free of the sealing resin part 303, is 2.13 or less. More precisely, the circumferential region section 403, which is a region that does not include the thin-film section 402, has a radius of curvature ρ (mm) of 0 or more in the front face of the element body 401 and is shaped such that it satisfies a relationship of ρ ≤ 2.13 in the longitudinal direction of the chip packaging 300, as shown in Fig. 5 shown. As in Fig. As shown in Figure 5, the upper surface of element 301 is in particular a boundary section between element 301 and the sealing resin part 303 covering the upper surface of element 301. The radius of curvature ρ is expressed by the following expression (1). [Mathematical Formula 3] 1ρ=h1+h2+h3+h4+h5h13+h23+h33+h43+h53(1−β)

[0045] For expression (1), as in Fig. Figure 5, however, on the surface of the front side of the sealing resin part 303, in which the element 301 is provided with the conductor frame 302 arranged between them, and on the surface of the rear side of the sealing resin part on the side opposite the element 301, h1 (mm) represents the thickness (hereinafter referred to as the thickness of a rear surface resin part S) of the sealing resin part 303 on the surface of the rear side of the conductor frame 302, h2 (mm) represents the thickness (mm) of the conductor frame 302, h3 (mm) represents the thickness (hereinafter referred to as the thickness of a front surface resin part U) of the sealing resin part 303 on the surface of the front side of the conductor frame 302, h4 (mm) represents the thickness of the element body 401, h5 (mm) represents the thickness of the thin-film section 402, and β (%) represents a Curing contraction rate of the sealing resin part 303.

[0046] The radius of curvature ρ of the circumferential section 403 of the front surface of the element body 401 can be measured by the following method. That is, by cutting the chip packaging 300 at the position of the element 301, the radius of curvature ρ of the front surface of the element body 401, which appears on the cut surface, can be measured. Furthermore, the radius of curvature ρ can be measured non-destructively by a non-contact displacement measurement method using light, e.g., a laser beam. Additionally, the radius of curvature ρ can also be measured non-destructively by scanning the circumferential section 403 of the front surface of the element body 401 with a three-dimensional measuring machine (also known as a 3D scanner).

[0047] The radius of curvature ρ is calculated using a general formula for the bending stress of the sealing resin part 303. Fig. Figure 6(c) shows the elements of the calculation formula and the symbols for the elements. If, for a general beam, the modulus of elasticity is defined as E, a secondary cross-sectional moment as I, and a bending moment as M, and ρ is the radius of curvature of the beam, the following expression (a) results. [Mathematical Formula 4] 1ρ=MEI

[0048] As in Fig. 6(a) is shown in a case where the thin-film section 402 is convexly deformed, [Mathematical Formula 5] 1ρ=MEI<0 fulfilled.

[0049] As in Fig. 6(b) is shown in a case where the thin-film section 402 is deformed concavely, [Mathematical Formula 6] 1ρ=MEI>0 fulfilled. In a laminate, which is to be the sealing resin part 303 of the embodiment, the amount of deformation of the thin-film section 402 is determined by a composite equilibrium of h1, h2 and h3, which is in Fig. Figure 6(c) illustrates this. In this context, the apparent deformation from h1 to h5 is obtained.

[0050] In a case where the curing contraction rate of the resin is β, β has a relationship with the following expression (d). [Mathematical Formula 7] 1ρ∝(1−β)

[0051] From expression (d), into expression (a), is [Mathematical Formula 8] 1ρ=MEI(1−β) fulfilled. The bending moment M is expressed by: [Mathematical Formula 9] M=∑(hi×αi×ΔT) =(h1+h3)α1×ΔT+h2×α2×ΔT+(h4+h5)α3×ΔT =(h1×α1+h2×α2+h3×α1+h4×α3+h5×α3) =ΔT{α1(h1+h3)+α2(h2)+(h4+h5)}

[0052] If E, α and ΔT applied to M are dimensionless, the following expression (g) is obtained. [Mathematical Formula 10] EI∝∑(hi) = h1+h2+h3+h4+h5

[0053] The following expressions (h) and (i) are obtained. [Mathematical Formula 11] M∝∑(112hi3) EI∝∑(hi3)=h13+h23+h33+h43+h53

[0054] If (h) (i) → (f) here, the following expression (j) results. [Mathematical Formula 12] 1ρ=MEI(1−β)=h1+h2+h3+h4+h5h13+h23+h33+h43+h53(1−β)

[0055] Therefore, from expression (a) of the curvature (1 / ρ) of the carrier by a subsequent composite thickness γ of the chip packaging 300 according to the present embodiment, it follows that the deformation of the thin film section 402 is 0 or that the deformation ≤ 3 µm is satisfied in the case of the structure of the present embodiment. [Mathematical Formula 13] γ=h1+h2+h3+h4+h5h13+h23+h33+h43+h53

[0056] If γ is substituted into expression (j) here, then [Mathematical Formula 14] 1ρ=γ(1−β) This condition is met, and a general formula for curvature is obtained. The specific verification of this general formula will be described later.

[0057] The conductor frame 302 consists of a thin plate of metallic material, such as copper (Cu) with high conductivity, and includes a pattern section (not shown) and a terminal section T, as shown in Fig. 4(a) shows the connection section T is connected to a connection surface of the printed circuit board 311. The conductor frame 302 supports and fixes the element 301 via the DAF 305. That is, the element 301 is mounted on the conductor frame 302. In the conductor frame 302, as shown in Fig. Figure 5 shows a through-hole Kh formed to communicate with the opening Kd of the thin-film section 402, and a through-hole Ku formed to communicate with an opening K3 of the front surface resin part U, which will be described later. The through-hole Kh and the through-hole Ku are connected by a connecting path R (see Figure 5). Fig. 4(b)). The through-hole Kh, the through-hole Ku and the connecting path R function such that the pressure in the opening Kd of the thin-film section 402 is essentially equal to atmospheric pressure.

[0058] As in Fig. 4(b) and Fig. As shown in Figure 5, the sealing resin part 303 has a rear surface resin part S with thickness h1 and a front surface resin part U with thickness h3, both made of a synthetic resin material, a so-called molding resin. The thickness h3 of the front surface resin part U is twice or greater than the thickness h1 of the rear surface resin part S. The sealing resin part 303 covers the element 301 and the conductor frame 302 with the rear surface resin part S and the front surface resin part U to integrate the components. A material with a curing contraction rate β of 0.18% or more is selected as the molding resin. The material of the molding resin is not particularly limited as long as the molding resin is a synthetic resin with a curing contraction rate β of 0.18% or more.

[0059] As in Fig. 4 and Fig. As shown in Figure 5, the perimeter of the thin-film section 402 and the thin-film section 402 itself are exposed in the sealing resin part 303 to form the channel Kt for the passage of an airflow. Furthermore, an opening (opening section) K1 in the shape of a truncated cone is formed in the rear surface resin part S of the sealing resin part 303, the opening diameter of which increases with increasing distance from the conductor frame 302. The opening K1 is provided at a position opposite the element 301, with the conductor frame 302 positioned between them. Additionally, an opening K2 is formed in the front surface resin part U of the sealing resin part 303 at the end section opposite the channel Kt in the longitudinal (vertical) direction of the sealing resin part 303.Then, in the rear surface resin part S of the sealing resin part 303, the opening K3 is formed at the end section that is opposite the opening K1 in the longitudinal direction of the sealing resin part 303.

[0060] As in Fig. 4(b) and Fig. As shown in Figure 5, the sealing resin part 303 has the recessed, groove-shaped channel Kt on its front surface. The channel Kt of the sealing resin part 303 has a pair of channel walls Th and a bottom wall at which the front surface of the element body 401 is exposed. The pair of channel walls Th has a throttled shape in which the opening area (cross-sectional area) of the channel Kt gradually narrows towards the thin-film section 402, which serves as the detection section. In the sealing resin part 303, the pair of channel walls Th forming the channel Kt covers both lateral edges of the element 301 in a direction orthogonal to the airflow passing through the channel Kt, and the front surface resin part U is designed such that the thin-film section 402 is exposed to the channel Kt.Therefore, when the sealing resin part 303 is deformed by thermal contraction, the element 301 is also deformed together with the sealing resin part 303 by receiving a stress from the front surface resin part U.

[0061] The polyimide tape 304 consists of a polymer compound containing an imide bond and exhibits high heat resistance, excellent mechanical properties, and chemical resistance. The polyimide tape 304 is applied to the surface of the conductor frame 302 opposite the surface on which the element 301 is mounted, and it blocks the through-hole Kh, the through-hole Ku, and the connecting path R of the conductor frame 302.

[0062] The DAF 305 consists of a high-adhesion adhesive film material and is inserted between the element 301 and the conductor frame 302 to bond the element 301 and the conductor frame 302. The DAF 305 is provided with an opening that establishes a connection between the opening Kd of the thin-film section 402 and the through-hole Kh of the conductor frame 302.

[0063] In the chip packaging 300 according to the present embodiment, the sealing resin part 303 contracts thermally during curing at the time of its formation, and deformation occurs in the thin-film section 402. However, the occurrence of this deformation has been specifically investigated. As the magnitude (mm) of the deformation of the thin-film section 402 increases, the measurement accuracy of the intake air flow rate 2 decreases; therefore, the magnitude of the deformation of the thin-film section 402 is preferably kept small. Various factors, such as the magnitude of the deformation of the thin-film section 402, a relationship between the thin-film section 402 and the curing contraction rate β, and the radius of curvature ρ, are described in more detail below with reference to the drawings. <Wirkung der thermischen Kontraktion des Versiegelungsharzteils 303 und Betrag der Verformung des Dünnfilmabschnitts 402>

[0064] First, the effect of the thermal contraction of the sealing resin part 303 and the amount of deformation of the thin-film section 402 were specifically verified in Examples 1 and 2 and Comparative Examples 1 and 2 of the chip packaging 300 according to the present embodiment. It should be noted that when using the flat front surface of the thin-film section 402 before the deformation occurs as a reference, the amount (mm) of deformation of the thin-film section 402 refers to a height (mm) from the reference of the thin-film section 402, which assumes a convex shape due to the deformation, to the top of the convex shape.

[0065] In the chip packaging according to comparative example 1, as in Fig. Figure 7 shows that the linear coefficient of thermal expansion α (ppm / °C) of the conductor frame 302 is 17.7, and an intermediate element 306 is inserted between the element 301 and the conductor frame 302. The linear coefficient of thermal expansion α of the element 301 is 3, the linear coefficient of thermal expansion α of the packaging is 7, and the curing contraction rate β (%) of the molding resin is 0.11 or 0.3.

[0066] In the chip packaging according to comparative example 2, the linear expansion coefficient α of the conductor frame 302 is 17.7, there is no intermediate element between the element 301 and the conductor frame 302, the linear expansion coefficient α of the element 301 is 3, the linear expansion coefficient α of the molding resin of the sealing resin part 303 is 7, and the curing contraction rate β of the molding resin of the packaging is 0.11.

[0067] In the chip packaging 300 according to example 1, as in Fig. As shown in Figure 7, the linear expansion coefficient α of the conductor frame 302 is 17.7, there is no intermediate element between the element 301 and the conductor frame 302, the linear expansion coefficient α of the element 301 is 3, the linear expansion coefficient α of the molding resin of the sealing resin part 303 is 7, and the curing contraction rate β of the molding resin of the sealing resin part 303 is 0.3.

[0068] In the chip packaging 300 according to Example 2, the linear expansion coefficient α of the conductor frame 302 is similar to that of the airflow meter 20 according to Example 1, 17.7; there is no intermediate element between the element 301 and the conductor frame 302; the linear expansion coefficient α of the element 301 is 3; the linear expansion coefficient α of the molding resin of the sealing resin part 303 is 7; and the curing contraction rate β of the molding resin of the sealing resin part 303 is 0.3.

[0069] As in Fig. As shown in Figure 7, in the chip packaging 300 according to Example 2, the inner diameter of the through hole Kh of the conductor frame 302 is larger than in the chip packaging 300 according to Example 1.

[0070] In the chip packaging according to Comparative Example 1, when the molding resin contracts thermally during curing, a compressive force (N), expressed by (-), acts towards the central section of element 301, and a tensile force (N), expressed by (+), acts away from the central section of element 301 on the molding resin. A compressive force towards the central section of element 301 acts on element 301, the intermediate element 306, and the conductor frame 302. In the chip packaging according to Comparative Example 1, the intermediate element 306 can absorb the compressive force generated by the contraction of the conductor frame 302, and the accumulation of the compressive force from the conductor frame 302 in element 301 can be prevented.

[0071] In the chip packaging according to Comparative Example 1, the compressive force acting on element 301 and the intermediate element 306 and the tensile force acting on the sealing resin part 303 are balanced, the force acting on the thin-film section 402 disappears, and the deformation of the thin-film section 402 is eliminated. In Comparative Example 1, the occurrence of a deformation of the thin-film section 402 is suppressed by the presence of the intermediate element 306 regardless of the magnitude of the curing contraction rate, even if the curing contraction rate β of the molding resin is 0.11 or 0.3.

[0072] In the chip packaging according to Comparative Example 2, similar to Comparative Example 1, when the molding resin of the sealing resin part 303 contracts thermally during curing, a compressive force acts on the sealing resin part 303 in the direction of the central section of element 301 and a tensile force acts on it in a direction away from the central section of element 301. A compressive force acts on element 301 and the conductor frame 302 in the direction of the central section of element 301. Since the intermediate element is not provided in Comparative Example 2, the compressive force generated by the contraction of the conductor frame 302 acts directly on element 301 and accumulates. Therefore, a compressive force acts on the thin-film section 402, and the amount of deformation of the thin-film section 402 is increased.

[0073] In the chip packaging 300 according to example 1, as in Fig. As shown in Figure 7, when the molding resin of the sealing resin part 303 contracts thermally at the time of curing, a relatively large compressive force acts in the direction of the central section of the element 301 and a relatively large tensile force acts in a direction away from the central section of the element 301 on the sealing resin part 303, and a compressive force in the direction of the central section of the element 301 acts on the element 301 and the ladder frame 302.

[0074] As a result, the tensile force acting on the sealing resin part 303 increases relative to the compressive force acting on element 301 and the ladder frame 302, and the deformation of the sealing resin part 303 increases. As the deformation of the sealing resin part 303 increases, a relatively small compressive force acts on the thin-film section 402, and the amount of deformation of the thin-film section 402 is reduced compared to Comparative Example 2. It can therefore be seen that the deformation of the thin-film section 402 is reduced by actively deforming element 301 in a tensile direction.

[0075] In the chip packaging 300 according to Example 2, similar to Example 1, when the molding resin of the sealing resin part 303 contracts thermally at the time of curing, a relatively large compressive force acts in the direction of the central section of the element 301 and a relatively large tensile force acts in a direction away from the central section of the element 301 on the sealing resin part 303 and a compressive force acts in the direction of the central section of the element 301 on the element 301 and the conductor frame 302.

[0076] In Example 2, however, unlike Example 1, the through-hole Kh of the ladder frame 302 is larger than the through-hole Kh of Example 1, so that the compressive force acting on the ladder frame 302 is halved and relatively small. As a result, the tensile force acting on the sealing resin part 303 increases relative to the compressive force acting on the element 301 and the ladder frame 302, and the deformation of the sealing resin part 303 increases. When the deformation of the sealing resin part 303 increases, a relatively small compressive force acts on the thin-film section 402, and the amount of deformation of the thin-film section 402 is greatly reduced compared to Example 1. Therefore, it can be seen that the deformation of the thin-film section 402 is largely offset by the deformation of the element 301 in the tensile direction.

[0077] As can be seen from the results of Comparative Example 1, Comparative Example 2, Example 1, and Example 2, the contraction of the conductor frame 302, i.e., a so-called return amount, is greater than that of element 301 due to the difference in the linear expansion coefficient α of each component when the sealing resin part 303 is cooled from the mold temperature to a normal temperature, causing the thin-film section 402 to compress and deform. If, at this time, the curing contraction rate β of the mold resin of the sealing resin part 303 is large, the compressive stress of the thin-film section 402, generated by the contraction of the conductor frame 302, can be mitigated by the tensile force acting on the sealing resin part 303.

[0078] Therefore, the stress is hardly concentrated on the thin-film section 402, and the occurrence of a deformation of the thin-film section 402 is suppressed. In comparison to Example 2, the chip packaging 300 of Example 1 and Example 2 exerts the tensile force on the element 301, so that the deformation of the thin-film section 402 due to the compressive stress acting on the element 301, i.e., the compressive force acting on the element 301, is reduced. <Betrag der Verformung des Dünnfilmabschnitts 402 in seitlicher Richtung und in vertikaler Richtung>

[0079] Next, a relationship between the amount (mm) of deformation of the thin-film section 402 in the lateral direction and the amount of deformation (mm) in the vertical direction was specifically verified for the same configuration with the intermediate element as in the above-described comparative example 1 and the same configuration as in the above-described example 1 in the chip packaging 300 according to the present embodiment. In this verification, for the in Fig. 8(a) The chip packaging 300 shown requires the criterion of the amount (mm) of deformation of the thin-film section 402, i.e., the criterion for determining an allowable amount of deformation. Note that in the curve of Fig. 9. A black circle indicates the chip packaging 300 with a configuration without the intermediate element, and a black square indicates the chip packaging with a configuration including the intermediate element. Furthermore, the two columns of the curve on the right-hand side show... Fig. 9 The left curves show the amount of deformation of the membrane in the lateral direction and the right curves show the amount of deformation of the membrane in the vertical direction.

[0080] Regarding the lateral and vertical directions of the thin-film section 402, as described in Fig. 8(b) and Fig. Figure 8(d) shows a direction that is the longitudinal direction (X-axis direction) of the chip packaging 300 and orthogonal to a flow direction of the intake air 2, defined as the vertical direction, and a direction that is the short direction (Z-axis direction) of the chip packaging 300 and a flow direction of the intake air 2, defined as the lateral direction. If, as in Fig. As shown in Figure 9, the lateral deformation of thin-film section 402 is 10 µm to 11 µm, and the vertical deformation is also 12 µm to 14 µm, both of which are significant deformation values. When the vertical deformation of thin-film section 402 is 12 µm to 14 µm, the shape of the deformation in the vertical direction becomes two peaks in the curve of the relationship between the deformation value and the distance. Therefore, thin-film section 402 protrudes, the temperature distribution becomes NG, and the measurement accuracy of thin-film section 402 cannot be achieved.

[0081] If the lateral deformation of thin-film section 402 is 7 µm to 9 µm, the vertical deformation will also be 8 µm to 12 µm, both of which are significant deformation values. If the vertical deformation is 8 µm to 12 µm, the shape of the vertical deformation will exhibit two peaks in the curve representing the relationship between the deformation value and the distance. Therefore, in this case as well, thin-film section 402 will protrude, the temperature distribution will become undefined, and the measurement accuracy of thin-film section 402 cannot be achieved.

[0082] If the lateral deformation of thin-film section 402 is 4 µm to 6 µm, the vertical deformation will also be 6 µm to 8 µm, both of which are relatively large deformation values. If the lateral deformation of thin-film section 402 is 6 µm to 8 µm, the shape of the deformation will follow the curve of the relationship between the deformation value and the distance to two peaks, and in this case, too, the required measurement accuracy of thin-film section 402 cannot be achieved.

[0083] However, if the lateral deformation of the thin-film section 402 is 0.5 µm to 1 µm, and the vertical deformation is 3 µm to 4 µm, both of which are relatively small. In this case, as with the lateral and vertical deformations, the deformation of the thin-film section 402 is reduced along the curve of the relationship between the deformation magnitude and the distance, and the curve has a flat shape without peaks. Therefore, the shapes of the thin-film section 402 in both the lateral and vertical directions are flat surfaces, and both exhibit a favorable temperature distribution, allowing for measurement accuracy.

[0084] If, in the configuration with the intermediate element as in Comparative Example 1, the lateral deformation of the thin-film section 402 is 1.5 µm, and the vertical deformation is 2 µm, both of which are relatively small. In this case, as with the lateral and vertical deformations, the deformation of the thin-film section 402 is reduced along the curve of the relationship between the deformation magnitude and the distance, and the curve is a flat curve without peaks. Therefore, the shapes of the thin-film section 402 are flat surfaces in both the lateral and vertical directions, and both exhibit a favorable temperature distribution, allowing for the achievement of measurement accuracy.

[0085] To ensure measurement accuracy, the amount of deformation of the thin-film section 402 is small, and in the curve of the relationship between the amount of deformation and the distance in both the lateral and vertical directions, it is assumed that the shape of the deformation has no two peaks and is flat. As in Fig. However, as shown in Figure 9, it was found that if the deformation of the thin film section 402 is 3 µm or less, an accuracy at the same level as that of the chip packaging with the configuration containing the intermediate element can be achieved. <Aushärtungskontraktionsrate des Formharzes und Betrag der Verformung des Dünnfilmabschnitts 402>

[0086] Next, the relationship between the curing contraction rate of the molding resin of the sealing resin part 303 and the amount of deformation of the thin-film section 402 in the chip packaging 300 according to the present embodiment was specifically verified. In this verification, the optimal value of the curing contraction rate β of the molding resin for the [missing information] was determined. Fig. 10(a) chip packaging 300 determined.

[0087] As in Fig. As shown in Figure 10(a), if the curing contraction rate of the resin is 0.3%, the amount of deformation of the thin-film section 402 is 1.5 µm; if the curing contraction rate of the resin is 0.14%, the amount of deformation of the thin-film section 402 is approximately 3.2 µm; if the curing contraction rate of the resin is approximately 0.12%, the amount of deformation of the thin-film section 402 is approximately 3.5 µm; if the curing contraction rate of the resin is approximately 0.11%, the amount of deformation of the thin-film section 402 is approximately 3.9 µm; and if the curing contraction rate of the resin is approximately 0.09%, the amount of deformation of the thin-film section 402 is approximately 4.2 µm. µm.

[0088] As described above, if the deformation of the thin-film section 402 is 3 µm or less, accuracy at the same level as that of the chip packaging with the configuration including the intermediate element can be achieved, but four points marked with black circles, where the curing contraction rate of the resin is approximately 0.14% or less, exceed 3 µm. If the points marked with black circles are connected by a straight dashed line, as in Fig. As shown in Figure 10(a), it can also be seen that the curing contraction rate of the resin is 0.18% and the amount of deformation of the thin-film section is 402.3 µm. Therefore, it follows that the optimal value of the curing contraction rate of the resin is 0.18% or more. <Beziehung zwischen der Verformung des Versiegelungsharzteils 303 und der Verformung des Dünnfilmabschnitts 402>

[0089] Next, the relationship between the deformation of the sealing resin part 303 and the deformation of the thin-film section 402 in the chip packaging 300 according to the present embodiment was specifically verified. The deformation of the sealing resin part 303 represents the deformation at the lower surface of the rear surface resin part S of the sealing resin part 303, as shown in Fig. 10(b) is shown. In the Fig. In the diagram shown in Figure 10(b), sample 1 is configured similarly to Example 1 described above, and sample 2 is configured similarly to Example 2 described above. Note that the amount of deformation of the sealing resin part 303 is represented by a bar chart, and the amount of deformation of the thin-film section 402 is represented by a polygonal line.

[0090] If the curing contraction rate of the resin is 0.09%, the amount of deformation of the sealing resin part 303 of sample 1 is approximately 5.2 µm, the amount of deformation of the thin film section 402 is approximately 5.2 µm, the amount of deformation of the sealing resin part 303 of sample 2 is approximately 5.8 µm, and the amount of deformation of the thin film section 402 is approximately 4.2 µm. If the resin curing contraction rate is 0.11%, the amount of deformation of the sealing resin part 303 of sample 1 is approximately 5.5 µm, the amount of deformation of the thin-film section 402 is approximately 4.8 µm, the amount of deformation of the sealing resin part 303 of sample 2 is approximately 5.5 µm, and the amount of deformation of the thin-film section 402 is approximately 4.8 µm. If the resin curing contraction rate is 0.12%, the amount of deformation of the sealing resin part 303 of sample 2 is approximately 6.5 µm, and the amount of deformation of the thin-film section 402 is approximately 3.5 µm.If the resin curing contraction rate is 0.14%, the amount of deformation of the sealing resin part 303 of sample 2 is approximately 6.6 µm and the amount of deformation of the thin-film section 402 is approximately 3.2 µm. If the resin curing contraction rate is 0.3%, the amount of deformation of the sealing resin part 303 of sample 1 is approximately 7.5 µm, the amount of deformation of the thin-film section 402 is approximately 2.2 µm, the amount of deformation of the sealing resin part 303 of sample 2 is approximately 7.8 µm, and the amount of deformation of the thin-film section 402 is approximately 1.5 µm.

[0091] As in Fig. As shown in Figure 10(b), it can be seen that if the curing contraction rate of the resin in sample 1 and sample 2 is 0.18% or more, the application of a configuration without intermediate elements is possible. Furthermore, as the curing contraction rate of the resin increases, the deformation of the sealing resin part 303 also increases, and it can be seen that the curing contraction rate of the resin and the deformation of the sealing resin part 303 are in a proportional relationship. Conversely, as the deformation of the sealing resin part 303 increases, the deformation of the thin-film section decreases, and it can be seen that the deformation of the sealing resin part 303 and the deformation of the thin-film section 402 are inversely proportional.Furthermore, it can also be seen that a tensile force acts on element 301 due to an increase in the curing contraction rate of the resin and the deformation of the sealing resin part 303, and the deformation of the thin film section 402 is reduced. <Verhältnis der Verformung in jeder Konfiguration>

[0092] Next, the ratio of deformation in each configuration in the chip packaging 300 according to the present embodiment was re-verified. As in Fig. As shown in Figure 11(a), in a case where the curing contraction rate of the resin is 0.09%, the amount of deformation of the thin-film section 402 is 4.4 µm. When the deformation of the sealing resin part 303 is small, the deformation of the thin-film section 402 increases, and it can be seen that there is an inverse relationship between the two. As shown in Fig. As shown in Figure 11(b), in a case where the curing contraction rate of the resin is 0.3%, the amount of deformation of the thin-film section 402 is 1.5 µm. If the deformation of the sealing resin part 303 is large, the deformation of the thin-film section 402 decreases, and it can be seen that there is an inverse relationship between the two. <Berechnung spezifischer numerischer Werte unter Verwendung der allgemeinen Formel>

[0093] Next, regarding the specific numerical values ​​of the deformation in each configuration in the chip packaging 300 according to the present embodiment, a verification was carried out using the thickness h5 of the thin-film section 402, which was inserted as a parameter in expression (1) of the radius of curvature ρ. The amount of deformation of the thin-film section 402 was obtained here by a thermal stress analysis (from before cooling to after cooling). The specific numerical values ​​and parameters were those in Fig. The 12 described numerical values ​​are used. It should be noted that values ​​other than parameter h5 are fixed values. Regarding the calculated curvature 1 / p and the radius of curvature ρ, in a case where h5 is 0.0005, 1 / p is 0.461 and ρ is 2.168; in a case where h5 is 0.001, 1 / p is 0.477 and ρ is 2.095; in a case where h5 is equal to 0.002, 1 / p is equal to 0.491 and ρ is equal to 2.037; in a case where h5 is equal to 0.0047, 1 / p is equal to 0.505 and ρ is equal to 1.980; and in a case where h5 is equal to 0.008, 1 / p is equal to 0.509 and ρ is equal to 1.983.

[0094] From the relationship between the curing contraction rate β and the deformation of the thin-film section 402 in Fig. 13 shows that the optimal value is that the amount of deformation of the thin film section 402 is 3 µm or less and the curing contraction rate β is 0.18 % or more.

[0095] When the calculation result is checked in light of these optimal values, it can be determined that the curvature 1 / p is 0.47 or greater. Converting the curvature 1 / ρ to the radius of curvature ρ, it can be determined that the radius of curvature ρ is 2.13 or less. Furthermore, it can be seen that the optimal value of the ratio h3 / h1 between the thickness of the front surface resin part U and the thickness of the rear surface resin part S is twice or more. It should be noted that the optimal value of the curing contraction rate β has been found to be 0.18%. < actual measurement of the radius of curvature p>

[0096] Next, the radius of curvature ρ of the upper surface of element 301 in the chip packaging 300 according to the present embodiment was actually measured, and it was checked whether the result agreed with the calculation result of the general formula or not. As in Fig. As shown in Figure 14, the VR-3000 of a 3D scanner was used as a measuring instrument. The measuring position was set on the oxide film area of ​​element 301, and the radius of curvature ρ was derived using the measuring method, which is based on the exposed dimension (the width of the intake air channel 2) of element 301.

[0097] In the measurement result, as in the curve of Fig. As shown in Figure 14, ρ is 2.76 mm in a case where the resin's curing contraction rate β is 0.11%, and the amount of deformation of the thin-film section 402 was approximately 4.8 mm. When the resin's curing contraction rate β is 0.3%, ρ is 2.05 mm, while the amount of deformation of the thin-film section 402 is approximately 1.5 mm. Thus, it was found that the measured value of the radius of curvature ρ agrees with the calculation result of the general formula.

[0098] The following describes the effects of the chip packaging 300 according to the present embodiment. (1) The chip packaging 300 according to the present embodiment comprises the conductor frame 302, the element 301 mounted on the conductor frame 302 and comprising the thin-film section 402, and the sealing resin part 303, which seals the conductor frame 302 and the element 301 such that at least the thin-film section 402 is exposed. The radius of curvature ρ of the exposed section of the element 301, which is exposed by the sealing resin part 303, is then 2.13 or less.

[0099] In the chip packaging 300 according to the present embodiment, the element 301 is shaped such that a condition is met that the radius of curvature ρ (mm) of the exposed section of the element 301, which is exposed by the sealing resin part 303, is 2.13 or less, and thus it is possible to achieve an effect of suppressing the occurrence of deformation in the thin-film section 402 when the sealing resin part 303 is formed to seal the element 301 and the conductor frame 302.This means that the condition that the radius of curvature ρ (mm) of the circumferential section in the surface of element 301 after curing of the molding resin forming the sealing resin part 303 is 2.13 or less (p ≤ 2.13) is met, and thus there is an effect that the amount of deformation of the thin-film section 402 is within 3 µm of the optimal value, the flatness of the front surface of the thin-film section 402 is ensured, and the chip packaging 300, which is able to accurately measure the flow rate of the intake air 2, can be obtained.

[0100] In the chip packaging 300 according to the present embodiment, ρ satisfies the relationship of the following expression (1), and thus it is possible to achieve an effect that ρ ≤ 2.13 can be reliably calculated by appropriately selecting h1 to h5 and the curing contraction rate β of the chip packaging 300. [Mathematical Formula 15] 1ρ=h1+h2+h3+h4+h5h13+h23+h33+h43+h53(1−β) (2) In the chip packaging 300 according to the present embodiment, the curing contraction rate β of the mold resin forming the sealing resin part 303 is 0.18% or more, such that when the sealing resin part 303 cools from the mold temperature to normal temperature, it can be deformed in a direction of active deformation, causing the front surface of the sealing resin part to become convex. Therefore, it is possible to achieve the effect of mitigating the compressive stress on the thin-film section 402, which is generated by the contraction of the conductor frame 302, by the tensile force acting on the mold resin, and it is possible to prevent the concentration of stress on the thin-film section 402 and suppress its deformation.

[0101] This makes it possible to achieve an effect that ensures the measurement accuracy corresponds to that of a conventional chip packaging where the intermediate element is provided to adjust the linear expansion coefficient α and reduce the deformation of the thin-film section 402. The chip packaging 300 according to the present embodiment is not provided with the intermediate element, and thus it is possible to achieve a reduction in production costs compared to the conventional chip packaging with the intermediate element. (3) In the chip packaging 300 according to the present embodiment, the sealing resin part 303 has the recessed, groove-shaped channel Kt with the pair of channel walls Th and the bottom wall, from which the front surface of the element body 401 is exposed, wherein the pair of channel walls Th, forming the channel Kt of the sealing resin part 303, covers both side edges of the element 301 in the direction perpendicular to the airflow, and the thin-film section 402 is exposed to the channel Kt. In this configuration, when the sealing resin part 303 is cooled from the mold temperature to normal temperature and the front surface resin part U of the sealing resin part 303 contracts and deforms, the element 301 also deforms together with the front surface resin part U, and a tensile force acts on the thin-film section 402, thus reducing the amount of deformation of the thin-film section. (4) In the chip packaging 300 according to the present embodiment, the maximum thickness (mm) h3 of the front surface resin part U, which is the thickness of the sealing resin part 303 on the side of the front surface (element 301 side) of the conductor frame 302, is configured to be twice or more than the maximum thickness (mm) h1 of the rear surface resin part S, which is the thickness of the sealing resin part 303 on the side of the rear surface of the conductor frame 302. In this configuration, when the sealing resin part 303 is cooled from the mold temperature to normal temperature, the front surface resin part U of the sealing resin part 303 is effectively contracted and deformed, exerting a tensile force on the thin-film section 402, thus reducing the amount of deformation of the thin-film section. (5) In the chip packaging 300 according to the present embodiment, the through-hole Kh is formed in a part of the conductor frame 302 in an area obtained by the thin-film section 402 projecting onto the conductor frame 302 in a direction perpendicular to the front face of the element 301, and the polyimide tape 304 is attached to the side of the rear face of the conductor frame 302 to cover the through-hole Kh. With this configuration, the connection path R, which communicates with the outside of the sealing resin part 303, can be formed, and the pressure acting on the thin-film section 402 can be equalized to atmospheric pressure. (6) In the chip packaging 300 according to the present embodiment, the sealing resin part 303 has the opening section K1, so that part of the strip 304 is exposed. (7) The opening section K1 has the shape of a truncated cone, the diameter of which increases with increasing distance from the conductor frame 302. (8) The channel wall Th has a throttling shape in which the opening area of ​​the channel Kt gradually narrows towards the thin-film section 402 (capture section). (9) The resin-sealed packaging is produced by carrying out a resin sealing such that the curing contraction rate β of the sealing resin part 303 is 0.18% or more. (10) The resin-sealed packaging is produced by carrying out a resin sealing such that the radius of curvature ρ of the exposed section of element 301, which is exposed by the sealing resin part 303, is 2.13 or less.

[0102] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the embodiment described above, and various design changes can be made without departing from the spirit of the present invention as described in the claims. For example, the embodiment described above has been described in detail for ease of understanding of the invention and is not necessarily limited to those with all the configurations described. Furthermore, a part of the configuration of a particular embodiment can be replaced by the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a particular embodiment. It is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. Reference symbol list 100 cases 113 Unit of measurement 131 Lower channel inlet 134 Subchannel 135 Circuit chamber 150 lower channel groove 151 First lower channel groove 152 second lower channel groove 300 chip pack (resin-sealed pack) 301 Element (Airflow Metering Element) 302 ladder frames 303 Sealing resin part 304 Polyimide tape 305 DAF 401 Element bodies 402 Thin film section (capture section) Kt Canal The canal wall ρ radius of curvature β Curing contraction rate QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2013120103 A

[0003]

Claims

[1] Airflow meter comprising a resin-sealed package with a ladder frame an airflow measuring element mounted on the ladder frame and having a sensing section, and a sealing resin part that seals the conductor frame and the airflow measuring element in such a way that at least the sensing section is exposed, wherein a radius of curvature ρ of an exposed section of the airflow metering element, which is free from the sealing resin part, is 2.13 or less. [2] Airflow meter according to claim 1, wherein the curing contraction rate β of the sealing resin part is 0.18% or more. [3] Airflow meter according to claim 1 or 2, wherein the sealing resin part has a recessed, groove-shaped channel with a pair of channel walls and a bottom wall from which the capture section is exposed, and the pair of channel walls that form the channel of the resin-sealed packing, covering both side edges of the airflow metering element. [4] Airflow meter according to claim 3, wherein the maximum thickness h3 of the sealing resin part on a sensor element side with respect to the conductor frame is twice as large or greater than the maximum thickness h1 of the sealing resin part on the side of a rear surface with respect to the conductor frame. [5] Airflow meter according to claim 4, wherein in the ladder frame a hole is formed in an area obtained by projecting the detection section onto the ladder frame in a direction perpendicular to a front surface of the airflow measuring element, and A band is attached to the side of the rear surface of the ladder frame to cover the hole. [6] Airflow meter according to claim 5, wherein the sealing resin element has an opening section so that part of the band is exposed. [7] Airflow meter according to claim 6, wherein the opening section has a frustoconical shape, the opening diameter of which increases with increasing distance from the conductor frame. [8] Airflow meter according to one of claims 3 to 7, wherein the duct wall has a throttle shape in which an opening area of ​​the duct gradually narrows towards the detection section. [9] Method for producing a resin-sealed packaging by inserting an airflow meter and a ladder frame on which the airflow meter is mounted into a mold, infusing a mold resin of a sealing resin part into the mold and thermally curing the mold resin, wherein the resin sealing is carried out such that the curing contraction rate β of the sealing resin part is 0.18% or more. [10] Method for producing the resin-sealed packaging according to claim 9, wherein the resin sealing is carried out such that a radius of curvature ρ of an exposed section of the airflow metering element, which is exposed by the sealing resin part, is 2.13 or less.