Air flow measuring device

Abstract

The present application obtains the following air flow measuring device: when the air flow measuring element is attached to the lead frame and the resin sealing package that seals the air flow measuring element and the lead frame is formed, the thin film part will not be warped, and the flow of air can be accurately measured. The chip package (300) has: a lead frame (302); an element (301) attached to the lead frame (302), having a detection part; and a structure that seals the lead frame and the element (301) in a way that at least the detection part is exposed. Moreover, the air flow measuring device is characterized in that the radius of curvature (p) of the exposed part of the element (301) exposed from the sealing resin member (303) is 2.13 or less.

Description

Technical Field

[0001] The present invention relates, for example, to an air flow measuring device for measuring the flow rate of air drawn into an internal combustion engine of a vehicle. Background Technology

[0002] As such an airflow measuring device, there is, for example, the technology described in Patent Document 1.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-120103 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the air flow measuring device described in Patent Document 1, the coefficients of linear expansion of the air flow measuring element and the lead frame on which the air flow measuring element is mounted are different. Therefore, when a resin-sealed package is formed by sealing the air flow measuring element and the lead frame with synthetic resin, the stress caused by the thermal shrinkage of the synthetic resin acts on the thin film portion, which may warp in the direction of protruding from the cavity portion. If the thin film portion warps, it becomes difficult to measure the air flow with high accuracy.

[0008] On the other hand, when intermediate components such as glass plates or silicon plates with a coefficient of linear expansion similar to that of the air flow measuring element are placed between the air flow measuring element and the lead frame in order to mitigate the warping of the thin film, there are problems such as an increase in the number of parts and assembly time, which leads to an increase in the cost of the air flow measuring device and an increase in the thickness of the intermediate components.

[0009] The present invention was made to solve such a problem, and its object is to provide an air flow measuring device that can suppress warping of the thin film portion and accurately measure the air flow when the air flow measuring element is mounted to the lead frame and a resin sealing package is formed to seal the air flow measuring element and the lead frame.

[0010] Technical means to solve the problem

[0011] The air flow measuring device of the present invention includes a resin sealing package having: a lead frame; an air flow measuring element attached to the lead frame and having a detection portion; and a sealing resin member that seals the lead frame and the air flow measuring element with at least the detection portion exposed. The air flow measuring device is characterized in that the radius of curvature ρ of the exposed portion of the air flow measuring element exposed from the sealing resin member is 2.13 or less.

[0012] The effects of the invention

[0013] According to the present invention, an air flow measuring device can be provided that can suppress warping of the thin film portion and accurately measure the air flow rate when the air flow measuring element is mounted to the lead frame and a resin sealing package is formed to seal the air flow measuring element and the lead frame.

[0014] Further features of the present invention will become clear from the description and accompanying drawings. Furthermore, issues, configurations, and effects other than those described above will be clarified through the following description of embodiments. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of an internal combustion engine using an airflow measurement device.

[0016] Figure 2 A diagram illustrating the structure of an airflow measuring device. Figure 2 (a) is a top view. Figure 2 (b) and Figure 2 (c) is a side view. Figure 2 (c) is the main view.

[0017] Figure 3 This is the front view of the casing.

[0018] Figure 4 A diagram illustrating the structure of a resin-sealed encapsulation component. Figure 4 (a) is a 3D diagram. Figure 4 (b) represents Figure 4 A cross-sectional view of section AA of (a).

[0019] Figure 5 This is an enlarged cross-sectional view of a portion of the resin-sealed encapsulation.

[0020] Figure 6 An explanatory diagram illustrating the mechanism of bending stress in the package. Figure 6 (a) shows a cross-sectional view of an element with a convex thin film portion. Figure 6 (b) is a cross-sectional view of the element with a concave thin film portion. Figure 6 (c) is a table representing the symbols used in the calculation formulas to illustrate the mechanism.

[0021] Figure 7 A diagram illustrating the forces acting on components and lead frames due to the thermal shrinkage of the molding resin.

[0022] Figure 8 A diagram illustrating the warpage of the thin film portion. Figure 8 (a) is a schematic cross-section of the resin-sealed encapsulation. Figure 8(b) is a perspective view of the resin-sealed encapsulation component. Figure 8 (c) is a schematic diagram showing a cross-section of the thin film portion. Figure 8 (d) is an explanatory diagram illustrating the measurement of the longitudinal and transverse directions of the element.

[0023] Figure 9 The graphs are used to show the warpage of the thin film portion in the longitudinal and transverse directions of the element, the relationship between the transverse warpage and distance, and the relationship between the longitudinal warpage and distance.

[0024] Figure 10 A graph showing the relationship between the curing shrinkage rate and warpage of the resin. Figure 10 (a) is a graph showing the relationship between the curing shrinkage rate of the resin and the warpage of the film portion. Figure 10 (b) is a graph showing the relationship between the curing shrinkage rate of the resin and the warpage of the encapsulated part and the warpage of the film portion.

[0025] Figure 11 An explanatory diagram illustrating the warpage corresponding to the curing shrinkage rate of the resin-sealed encapsulation. Figure 11 Figure (a) shows the case where the curing shrinkage rate is 0.09%. Figure 11 (b) is a graph representing the case where the curing shrinkage rate is 0.3%.

[0026] Figure 12 Explanatory diagrams illustrating the various items and symbols of resin-sealed encapsulations, as well as the different thicknesses of the film portion relative to each item.

[0027] Figure 13 The graphs show the relationships between the curing shrinkage rate of the resin and the warpage of the film portion, the curvature and the warpage of the film portion, the radius of curvature and the warpage of the film portion, and the ratio of the upper mold resin to the lower side resin and the warpage of the film portion.

[0028] Figure 14 An explanatory diagram illustrating the radius of curvature of the component and the warpage of the thin film portion. Detailed Implementation

[0029] The specific embodiments described below (hereinafter referred to as embodiments) solve various problems that are expected to be solved in actual products, and in particular, solve various problems that are expected to be solved for use as air flow measuring devices for measuring air flow, and achieve various effects. One of the various problems solved by the following embodiments is described in the "Problem to be Solved by the Invention" section above; furthermore, one of the various effects achieved by the following embodiments is described in the "Effects of the Invention" section. The various problems solved by the following embodiments, as well as the various effects achieved by the following embodiments, will be described in the description of the embodiments below. Therefore, the problems solved and effects of the embodiments described below also include content beyond that in the "Problem to be Solved by the Invention" and "Effects of the Invention" sections.

[0030] In the following embodiments, the same reference symbol, even if the drawing number is different, indicates the same structure and has the same effect. For structures that have already been described, sometimes only the reference symbol is marked in the drawing and the description is omitted.

[0031] Referring to the accompanying drawings, an air flow measuring device 20 according to an embodiment of an internal combustion engine control system 1 using the air flow measuring device of the present invention in an electronic fuel injection manner will be described. Figure 1 As shown, the internal combustion engine control system 1 draws in intake air 2 from the air filter 21 according to the operation of the internal combustion engine 10, which includes engine cylinders 11 and engine pistons 12. The intake air 2 is then guided to the combustion chamber of the engine cylinders 11 via the intake air 22 having a main passage 22a, the throttle body 23, and the intake manifold 24. The flow rate of the intake air 2 guided to the combustion chamber is detected by the air flow measurement device 20 of the present invention. Based on the detected flow rate, fuel is supplied from the fuel injection valve 14 and guided to the combustion chamber as a mixture with the intake air 2. Furthermore, in this embodiment, the fuel injection valve 14 is provided at the intake port of the internal combustion engine. The fuel injected into the intake port forms a mixture with the intake air 2, which is then guided to the combustion chamber via the intake valve 15 for combustion to generate mechanical energy.

[0032] The fuel and intake air 2 guided into the combustion chamber are in a mixed state, and are ignited by the spark plug 13, resulting in explosive combustion and generating mechanical energy. The combusted gases are guided from the exhaust valve 16 to the exhaust pipe and discharged outside the vehicle as exhaust gas 3. The flow rate of the intake air 2 guided into the combustion chamber is controlled by the throttle valve 25, and the opening of the throttle valve 25 changes according to the operation of the accelerator pedal. By controlling the flow rate of the intake air guided into the combustion chamber, the fuel supply can be controlled. The driver controls the opening of the throttle valve 25 to control the flow rate of the intake air guided into the combustion chamber, thereby controlling the mechanical energy generated by the internal combustion engine.

[0033] The flow rate, temperature, humidity, and pressure of the intake air 2, which is introduced from the air filter 21 and flows in the main channel 22a, are detected by the air flow measuring device 20, and a signal indicating the flow rate of the intake air 2 is sent from the air flow measuring device 20 to the control device 4. Furthermore, the signal from the throttle angle sensor 26, which detects the opening of the throttle valve 25, is sent to the control device 4, and the signal from the rotation angle sensor 17 is also sent to the control device 4 to determine the position and state of the engine piston 12, intake valve 15, exhaust valve 16, and the engine speed. To determine the fuel-air mixture ratio based on the state of the exhaust gas 3, the signal from the oxygen sensor 28 is sent to the control device 4.

[0034] The control unit 4 calculates the fuel injection quantity and ignition timing based on the output of the air flow measuring device 20 (i.e., the flow rate of the intake air 2), the output of the rotation angle sensor 17, and the detected engine speed. Based on these calculations, it controls the amount of fuel supplied from the fuel injection valve 14 and the ignition timing by the spark plug 13. The fuel supply quantity and ignition timing are also precisely controlled based on the temperature detected by the air flow measuring device 20, the change in throttle angle, the change in engine speed, and the air-fuel ratio detected by the oxygen sensor 28. Furthermore, in the idling state of the internal combustion engine, the control unit 4 controls the engine speed by controlling the amount of air bypassing the throttle valve 25 using the idle air control valve 27.

[0035] The fuel supply and ignition timing, which are the main control quantities of an internal combustion engine, are calculated based on the output of the air flow measuring device 20. Therefore, improving the detection accuracy, suppressing time-varying variations, and enhancing the reliability of the air flow measuring device 20 are crucial for improving the control accuracy and ensuring the reliability of the vehicle.

[0036] In recent years, the demand for fuel efficiency and exhaust purification in vehicles has been extremely high. To meet these demands, improving the accuracy of the intake air flow rate measured by the air flow measurement device 20 is crucial. Furthermore, maintaining high reliability of the air flow measurement device 20 is also important.

[0037] Vehicles equipped with the airflow measurement device 20 are used in environments with large variations in temperature and humidity. Ideally, the airflow measurement device 20 also takes into account the response to temperature or humidity changes in the operating environment and the response to dust or pollutants.

[0038] Furthermore, the airflow measuring device 20 is installed on the intake manifold, which is affected by heat from the internal combustion engine. Therefore, the heat from the internal combustion engine is transferred to the airflow measuring device 20 via the intake manifold. The airflow measuring device 20 measures the flow rate of the intake air 2 by transferring heat with the intake air 2, so it is important to minimize the influence of external heat.

[0039] The airflow measuring device 20 installed in the vehicle not only solves the problems described in the "Problems to be Solved by the Invention" column and achieves the effects described in the "Effects of the Invention" column, as explained below, but also fully considers the aforementioned problems, solves various problems sought to be addressed in the product, and achieves various effects, as explained below. The specific problems solved and the specific effects achieved by the airflow measuring device 20 will be described in the following description of the embodiments.

[0040] <Overall Composition of the Air Flow Measurement Device>

[0041] like Figure 1 , Figure 2 of (a), Figure 2 (b) Figure 2 (c) and Figure 2 As shown in (d), the air flow measuring device 20 has a housing 100, a cover 200, and a chip package 300. The air flow measuring device 20 is inserted into the interior of the main channel 22a through a mounting hole provided on the channel wall of the gas inlet 22, and is used in a fixed state on the gas inlet 22.

[0042] like Figure 3 As shown, the housing 100 is constructed, for example, by injection molding of a synthetic resin material, and has a flange 111, a connector 112, and a measuring part 113. The flange 111 is used to fix the air flow measuring device 20 to the gas inlet 22. The connector 112 protrudes from the flange 111 and is exposed to the outside from the gas inlet 22 for electrical connection with external devices. The measuring part 113 extends from the flange 111 in a manner that protrudes toward the center of the main channel 22a.

[0043] like Figure 2 (b) Figure 2 (c) and Figure 2As shown in (d), the measuring section 113 is a thin, elongated shape extending straight from the flange 111, having a wide front side 121 and a back side 122, and a pair of narrow side sides 123 and 124. With the airflow measuring device 20 installed on the inlet gas 22, the measuring section 113 protrudes from the inner wall of the inlet gas 22 toward the center of the main channel 22a. Furthermore, the front side 121 and back side 122 are arranged parallel to the central axis of the main channel 22a. Of the narrow side sides 123 and 124 of the measuring section 113, the side 123 on the long side of the measuring section 113 faces each other on the upstream side of the main channel 22a, and the side 124 on the short side of the measuring section 113 faces each other on the downstream side of the main channel 22a. With the airflow measuring device 20 installed on the inlet gas 22, the top end of the measuring section 113 serves as the lower surface 125.

[0044] The measuring unit 113 has a secondary channel inlet 131 on side 123 and a first outlet 132 and a second outlet 133 on side 124. The secondary channel inlet 131, the first outlet 132, and the second outlet 133 are located at the top end of the measuring unit 113, which extends from the flange 111 toward the center of the main channel 22a. Therefore, gas near the central portion of the inlet gas 22 away from the inner wall surface can be introduced into the secondary channel. Thus, the air flow measuring device 20 can measure the flow rate of the gas in the portion of the inlet gas 22 away from the inner wall surface, thereby suppressing the reduction in measurement accuracy caused by the influence of heat, etc.

[0045] In the airflow measuring device 20, the measuring section 113 is shaped to extend long from the outer wall of the gas inlet 22 along an axis toward the center, while the widths of the side surfaces 123 and 124 are similar to... Figure 2 As shown in (d), it has a relatively narrow shape. Therefore, for the intake air 2, the air flow measuring device 20 can suppress the fluid resistance to a small value.

[0046] The measuring section 113 is inserted into the gas inlet 22 through a mounting hole. The flange 111 abuts against the gas inlet 22 and is fixed to it by bolts. The flange 111 has a generally rectangular shape in plan view, formed by a specified plate thickness, such as... Figure 2 As shown in (a), a pair of fixing holes 141 are provided at the corners of the diagonal. The fixing hole 141 has a through hole 142 through the flange 111. A fixing bolt (not shown) is inserted into the through hole 142 of the fixing hole 141 and screwed into the screw hole of the gas inlet 22, thereby fixing the flange 111 to the gas inlet 22.

[0047] like Figure 2As shown in (a), connector 112 has four external terminals 147 and correction terminals 148 inside. The external terminals 147 are terminals for outputting the measurement results of the air flow measuring device 20, i.e., physical quantities such as flow rate and temperature, and power supply terminals for supplying DC power to the air flow measuring device 20 for operation.

[0048] The correction terminal 148 is used to measure the air flow rate of the manufactured air flow measuring device 20, calculate the correction value related to each air flow measuring device 20, and store the correction value in the memory inside the air flow measuring device 20. In subsequent measurement operations of the air flow measuring device 20, the correction data representing the correction value stored in the memory is used, and the correction terminal 148 is not used.

[0049] Therefore, in order to prevent the correction terminal 148 from becoming an obstacle in the connection between the external terminal 147 and other external devices, the correction terminal 148 is designed to have a different shape than the external terminal 147. In this embodiment, the correction terminal 148 is shorter than the external terminal 147, so that even if the connection terminal of the external device to be connected to the external terminal 147 is inserted into the connector 112, it will not become an obstacle to the connection.

[0050] Furthermore, in the following explanation, such as Figure 3 As shown, the direction in which the measuring part 113 extends from the flange 111, i.e. the direction of the long side of the measuring part 113, is sometimes called the Z-axis; the direction in which the measuring part 113 extends from the secondary channel inlet 131 to the first outlet 132, i.e. the direction of the short side of the measuring part 113, is sometimes called the X-axis; and the direction in which the measuring part 113 extends from the front side 121 to the back side 122, i.e. the thickness direction of the measuring part 113, is sometimes called the Y-axis.

[0051] The housing 100 is provided with a sub-channel groove 150 for forming a sub-channel 134 and a circuit chamber 135 for housing a circuit board 311. The circuit chamber 135 and the sub-channel groove 150 are formed on the front side of the measuring section 113. The circuit chamber 135 is provided in a region on the X-axis direction (side 123 side) that is upstream of the flow direction of the intake air 2. The sub-channel groove 150 is provided across a region on the Z-axis direction top side (lower surface 125 side) of the measuring section 113 relative to the circuit chamber 135 and a region on the X-axis direction opposite to the circuit chamber 135 that is downstream of the flow direction of the intake air 2 (side 124 side).

[0052] The secondary channel 150 is covered by the cover 200 to form a secondary channel 134. The secondary channel 150 has a first secondary channel 151 and a second secondary channel 152 that branches off midway through the first secondary channel 151. The first secondary channel 151 is formed to span between the secondary channel inlet 131 on one side 123 of the measuring section 113 and the first outlet 132 on the other side 124 of the measuring section 113, and extends along the X-axis direction of the measuring section 113. The first secondary channel 151, in cooperation with the cover 200, forms a first secondary channel A that introduces intake air 2 from the secondary channel inlet 131 and returns the introduced intake air 2 from the first outlet 132 to the main channel 22a. The first secondary channel A has a flow path that extends from the secondary channel inlet 131 along the flow direction of the intake air 2 in the main channel 22a and connects to the first outlet 132.

[0053] The second auxiliary channel groove 152 branches off midway from the first auxiliary channel groove 151 and bends toward the base end (flange side) of the measuring section 113, extending along the Z-axis direction of the measuring section 113. Furthermore, it bends toward the other side (side 124 side) of the measuring section 113 in the X-axis direction from the base end of the measuring section 113 and makes a U-turn toward the top of the measuring section 113, again extending along the Z-axis direction of the measuring section 113. It then bends toward the other side (side 124 side) of the measuring section 113 near the first outlet 132, continuing to the second outlet 133 opened on the side 124 of the measuring section 113. The second outlet 133 is positioned downstream of the flow direction of the intake air 2 in the main channel 22a. The second outlet 133 has an opening area that is approximately equal to or slightly larger than that of the first outlet 132, and is formed at a position adjacent to the base end of the long side of the measuring section 113 relative to the first outlet 132.

[0054] The second sub-channel groove 152, in cooperation with the cover 200, forms a second sub-channel B through which the intake air 2, which branches off from the first sub-channel A, passes and is returned from the second outlet 133 to the main channel 22a. The second sub-channel B has a reciprocating flow path along the Z-axis direction of the measuring section 113. That is, the second sub-channel B has a forward channel section B1 and a return channel section B2. The forward channel section B1 branches off midway through the first sub-channel A and extends toward the base end side of the measuring section 113 (in the direction away from the first sub-channel A). The return channel section B2 turns back at the base end side of the measuring section 113 (the end opposite to the channel section) and makes a U-shaped turn, extending toward the top end side of the measuring section 113 (in the direction approaching the first sub-channel A). The return channel section B2 is connected to a second outlet 133, which opens in the downstream direction of the flow of the intake air 2 in the main channel 22a relative to the sub-channel inlet 131.

[0055] The second sub-channel B is positioned along the path to the channel section B1, where the chip package 300, described later, is located. The second sub-channel B is formed by extending back and forth along the long side of the measuring section 113, thus ensuring a longer channel length and reducing the impact on the chip package 300 in the event of pulsation within the main channel 22a.

[0056] The cover 200, like the housing 100, is formed by injection molding from a synthetic resin material and is installed on the side of the housing 100 to cover it. The cover 200 may also be formed from a metal material such as aluminum alloy by precision casting, for example, by lost-wax casting or die casting.

[0057] like Figure 4 of (a), Figure 4 (b) and Figure 5 As shown, the chip package 300 comprises an airflow measuring element (hereinafter referred to as the element) 301, a lead frame 302, a sealing resin component 303, a polyimide tape 304, and a chip adhesive film (hereinafter referred to as DAF) 305. The chip package 300 is manufactured by placing the element 301 and the lead frame 302 with the element 301 mounted in a mold, pouring molding resin into the mold, and thermosetting it.

[0058] The chip package 300 includes a sealing resin member 303, which has a generally rectangular flat plate shape when viewed from above. The sealing resin member 303 has a base portion disposed within the circuit chamber 135 of the housing 100 along its long side and a top portion disposed within the second secondary channel B of the housing 100 along its long side. Multiple terminal portions T are disposed at the base portion of the sealing resin member 303, protruding in directions opposite to each other along their short sides. Furthermore, a groove is recessed at the top portion of the sealing resin member 303, extending along its short side. The groove forms a channel Kt on the surface of the top portion of the sealing resin member 303 for the intake of air 2. The top portion of the sealing resin member 303 is disposed on... Figure 3 The housing 100 shown is formed within the forward channel section B1 of the second sub-channel B and the return channel section B2. The chip package 300 measures the flow rate of the intake air 2 flowing within the second sub-channel B and sends a signal of the measurement result to the control device 4.

[0059] like Figure 5As shown, the element 301 has an element body 401 that serves as a substrate. The element body 401 is composed of a flat, plate-like member and is joined to the lead frame 302 by means of a DAF 305 disposed between the back side and the lead frame 302. The surface of the element body 401 is exposed from the sealing resin member 303 as a detection section. The element body 401 has an opening Kd formed in such a way that it opens towards the back side, and a thin film section 402 is formed on the surface side of the element body 401 in such a way that it blocks the opening Kd. The thin film section 402 includes a first temperature difference sensor 407, a first heater temperature sensor 405, a heater 404, a second heater temperature sensor 406, and a second temperature difference sensor 408 arranged along the main flow direction of the measured medium, and is a detection section for detecting the flow rate of the measured medium. Hereinafter, the arrangement direction will be expressed as the transverse (short side direction), and the direction perpendicular to the arrangement direction will be expressed as the longitudinal (long side direction). The element 301 has a thin film portion 402 serving as a detection portion and a peripheral region portion 403 continuously extending around the thin film portion 402 on the surface of the element body 401.

[0060] The thin film portion 402 is, for example, composed of a thin film with a thickness of less than a few μm, exposed in the channel Kt of the sealing resin member 303. For example... Figure 8 As shown in (c), a first temperature difference sensor 407, a first heater temperature sensor 405, a heater 404, a second heater temperature sensor 406, and a second temperature difference sensor 408 are formed on the thin film portion 402. A PIQ layer 409 is formed around the upper side of the thin film portion 402. The thin film portion 402 can determine the flow rate of the intake air 2 flowing through the surface of the thin film portion 402 based on the temperature distribution along the direction of the surface of the thin film portion 402. The element body 401 has a frustum-shaped opening Kd formed on the back side of the thin film portion 402, with the opening diameter increasing the further away from the back side of the thin film portion 402.

[0061] In its standalone state before being molded by the sealing resin member 303, the element 301 has a flat surface shape with no curvature on the front and back sides of the element body 401. When the element 301 is molded together with the lead frame 302 by the sealing resin member 303, bending stress is generated due to the shrinkage of the resin between the sealing resin member 303 and the lead frame 302. During molding, changes occur in the cross-linking density and volume shrinkage between the molecules of the sealing resin member 303 during the curing process from the viscous fluid, so the volume decreases after curing.

[0062] Therefore, the so-called molding shrinkage rate is the shrinkage of the volume of the sealing resin component injected into the mold after cooling. The shrinkage rate (hereinafter referred to as shrinkage rate) is usually defined by the following formula (2).

[0063] [Formula 1]

[0064]

[0065] Furthermore, the JIS K6911 specification, derived from the accompanying mold conditions and the test piece conditions of the sealing resin component 303, is also expressed by the following formula (3). If the shrinkage ratio of the sealing resin component 303 is averaged by four measuring points with the mold size at room temperature set to D1, D2, D3, D4 and the molded part size at room temperature set to d1, d2, d3, d4, the shrinkage ratio of the sealing resin component 303 is obtained by the following formula (2).

[0066] [Formula 2]

[0067]

[0068] Furthermore, when component 301 is molded from sealing resin member 303, the surface of component body 401 deforms from a flat state to a convex, bent state. In this deformation, the radius of curvature ρ of the exposed portion of component 301 protruding from sealing resin member 303 is 2.13 or less. More specifically, the radius of curvature ρ (mm) of the peripheral region 403, excluding the thin film portion 402, on the surface of component body 401 is 0 or more. Figure 5 As shown, the chip package 300 is configured such that ρ ≤ 2.13 is satisfied along its long side. Figure 5 As shown, the upper surface of element 301 is specifically the boundary portion between element 301 and the sealing resin member 303 covering the upper surface of element 301. The radius of curvature ρ is represented by the following equation (1).

[0069] [Formula 3]

[0070]

[0071] In equation (1), such as Figure 5 As shown, h1 (mm) represents the thickness of the sealing resin member 303 relative to the lead frame 302 on the surface side and the back side of the sealing resin member opposite to the element 301, which is provided with the element 301 through the lead frame 302 (hereinafter referred to as the thickness of the back resin portion S), h2 (mm) represents the thickness of the lead frame 302 (mm), h3 (mm) represents the thickness of the sealing resin member 303 relative to the lead frame 302 on the surface side (hereinafter referred to as the thickness of the surface resin portion U), h4 (mm) represents the thickness of the element body 401, h5 (mm) represents the thickness of the film portion 402, and β (%) represents the curing shrinkage rate of the sealing resin member 303.

[0072] Furthermore, the radius of curvature ρ of the peripheral region 403 of the surface of the component body 401 can be measured by the following methods. Specifically, the chip package 300 is cut at the location of the component 301, thereby measuring the radius of curvature ρ of the surface of the component body 401 appearing on the cut surface. Alternatively, the radius of curvature ρ can be measured non-destructively using a non-contact displacement measurement method employing a laser beam or similar light. Furthermore, the radius of curvature ρ can also be measured non-destructively by scanning the peripheral region 403 of the surface of the component body 401 using a three-dimensional measuring instrument (also known as a 3D scanner).

[0073] The radius of curvature ρ is calculated using the general expression for the bending stress of the sealing resin component 303. Figure 6 (c) shows the calculation formula and the symbols for each item. In a general beam, if the Young's modulus is set as E, the second moment of the section is set as I, the bending moment is set as M, and ρ is set as the radius of curvature of the beam, then the following formula (a) can be obtained.

[0074] [Formula 4]

[0075]

[0076] like Figure 6 As shown in (a), when the thin film portion 402 is deformed into a convex shape, it becomes formula (b).

[0077] [Formula 5]

[0078]

[0079] like Figure 6 As shown in (b), when the thin film portion 402 is deformed into a concave shape, it becomes formula (c).

[0080] [Formula 6]

[0081]

[0082] In the laminated body that forms the sealing resin member 303 in the embodiment, the amount of warpage of the film portion 402 is determined by... Figure 6 The composite equilibrium of h1, h2, and h3 is shown in (c). Therefore, the apparent warping of h1 to h5 is determined.

[0083] Furthermore, when the curing shrinkage rate of the resin is set as β, β is related to the following equation (d).

[0084] [Formula 7]

[0085]

[0086] According to equation (d), equation (a) becomes equation (f).

[0087] [Formula 8]

[0088]

[0089] The bending moment M is represented by equation 9.

[0090] [Formula 9]

[0091] M=∑(h i ×α i ×ΔT)

[0092] =(h1+h3)α1×ΔT+h2×α2×ΔT+(h4+h5)α3×ΔT

[0093] = (h1×α1+h2×α2+h3×α1+h4×α3+h5×α3)

[0094] =ΔT{α1(h1+h3)+α2(h2)+(h4+h5)}

[0095] Here, if we set E, α, and ΔT of M to be dimensionless, we obtain the following equation (g).

[0096] [Formula 10]

[0097] EI∝∑(h i )=h1+h2+h3+h4+h5……(g)

[0098] Furthermore, the following equations (h) and (i) are obtained.

[0099] [Formula 11]

[0100]

[0101] EI∝∑(h i 3 )=h1 3 +h2 3 +h3 3 +h4 3 +h5 3 ……(i)

[0102] Here, if we set it as (h)(i)→(f), then we obtain the following equation (j).

[0103] [Formula 12]

[0104]

[0105] Therefore, based on the composite thickness γ of the chip package 300 of this embodiment, the warpage of the thin film portion 402 is determined to be 0 or ≤3μm in the case of the structure of this embodiment using Equation (a) of the curvature (1 / ρ) of the beam.

[0106] [Formula 13]

[0107]

[0108] Here, if γ is substituted into equation (j), it becomes equation 14.

[0109] [Formula 14]

[0110]

[0111] The general expression for curvature is obtained. The specific verification of this general expression will be described later.

[0112] The lead frame 302 is formed of a thin sheet of a highly conductive metallic material such as copper (Cu), and has a patterned portion (not shown) and Figure 4 Terminal T is shown in (a). Terminal T is connected to the terminal pads of the circuit board 311. Leadframe 302 supports and fixes component 301 across DAF 305. That is, component 301 is mounted on leadframe 302. Figure 5 As shown, a through-hole Kh is formed on the lead frame 302, which communicates with the opening Kd to the thin film portion 402, and a through-hole Ku is formed on the lead frame 302, which communicates with the opening K3 to the surface resin portion U described later. The through-hole Kh and the through-hole Ku are connected by a connecting channel R (see reference). Figure 4 (b)). The through-hole Kh, through-hole Ku, and connecting channel R function in such a way that the pressure inside the opening Kd of the thin film section 402 becomes approximately equal to the atmospheric pressure.

[0113] like Figure 4 (b) and Figure 5 As shown, the sealing resin member 303 has a back resin portion S of thickness h1 made of synthetic resin, also known as molding resin, and a surface resin portion U of thickness h3. The thickness h3 of the surface resin portion U is more than twice the thickness h1 of the back resin portion S. The sealing resin member 303 covers the element 301 and the lead frame 302 by means of the back resin portion S and the surface resin portion U, thereby making the various components a single unit. The molding resin is selected from materials with a curing shrinkage rate β of 0.18% or more. As long as the molding resin is a synthetic resin with a curing shrinkage rate β of 0.18% or more, the material of the resin is not particularly limited.

[0114] like Figure 4 and Figure 5As shown, a channel Kt is formed on the sealing resin member 303, exposing the film portion 402 and its surrounding area to allow airflow. Furthermore, a frustum-shaped opening (opening portion) K1, which increases in diameter the further away from the lead frame 302, is formed on the back resin portion S of the sealing resin member 303. The opening K1 is located on the side opposite to the element 301, separated from the lead frame 302. Furthermore, an opening K2 is formed on the surface resin portion U of the sealing resin member 303 at the end opposite to the channel Kt in the longitudinal direction of the sealing resin member 303. And, an opening K3 is formed on the back resin portion S of the sealing resin member 303 at the end opposite to the opening K1 in the longitudinal direction of the sealing resin member 303.

[0115] like Figure 4 (b) and Figure 5 As shown, the sealing resin member 303 has a groove-shaped channel Kt on its surface. The channel Kt of the sealing resin member 303 has a pair of channel walls Th and a bottom wall exposed on the surface of the element body 401. The pair of channel walls Th have a necking shape in which the opening area (cross-sectional area) of the channel Kt gradually narrows as it approaches the thin film portion 402, which serves as the detection part. In the sealing resin member 303, the pair of channel walls Th forming the channel Kt cover the edges on both sides of the element 301 in a direction orthogonal to the airflow passing through the channel Kt, and the surface resin portion U is formed such that the thin film portion 402 is exposed in the channel Kt. Therefore, when the sealing resin member 303 deforms due to thermal shrinkage, the element 301 is also subjected to stress from the surface resin portion U and deforms together with the sealing resin member 303.

[0116] Polyimide tape 304 is composed of a polymer compound containing imide bonds, and has high heat resistance, excellent mechanical properties, and resistance to chemicals. Polyimide tape 304 is disposed on the surface of lead frame 302 opposite to the surface on which component 301 is mounted, blocking the through holes Kh, through holes Ku, and connecting channels R of lead frame 302.

[0117] DAF 305 is made of a film adhesive material with high adhesion reliability and is sandwiched between component 301 and lead frame 302 to bond component 301 and lead frame 302 together. DAF 305 is provided with an opening that connects the opening Kd of film portion 402 and the through hole Kh of lead frame 302.

[0118] In the chip package 300 of this embodiment, the curing process during the formation of the sealing resin member 303 causes thermal shrinkage of the sealing resin member 303, resulting in warping of the film portion 402. The warping was specifically investigated. If the warping amount (mm) of the film portion 402 is large, the accuracy of the measurement of the intake air flow rate 2 decreases; therefore, a small warping amount of the film portion 402 is preferable. Hereinafter, with reference to the accompanying drawings, the warping amount of the film portion 402, the relationship between the film portion 402 and the curing shrinkage rate β, the radius of curvature ρ, and other factors will be specifically explained.

[0119] <The effect of thermal shrinkage of sealing resin component 303 and the warpage of film portion 402>

[0120] First, the effect of thermal shrinkage of the sealing resin member 303 and the warpage of the film portion 402 were specifically verified using Examples 1 and 2 and Comparative Examples 1 and 2 of the chip package 300 of this embodiment. Furthermore, the warpage (mm) of the film portion 402 refers to the height (mm) from the top of the convex shape of the film portion 402 after warping, based on the flat surface of the film portion 402 before warping.

[0121] like Figure 7 As shown, in the chip package of Comparative Example 1, the linear expansion coefficient α (ppm / ℃) of the lead frame 302 is 17.7, and an intermediate member 306 is sandwiched between the element 301 and the lead frame 302. The linear expansion coefficient α of the element 301 is 3, the linear expansion coefficient α of the package is 7, and the curing shrinkage rate β (%) of the molding resin is 0.11 or 0.3.

[0122] In the chip package of Comparative Example 2, the linear expansion coefficient α of the lead frame 302 is 17.7, there is no intermediate component between the element 301 and the lead 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 component 303 is 7, and the curing shrinkage rate β of the molding resin of the package is 0.11.

[0123] like Figure 7 As shown, in the chip package 300 of Embodiment 1, the linear expansion coefficient α of the lead frame 302 is 17.7, there is no intermediate component between the element 301 and the lead 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 component 303 is 7, and the curing shrinkage rate β of the molding resin of the sealing resin component 303 is 0.3.

[0124] The chip package 300 of Example 2 is the same as the air flow measuring device 20 of Example 1. The linear expansion coefficient α of the lead frame 302 is 17.7. There is no intermediate component between the element 301 and the lead 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 component 303 is 7. The curing shrinkage rate β of the molding resin of the sealing resin component 303 is 0.3.

[0125] like Figure 7 As shown, the inner diameter of the through hole Kh in the lead frame 302 of the chip package 300 of Embodiment 2 is larger than that in the chip package 300 of Embodiment 1.

[0126] In the chip package of Comparative Example 1, when the molding resin undergoes thermal shrinkage during curing, a compressive force (N) indicating (-) towards the center of element 301 and a tensile force (N) indicating (+) in the direction away from the center of element 301 act on the molding resin. Furthermore, the compressive force towards the center of element 301 acts on element 301, intermediate member 306, and lead frame 302. The chip package of Comparative Example 1 can withstand the compressive force generated by the shrinkage of lead frame 302 by means of intermediate member 306, thereby preventing the compressive force from lead frame 302 from accumulating on element 301.

[0127] In the chip package of Comparative Example 1, the compressive force acting on element 301 and intermediate member 306 is balanced with the tensile force acting on sealing resin member 303, and the force acting on film portion 402 is no longer present, thus eliminating warping of film portion 402. In Comparative Example 1, even if the curing shrinkage rate β of the molding resin is 0.11 or 0.3, regardless of its magnitude, the presence of intermediate member 306 suppresses the occurrence of warping of film portion 402.

[0128] In the chip package of Comparative Example 2, similar to Comparative Example 1, when the molding resin of the sealing resin member 303 undergoes thermal shrinkage during curing, a compressive force toward the center of the element 301 and a tensile force in the direction away from the center of the element 301 act on the sealing resin member 303. Furthermore, the compressive force toward the center of the element 301 acts on the element 301 and the lead frame 302. In Comparative Example 2, since no intermediate member is provided, the compressive force generated by the shrinkage of the lead frame 302 acts directly and accumulates on the element 301. Therefore, the compressive force acts on the thin film portion 402, resulting in a large warpage of the thin film portion 402.

[0129] In the chip package 300 of Example 1, as Figure 7As shown, when the molding resin of the sealing resin member 303 undergoes thermal shrinkage during curing, a relatively large compressive force toward the center of the element 301 and a relatively large tensile force toward the direction away from the center of the element 301 act on the sealing resin member 303. In addition, the compressive force toward the center of the element 301 acts on the element 301 and the lead frame 302.

[0130] As a result, the tensile force acting on the sealing resin member 303 is relatively greater than the compressive force acting on the element 301 and the lead frame 302, and the warpage of the sealing resin member 303 increases. When the warpage of the sealing resin member 303 increases, the relatively small compressive force acts on the film portion 402, and the warpage of the film portion 402 is reduced compared to Comparative Example 2. Therefore, it is known that by actively bending the element 301 backward in the stretching direction, the warpage of the film portion 402 will be reduced.

[0131] Similar to that in Example 1, when the molding resin of the sealing resin member 303 undergoes thermal shrinkage during curing, a relatively large compressive force toward the center of the element 301 and a relatively large tensile force in the direction away from the center of the element 301 act on the sealing resin member 303. In addition, the compressive force toward the center of the element 301 acts on the element 301 and the lead frame 302.

[0132] However, unlike Example 1, the through-hole Kh of the lead frame 302 in Example 2 is larger than that in Example 1, so the compressive force acting on the lead frame 302 is halved and relatively reduced. As a result, the tensile force acting on the sealing resin member 303 is relatively greater than the compressive force acting on the element 301 and the lead frame 302, and the warpage of the sealing resin member 303 increases. When the warpage of the sealing resin member 303 is large, the relatively small compressive force acts on the film portion 402, and the warpage of the film portion 402 is greatly reduced compared to Example 1. Therefore, it is known that by bending the element 301 further in the stretching direction, the warpage of the film portion 402 will be eliminated.

[0133] As is known from the results of Comparative Examples 1, 2, 1, and 2, when the sealing resin component 303 cools naturally from the molding temperature to room temperature, the difference in the coefficients of linear expansion α of each component causes the shrinkage, or recovery, of the lead frame 302 to be greater than that of the element 301, resulting in the film portion 402 being compressed and deformed. In this case, if the curing shrinkage rate β of the molding resin of the sealing resin component 303 is large, the compressive stress of the film portion 402 caused by the shrinkage of the lead frame 302 can be mitigated by the tensile force acting on the sealing resin component 303.

[0134] Therefore, stress is less likely to concentrate in the thin film portion 402, and deformation of the thin film portion 402 is suppressed. Compared with Comparative Example 2, the chip package 300 of Examples 1 and 2 applies tensile force to the element 301, so the warping of the thin film portion 402 caused by the compressive stress acting on the element 301, that is, the compressive force acting on the element 301, is reduced.

[0135] <Warpage amount in the transverse and longitudinal directions of thin film portion 402>

[0136] Next, the relationship between the lateral warpage (mm) and longitudinal warpage (mm) of the thin film portion 402 was specifically verified for the chip package 300 of this embodiment, which has the same intermediate component configuration as Comparative Example 1 described above and the same configuration as Embodiment 1 described above. In this verification, for Figure 8 The standard for determining the warpage (mm) of the thin film portion 402 of the chip package 300 shown in (a) is also the criterion for judging the allowable warpage. Furthermore, Figure 9 In the diagram, black dots represent chip packages 300 without intermediate components, while black squares represent chip packages with intermediate components. Furthermore, Figure 9 In the two columns of charts on the right, the chart on the left shows the lateral warping of the membrane, and the chart on the right shows the longitudinal warping of the membrane.

[0137] Regarding the transverse and longitudinal directions of the thin film section 402, as follows: Figure 8 (b) Figure 8 As shown in (d), the long side direction (x-axis direction) of the chip package 300, which is orthogonal to the flow direction of the intake air 2, is defined as the longitudinal direction, and the short side direction (z-axis direction) of the chip package 300, which is also the flow direction of the intake air 2, is defined as the transverse direction. Figure 9 As shown, when the lateral warpage of the thin film portion 402 is 10μm to 11μm, the longitudinal warpage of the thin film portion 402 also reaches 12μm to 14μm, both being large warpages. When the longitudinal warpage of the thin film portion 402 is 12μm to 14μm, the shape of the longitudinal warpage shows a double peak in the graph of warpage versus distance. Therefore, the thin film portion 402 bulges out, resulting in poor temperature distribution and compromised measurement accuracy.

[0138] Furthermore, when the lateral warpage of the thin film portion 402 is 7μm to 9μm, the longitudinal warpage of the thin film portion 402 also reaches 8μm to 12μm, both being large warpage amounts. When the longitudinal warpage of the thin film portion is 8μm to 12μm, the shape of the longitudinal warpage shows a double peak in the graph of warpage versus distance. Therefore, in this case, the thin film portion 402 also bulges out, resulting in poor temperature distribution and compromised measurement accuracy of the thin film portion 402.

[0139] Furthermore, when the lateral warpage of the thin film portion 402 is 4μm to 6μm, the longitudinal warpage of the thin film portion 402 also reaches 6μm to 8μm, both being relatively large warpage amounts. When the lateral warpage of the thin film portion 402 is 6μm to 8μm, in the graph of the relationship between warpage amount and distance, the lateral warpage shape of the thin film portion 402 exhibits a double peak, and in this case, the measurement accuracy of the thin film portion 402 cannot be obtained.

[0140] However, when the lateral warpage of the thin film portion 402 is 0.5 μm to 1 μm, the longitudinal warpage of the thin film portion 402 is 3 μm to 4 μm, both relatively small. In this case, regarding the relationship between warpage and distance, the warpage of the thin film portion 402 is small, resulting in a flat shape without peaks. Therefore, the shape of the thin film portion 402 becomes planar in both the lateral and longitudinal directions, resulting in good temperature distribution in both directions and achieving measurement accuracy.

[0141] Furthermore, in a configuration with an intermediate member, such as Comparative Example 1, the lateral warpage of the thin film portion 402 is 1.5 μm, and the longitudinal warpage is 2 μm, both relatively small. In this case, regarding the relationship between warpage and distance, the warpage of the thin film portion 402 is less, resulting in a flat graph without peaks. Consequently, the shape of the thin film portion 402 becomes planar in both the lateral and longitudinal directions, resulting in good temperature distribution in both directions and achieving measurement accuracy.

[0142] To ensure measurement accuracy, the warpage of the thin film portion 402 must be small, and the warpage shape must be flat rather than bimodal in the warpage versus distance graph in both the transverse and longitudinal directions. Figure 9 As shown, it is known that as long as the warpage of the thin film portion 402 is less than 3μm, the same level of precision as that of a chip package with intermediate components can be obtained.

[0143] <Curing shrinkage of molding resin and warpage of film portion 402>

[0144] Next, the relationship between the curing shrinkage rate of the molding resin of the sealing resin member 303 in the chip package 300 of this embodiment and the warpage of the thin film portion 402 was specifically verified. In this verification, [the following was conducted]: Figure 10 The optimal value of the curing shrinkage rate β of the molding resin is determined by the chip package 300 shown in (a).

[0145] like Figure 10As shown in (a), when the curing shrinkage rate of the resin is 0.3%, the warpage of the film portion 402 is 1.5 μm; when the curing shrinkage rate of the resin is approximately 0.14%, the warpage of the film portion 402 is approximately 3.2 μm; when the curing shrinkage rate of the resin is approximately 0.12%, the warpage of the film portion 402 is approximately 3.5 μm; when the curing shrinkage rate of the resin is approximately 0.11%, the warpage of the film portion 402 is approximately 3.9 μm; and when the curing shrinkage rate of the resin is approximately 0.09%, the warpage of the film portion 402 is approximately 4.2 μm.

[0146] As mentioned earlier, as long as the warpage of the thin film portion 402 is less than 3 μm, a level of precision equivalent to that of a chip package with intermediate components can be achieved. However, the four black dots, where the resin curing shrinkage rate is approximately 0.14% or less, exceed 3 μm. Furthermore, as... Figure 10 As shown in (a), when the dots marked with black dots are connected by dashed straight lines, the curing shrinkage of the resin is 0.18% and the warpage of the film portion 402 is 3 μm. Therefore, the optimal curing shrinkage of the resin is found to be 0.18% or higher.

[0147] <Relationship between the warping of the sealing resin component 303 and the warping of the film portion 402>

[0148] Next, the relationship between the warpage of the sealing resin member 303 and the warpage of the thin film portion 402 in the chip package 300 of this embodiment was specifically verified. For example... Figure 10 As shown in (b), the warping of the sealing resin member 303 indicates warping at the lower surface of the back resin portion S of the sealing resin member 303. Figure 10 In the graph shown in (b), Sample 1 is constructed in the same manner as in Example 1 described above, and Sample 2 is constructed in the same manner as in Example 2 described above. Furthermore, the warpage of the sealing resin member 303 is represented by a bar graph, and the warpage of the film portion 402 is represented by a broken line.

[0149] When the resin curing shrinkage rate is 0.09%, the warpage of the sealing resin component 303 in Sample 1 is approximately 5.2 μm, and the warpage of the film portion 402 is also approximately 5.2 μm. In Sample 2, the warpage of the sealing resin component 303 is approximately 5.8 μm, and the warpage of the film portion 402 is approximately 4.2 μm. When the resin curing shrinkage rate is 0.11%, the warpage of the sealing resin component 303 in Sample 1 is approximately 5.5 μm, and the warpage of the film portion 402 is approximately 4.8 μm. In Sample 2, the warpage of the sealing resin component 303 is approximately 5.5 μm, and the warpage of the film portion 402 is approximately 4.8 μm. When the shrinkage rate is 0.12%, the warpage of the sealing resin component 303 in Sample 2 is approximately 6.5 μm, and the warpage of the film portion 402 is approximately 3.5 μm. When the resin curing shrinkage rate is 0.14%, the warpage of the sealing resin component 303 in Sample 2 is approximately 6.6 μm, and the warpage of the film portion 402 is approximately 3.2 μm. When the resin curing shrinkage rate is 0.3%, the warpage of the sealing resin component 303 in Sample 1 is approximately 7.5 μm, and the warpage of the film portion 402 is approximately 2.2 μm. The warpage of the sealing resin component 303 in Sample 2 is approximately 7.8 μm, and the warpage of the film portion 402 is approximately 1.5 μm.

[0150] like Figure 10 As shown in (b), it was found that in Sample 1 and Sample 2, a structure without intermediate components can be used as long as the curing shrinkage rate of the resin is 0.18% or higher. Furthermore, it was found that as the curing shrinkage rate of the resin increases, the warpage of the sealing resin component 303 also increases; the curing shrinkage rate of the resin and the warpage of the sealing resin component 303 are proportional. It was also found that as the warpage of the sealing resin component 303 increases, the warpage of the film portion decreases; the warpage of the sealing resin component 303 and the warpage of the film portion 402 are inversely proportional. Furthermore, it was found that the increase in the curing shrinkage rate of the resin and the warpage of the sealing resin component 303 causes a tensile force to act on the element 301, resulting in a decrease in the warpage of the film portion 402.

[0151] <The relationship of warping in each component>

[0152] Next, the warpage relationship in each component of the chip package 300 of this embodiment was verified again. For example... Figure 11 As shown in (a), with a resin curing shrinkage rate of 0.09%, the warpage of the film portion 402 is 4.4 μm. It is known that when the warpage of the sealing resin member 303 is small, the warpage of the film portion 402 is large, showing an inverse relationship. Furthermore, as... Figure 11 As shown in (b), when the curing shrinkage rate of the resin is 0.3%, the warpage of the film portion 402 is 1.5 μm. It is known that when the warpage of the sealing resin member 303 is large, the warpage of the film portion 402 is small, and they are inversely proportional.

[0153] <Calculating specific numerical values ​​using general expressions>

[0154] Next, the specific values ​​of warpage in each component of the chip package 300 of this embodiment were verified by substituting the radius of curvature ρ of equation (1) into the thickness h5 of the thin film portion 402 as a parameter. Here, the warpage of the thin film portion 402 was determined by thermal stress analysis (from before cooling to after cooling). The specific values ​​and parameters used were... Figure 12 The values ​​recorded in the document. Furthermore, all parameters except h5 are set to fixed values. Regarding the calculated curvature 1 / ρ and radius of curvature ρ, when h5 is 0.0005, 1 / ρ is 0.461 and ρ is 2.168; when h5 is 0.001, 1 / ρ is 0.477 and ρ is 2.095; when h5 is 0.002, 1 / ρ is 0.491 and ρ is 2.037; when h5 is 0.0047, 1 / ρ is 0.505 and ρ is 1.980; and when h5 is 0.008, 1 / ρ is 0.509 and ρ is 1.983.

[0155] according to Figure 13 The relationship between the curing shrinkage rate β and the warpage of the film portion 402 was investigated, and the optimal values ​​were determined to be 3 μm or less for the warpage of the film portion 402 and 0.18% or more for the curing shrinkage rate β.

[0156] When the calculation results were verified based on these optimal values, it was found that the curvature 1 / ρ was greater than 0.47. It was also found that when the curvature 1 / ρ was converted to the radius of curvature ρ, the radius of curvature ρ was less than 2.13. Furthermore, it was found that the optimal ratio h3 / h1 of the thickness of the surface resin portion U to the thickness of the back resin portion S was greater than 2. Moreover, the optimal value for the curing shrinkage rate β was verified to be 0.18%.

[0157] <Experimental measurement of radius of curvature ρ>

[0158] Next, the radius of curvature ρ of the upper surface of element 301 in the chip package 300 of this embodiment was measured and verified to be consistent with the calculation result of the general expression. Figure 14 As shown, the measuring device used is a VR-3000 3D scanner. The measuring location is set to the oxide film area of ​​component 301, and the measuring method is to derive the radius of curvature ρ based on the exposed size of component 301 (the width of the channel for intake air 2).

[0159] Regarding the measurement results, such as Figure 14As shown in the graph, when the resin curing shrinkage rate β is 0.11%, ρ is 2.76 mm, and the corresponding warpage of the film portion 402 is approximately 4.8 mm. When the resin curing shrinkage rate β is 0.3%, ρ is 2.05 mm, and the corresponding warpage of the film portion 402 is approximately 1.5 mm. Therefore, the measured value of the radius of curvature ρ is verified to be consistent with the calculated result of the general expression.

[0160] The effects of the chip package 300 of this embodiment will now be explained. (1) The chip package 300 of this embodiment includes: a lead frame 302; an element 301, which is mounted on the lead frame 302 and has a thin film portion 402; and a sealing resin member 303, which seals the lead frame 302 and the element 301 with at least the thin film portion 402 exposed. Furthermore, it is characterized in that the radius of curvature ρ of the exposed portion of the element 301 exposed from the sealing resin member 303 is 2.13 or less.

[0161] The chip package 300 of this embodiment is formed such that the radius of curvature ρ (mm) of the exposed portion of the element 301 exposed from the sealing resin member 303 is 2.13 or less. Therefore, it is possible to suppress warping of the thin film portion 402 when forming the sealing resin member 303 that seals the element 301 and the lead frame 302. That is, by satisfying the condition that the radius of curvature ρ (mm) of the peripheral region of the surface of the element 301 after the molding resin forming the sealing resin member 303 is cured is 2.13 or less (ρ≤2.13), the warping of the thin film portion 402 is within an optimal value of 3 μm, thereby ensuring the flatness of the surface of the thin film portion 402 and obtaining a chip package 300 that can accurately measure the flow rate of the intake air 2.

[0162] Furthermore, in the chip package 300 of this embodiment, ρ satisfies the relationship of the following formula (1), so the effect of ρ≤2.13 can be reliably calculated by appropriately selecting h1~h5 of the chip package 300 and the curing shrinkage rate β.

[0163] [Formula 15]

[0164]

[0165] (2) Furthermore, in the chip package 300 of this embodiment, the curing shrinkage rate β of the molding resin forming the sealing resin member 303 is 0.18% or more. Therefore, when the sealing resin member 303 is naturally cooled from the molding temperature to room temperature, it can be actively deformed in a backward bending direction so that its surface becomes convex. Thus, the effect of easing the compressive stress of the film portion 402 caused by the shrinkage of the lead frame 302 by means of the tensile force acting on the molding resin is obtained, stress concentration in the film portion 402 is prevented, and deformation of the film portion 402 can be suppressed.

[0166] As a result, the same measurement accuracy as conventional chip packages that reduce warpage of the thin film portion 402 by providing an intermediate component to coordinate the coefficient of linear expansion α is achieved. Since the chip package 300 of this embodiment does not have an intermediate component, the production cost is reduced compared to conventional chip packages with intermediate components.

[0167] (3) Furthermore, in the chip package 300 of this embodiment, the sealing resin member 303 has a groove-shaped channel Kt, which has a pair of channel walls Th and a bottom wall exposed on the surface of the element body 401. The pair of channel walls Th forming the channel Kt of the sealing resin member 303 cover the edges of both sides of the element 301 in the direction orthogonal to the airflow, and the film portion 402 is exposed in the channel Kt. With this configuration, the following effect is obtained: when the sealing resin member 303 is naturally cooled from the molding temperature to room temperature, when the surface resin portion U of the sealing resin member 303 shrinks and deforms, the element 301 also deforms together with the surface resin portion U, and the tensile force acts on the film portion 402 to reduce the warpage of the film portion.

[0168] (4) Furthermore, in the chip package 300 of this embodiment, the thickness of the sealing resin member 303 on the surface side (element 301 side) relative to the lead frame 302, i.e., the maximum thickness (mm) h3 of the surface resin portion U, is formed at least twice the thickness of the sealing resin member 303 on the back side relative to the lead frame 302, i.e., the maximum thickness (mm) h1 of the back resin portion S. With this configuration, the following effect is obtained: when the sealing resin member 303 is naturally cooled from the molding temperature to room temperature, the surface resin portion U of the sealing resin member 303 effectively shrinks and deforms, exerting a tensile force on the film portion 402, thereby reducing the warpage of the film portion.

[0169] (5) Furthermore, in the chip package 300 of this embodiment, a through-hole Kh is formed in a portion of the lead frame 302 in the area where the thin film portion 402 is projected onto the lead frame 302 in a direction perpendicular to the surface of the element 301. A polyimide tape 304 is attached to the back side of the lead frame 302 to cover the through-hole Kh. With this configuration, a connecting channel R can be formed to the outside of the sealing resin member 303, thereby making the pressure acting on the thin film portion 402 equal to atmospheric pressure.

[0170] (6) Furthermore, in the chip package 300 of this embodiment, the sealing resin member 303 has an opening K1 in such a way that a portion of the tape 304 is exposed.

[0171] (7) Furthermore, the opening K1 is a truncated cone shape with a larger opening diameter the further away from the lead frame 302.

[0172] (8) The channel wall Th has a necked shape in which the opening area of ​​the channel Kt gradually narrows as it approaches the film part 402 (detection part).

[0173] (9) The resin-sealed encapsulation is manufactured by sealing with resin in such a way that the curing shrinkage rate β of the sealing resin component 303 is 0.18% or more.

[0174] (10) The resin-sealed package is manufactured by sealing the exposed portion of the element 301 exposed from the sealing resin member 303 with a curvature radius ρ of 2.13 or less.

[0175] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments, and various design changes can be made within the scope of the spirit of the invention as set forth in the claims. For example, the described embodiments are detailed descriptions made to illustrate the present invention in an easily understandable manner, and are not necessarily limited to having all the described configurations. Furthermore, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of one embodiment can be added to the configuration of another embodiment. Moreover, other configurations can be added, deleted, or replaced in a part of the configuration of each embodiment.

[0176] Symbol Explanation

[0177] 100…shell

[0178] 113… Measurement Department

[0179] 131…Secondary passage entrance

[0180] 134…Secondary Channel

[0181] 135…Circuit Room

[0182] 150… Secondary channel slot

[0183] 151…First Sub-channel Slot

[0184] 152…Second Sub-channel Slot

[0185] 300… Chip package (resin-sealed package)

[0186] 301… Component (Air Flow Measurement Component)

[0187] 302…lead frame

[0188] 303… Sealing resin components

[0189] 304… Polyimide tape

[0190] 305…DAF

[0191] 401…Component Body

[0192] 402… Thin Film Department (Inspection Department)

[0193] Kt…channel

[0194] Th…channel wall

[0195] ρ…radius of curvature

[0196] β…curing shrinkage rate.

Claims

1. An air flow measuring device comprising a resin sealing package, said resin sealing package having: Wireframe; An airflow measuring element, which is mounted on the lead frame, has a detection section; and A sealing resin component that seals the lead frame and the airflow measuring element with at least the detection portion exposed, characterized in that the airflow measuring device has... The radius of curvature ρ of the exposed portion of the airflow measuring element protruding from the sealing resin component is 2.13 mm or less. The lead frame has a hole formed in the area where the detection part is projected onto the lead frame in a direction perpendicular to the surface of the air flow measuring element. Tape is attached to the back side of the lead frame to cover the hole.

2. The air flow measuring device according to claim 1, characterized in that, The curing shrinkage rate β of the sealing resin component is 0.18% or higher.

3. The air flow measuring device according to claim 1, characterized in that, The sealing resin component has a groove-shaped channel, the channel having a pair of channel walls and an exposed bottom wall of the detection part. The pair of channel walls forming the resin-sealed encapsulation cover the edges on both sides of the airflow measuring element.

4. The air flow measuring device according to claim 3, characterized in that, The maximum thickness h3 of the sealing resin component relative to the lead frame on the side facing the air flow measuring element is more than twice the maximum thickness h1 of the sealing resin component relative to the lead frame on the back side.

5. The air flow measuring device according to claim 1, characterized in that, The sealing resin component has an opening in such a way that a portion of the tape is exposed.

6. The air flow measuring device according to claim 5, characterized in that, The opening is a truncated cone shape, with the diameter increasing the further away from the lead frame.

7. The air flow measuring device according to claim 3 or 4, characterized in that, The channel wall has a constricted shape, with the opening area of ​​the channel gradually narrowing as it approaches the detection unit.

8. A method for manufacturing a resin-sealed encapsulation, comprising placing an airflow measuring element and a lead frame to which the airflow measuring element is mounted into a mold, pouring molding resin for a sealing resin component into the mold and thermosetting it, thereby manufacturing the resin-sealed encapsulation, characterized in that... Resin sealing is performed with the curing shrinkage rate β of the sealing resin component being 0.18% or higher. The lead frame has a hole formed in the area where the detection part of the air flow measuring element is projected onto the lead frame in a direction perpendicular to the surface of the air flow measuring element. Tape is attached to the back side of the lead frame to cover the hole.

9. The method for manufacturing a resin-sealed encapsulation according to claim 8, characterized in that, The resin is sealed such that the radius of curvature ρ of the exposed portion of the airflow measuring element protruding from the sealing resin member is 2.13 mm or less.

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