magnetic sensor

Abstract

A magnetic sensor includes a chip land, a signal processing IC disposed opposite a first face of the chip land, an adhesive layer disposed between the first face of the chip land and a first face of the signal processing IC opposite the chip land, and at least one magneto-electric conversion element disposed opposite a first end face of the signal processing IC to detect a magnetic field in a specific direction. The chip land, the signal processing IC, the adhesive layer, and the at least one magneto-electric conversion element are sealed by a molding resin. At least a portion of the first end face of the signal processing IC is positioned on the at least one magneto-electric conversion element side relative to the first end face of the chip land on the at least one magneto-electric conversion element side in plan view. An isolation portion for entry of the molding resin is provided between the first face on the first end face side of the chip land and the first face on the first end face side of the signal processing IC, and the thickness of the isolation portion is smaller than the thickness of the chip land.

Description

Technical Field

[0001] This invention relates to a magnetic sensor. Background Technology

[0002] Patent Documents 1 and 2 disclose a current sensor having a magnetoelectric conversion element that detects current based on the magnetic flux density generated by the current.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 6415148

[0006] Patent Document 2: Japanese Patent No. 5695195 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In magnetic sensors with magnetoelectric conversion elements, it is desirable to reduce the influence of external noise.

[0009] Solution for solving the problem

[0010] A magnetic sensor according to one embodiment of the present invention comprises: a chip pad; a signal processing IC disposed opposite to a first surface of the chip pad; an adhesive layer disposed between the first surface of the chip pad and the first surface of the signal processing IC opposite to the chip pad; and at least one magnetoelectric conversion element disposed opposite to a first end face of the signal processing IC, the at least one magnetoelectric conversion element detecting a magnetic field in a specific direction. The chip pad, the signal processing IC, the adhesive layer, and the at least one magnetoelectric conversion element are sealed with molding resin. Alternatively, in a top view, at least a portion of the first end face of the signal processing IC may be located at a position closer to the at least one magnetoelectric conversion element side than the first end face of the chip pad on the at least one magnetoelectric conversion element side. Alternatively, an insulating portion for molding resin to enter may be provided between the first surface of the chip pad on the first end face side and the first surface of the signal processing IC on the first end face side, the thickness of the insulating portion being less than the thickness of the chip pad.

[0011] Alternatively, when viewed from above, the end face of the signal processing IC other than the first end face is positioned inside the chip pad compared to the end face of the chip pad other than the first end face.

[0012] Alternatively, the first surface of the signal processing IC, other than the first end face, can be directly bonded to the first surface of the chip pad via an adhesive layer.

[0013] Alternatively, the magnetic sensor may also include a conductor disposed around at least one magnetoelectric conversion element through which current flows.

[0014] It may be that the conductor has an opening, and at least one magnetoelectric conversion element is disposed within the opening.

[0015] It can be that at least one magnetoelectric conversion element is a magnetoelectric conversion element or multiple magnetoelectric conversion elements.

[0016] It is permissible that at least one magnetoelectric conversion element is a Hall element.

[0017] Furthermore, the above description of the invention does not list all the features of the invention. Additionally, sub-combinations of these feature groups can also constitute an invention. Attached Figure Description

[0018] Figure 1A This is a top view of the internal structure of the semiconductor package that functions as a magnetic sensor in the first embodiment.

[0019] Figure 1B yes Figure 1A A sectional view along line AA.

[0020] Figure 2 This is a diagram illustrating an example of a signal processing circuit containing a magnetoelectric conversion element for a magnetic sensor.

[0021] Figure 3A Is Figure 1B The figure shows an example of a stepped surface on the positive side of the z-axis direction of the end face of the pad of a signal processing IC chip.

[0022] Figure 3B Is Figure 1B The figure shows an example of a signal processing IC chip pad having a beveled edge on the positive side of the z-axis direction.

[0023] Figure 4A This is a figure showing the results of SEM cross-section observation near the upper end of the end face of the signal processing IC chip pad after a moisture absorption / reflow test during reliability testing, in the case where a slope is formed on the end face of the signal processing IC chip pad.

[0024] Figure 4B This is a figure showing the results of SEM cross-section observation near the upper end of the pad face of the signal processing IC chip after a moisture absorption / reflow test in a reliability test, where only the lead frame has been etched.

[0025] Figure 5A This is a top view of the internal structure of the semiconductor package that functions as a magnetic sensor in the second embodiment.

[0026] Figure 5B yes Figure 5A A sectional view along line AA.

[0027] Figure 6AIs Figure 5B The figure shows an example of a stepped surface on the positive side of the z-axis direction of the end face of the pad of a signal processing IC chip.

[0028] Figure 6B Is Figure 5B The figure shows an example of a signal processing IC chip pad having a beveled edge on the positive side of the z-axis direction.

[0029] Explanation of reference numerals in the attached figures

[0030] 1, 2, Magnetic sensor; 10, Molding resin; 11, Magnetoelectric conversion element chip pad; 12, Chip pad; 13, 14, Lead terminal; 15, Lead; 16, Primary conductor; 21, 21a, 21b, Magnetoelectric conversion element; 22, Signal processing IC; 31, 31a, 31b, 32, Chip mounting film; 41, 41a, 41b, 41c, 41d, 42, 141a, 141b, 142, Wire; 51, 52, End face; 55, Stepped surface; 5 6. Inclined surface; 57, 58. Isolation section; 61. Insulating film; 71a, 71b, 71c, 71d, 72a, 72b, 72c, 72d. Electrode pads; 81a, 81b, 81c, 81d, 82a, 82b, 82c, 82d. Wiring; 91. Magnetoelectric conversion section; 101. First potential; 102. Second potential; 105. Constant current source; 111, 112. Operational amplifier; 121, 122, 123. Resistors; 150. Instrumentation amplifier. Detailed Implementation

[0031] The present invention will now be described through embodiments thereof. These embodiments are not intended to limit the technical solutions described in the claims. Furthermore, the combinations of features described in the embodiments are not necessarily all necessary for the solution of the invention.

[0032] The following describes a magnetic sensor that has a magnetoelectric conversion element and outputs a signal corresponding to the magnitude of the magnetic field. A magnetoelectric conversion element is a component that converts the magnitude of the magnetic field input to the element into voltage or current and outputs it. Magnetoelectric conversion elements typically have weak output signals and poor temperature characteristics of magnetic sensitivity. Therefore, the magnetoelectric conversion element and a signal processing IC are encapsulated together in molding resin to form a semiconductor package. This signal processing IC includes signal processing circuitry that amplifies the output signal of the magnetoelectric conversion element and corrects the temperature characteristics of the magnetic sensitivity.

[0033] For example, Patent Document 1 discloses a current sensor consisting of a U-shaped primary conductor, a magnetoelectric conversion element disposed at the opening of the primary conductor, and a signal processing IC. The magnetoelectric conversion element detects the magnetic field generated by the current flowing through the primary conductor, and the signal processing circuit of the signal processing IC mounted on a large chip pad amplifies and outputs a signal corresponding to the magnitude of the current.

[0034] Furthermore, Patent Document 2 discloses a current sensor consisting of a signal processing IC and a primary conductor. In addition to signal processing circuitry, the signal processing IC also includes a magnetoelectric conversion element. The magnetoelectric conversion element, protruding from the chip pads, detects the magnetic field generated by the current flowing through the primary conductor, and the signal processing circuit amplifies and outputs a signal corresponding to the magnitude of the current.

[0035] However, in the current sensor described in Patent Document 1, the signal processing IC is disposed inside the chip pad, and the length of the wire connecting the signal processing IC and the magnetoelectric conversion element is increased, which can sometimes be affected by external noise. In particular, since a strong electric field or a high-frequency magnetic field is generated from the primary conductor, noise voltage can sometimes be induced in the wire due to electrostatic coupling or inductive coupling.

[0036] Furthermore, in the current sensor described in Patent Document 2, since the magnetoelectric conversion element is positioned separately from the primary conductor, the magnetic field generated by the current input to the magnetoelectric conversion element is sometimes significantly reduced, resulting in a significant decrease in sensitivity.

[0037] Furthermore, Patent Document 1 and Patent Document 2 did not take into account peeling or cracking that occurs within the semiconductor package.

[0038] Therefore, the magnetic sensor of this embodiment provides a small and highly sensitive magnetic sensor of excellent quality that reduces the influence of external noise and has no peeling or cracking.

[0039] Figure 1A and Figure 1B The structure inside the semiconductor package where the magnetic sensor 1 functions as described in the first embodiment is shown. Figure 1A This represents the top view, or upper surface view, as seen from the z-axis direction. Figure 1B yes Figure 1A A sectional view along line AA. (e.g.) Figure 1A and Figure 1B As shown, the magnetic sensor 1 includes, for example, molding resin 10, magnetoelectric conversion element chip pad 11, signal processing IC chip pad 12, lead terminal 13, magnetoelectric conversion element 21, signal processing IC 22, chip mounting films 31 and 32, and wires 41 and 42.

[0040] Regarding coordinates, Figure 1AIn this diagram, the direction parallel to the paper and moving upwards is defined as the x-axis, the direction parallel to the paper and moving from right to left is defined as the y-axis, and the direction perpendicular to the paper and moving from depth towards the front is defined as the z-axis. Any one of the x, y, or z axes is orthogonal to the other axes.

[0041] The magnetoelectric conversion element 21 detects a magnetic field in a specific direction, and the signal processing IC 22 amplifies the signal corresponding to the magnitude of the magnetic field and outputs the amplified signal from the lead terminal 13.

[0042] The magnetoelectric conversion element 21 is cut into a rectangle or square when viewed from above along the z-axis. The magnetoelectric conversion element 21 has a substrate made of silicon or a compound semiconductor and a magnetoelectric conversion section disposed on the substrate. The thickness of the substrate is adjusted by grinding the negative side surface along the z-axis. The substrate has a desired thickness in the range of 50 μm to 600 μm.

[0043] If the magnetic field in the z-axis direction is to be detected, then the Hall element is suitable as the magnetoelectric conversion element 21. Alternatively, if the magnetic field in any axis direction on the xy plane is to be detected, for example, if the magnetic field in the x-axis direction is to be detected, then a magnetoresistive element or a fluxgate magnetoresistive element is suitable as the magnetoelectric conversion element 21.

[0044] The signal processing IC 22 is cut into a rectangle or square shape when viewed from above. The signal processing IC 22 has a substrate made of silicon or compound semiconductor and signal processing circuitry disposed on the substrate. The thickness of the substrate is adjusted by grinding the negative side of the z-axis. The substrate has a desired thickness in the range of 50 μm to 600 μm. The signal processing circuitry includes circuitry that receives a small output signal corresponding to the magnitude of the magnetic field of the magnetoelectric conversion element 21 and at least amplifies the input signal.

[0045] Wire 41 electrically connects the electrode pads of the signal processing IC 22 to the electrode pads of the magnetoelectric conversion element 21. Wire 42 electrically connects the electrode pads of the signal processing IC 22 to the pads of the lead terminal 13. Furthermore, wires 41 and 42 are formed of a conductive material whose main components are Au, Ag, Cu, or Al.

[0046] The magnetoelectric conversion element chip pad 11, the signal processing IC chip pad 12, and the lead terminal 13 are formed from a lead frame made of a conductive material with Cu as the main component. The lead frame has a desired thickness in the range of 50 μm to 600 μm. The magnetoelectric conversion element chip pad 11 is a connection pad for mounting the magnetoelectric conversion element 21. The signal processing IC chip pad 12 is a connection pad for mounting the signal processing IC 22. When viewed from above, the signal processing IC chip pad 12 is C-shaped because a certain distance is required between the magnetoelectric conversion element chip pad 11 and the signal processing IC chip pad 12. The lead terminal 13 is a lead for supplying power and input / output signals to the signal processing circuit of the signal processing IC 22.

[0047] The chip mounting film 31 is an adhesive layer that bonds the magnetoelectric conversion element 21 to the chip pad 11 of the magnetoelectric conversion element. The chip mounting film 31 bonds the surface of the chip pad 11 of the magnetoelectric conversion element that is opposite to the magnetoelectric conversion element 21 and the surface of the magnetoelectric conversion element 21 that is opposite to the chip pad 11 of the magnetoelectric conversion element.

[0048] The chip mounting film 32 is an adhesive layer that bonds the signal processing IC 22 to the signal processing IC chip pad 12. The chip mounting film 32 bonds the side of the signal processing IC 22 opposite to the signal processing IC chip pad 12 and the side of the signal processing IC chip pad 12 opposite to the signal processing IC 22.

[0049] Chip mount films 31 and 32 have the same shape as the magnetoelectric conversion element 21 and the signal processing IC 22, respectively, when viewed from above. This is due to the manufacturing method; specifically, for chip mount film 32, when the substrate of the signal processing circuit mounted on the dicing tape is cut, the adhesive layer of the dicing tape is cut along with the signal processing IC 22 and adheres to the dicing tape side of the signal processing IC 22. The same applies to chip mount film 31. Chip mount films 31 and 32 can be made of either non-conductive or conductive resin. Epoxy resins are an example of non-conductive resins. Resins that are conductive can be made by mixing Ag filler into epoxy resins. Chip mount films 31 and 32 have a desired thickness in the range of 1 μm to 50 μm.

[0050] As the molding resin 10, for example, a thermosetting epoxy resin with added silica is used to form a semiconductor package by transfer molding. The molded molding resin 10 completely covers the magnetoelectric conversion element 21, the signal processing IC 22, the wire 41, and the wire 42.

[0051] At least a portion of the end face 51 of the magnetoelectric conversion element 21 side, which is the side closest to the magnetoelectric conversion element 21 among the four sides of the signal processing IC 22 (which is rectangular or square when viewed from above), is positioned outside the signal processing IC chip pad 12, relative to the end face 52 of the magnetoelectric conversion element 21 side. The magnetoelectric conversion element 21 is positioned opposite the end face 51 of the signal processing IC. As a result, the length of the wire 41 connecting the signal processing IC 22 and the magnetoelectric conversion element 21 is shortened. Therefore, the influence of unexpected external noise, such as noise voltage induced in the wire due to electrostatic coupling or inductive coupling, can be reduced. In addition, since the shape of the magnetic sensor 1 in the y-axis direction is reduced, the magnetic sensor 1 can be miniaturized.

[0052] Furthermore, when viewed from above, the three end faces of the magnetic sensor 1, excluding the end face 51 of the signal processing IC 22, are positioned closer to the inside of the signal processing IC chip pad 12 than the end face of the signal processing IC chip pad 12. Therefore, by pre-increasing the distance between the three end faces of the signal processing IC 22 and the end faces of the signal processing IC chip pad 12, the size of the signal processing IC 22 can be arbitrarily selected within the area of ​​the signal processing IC chip pad 12, allowing the same universal lead frame to be reused in various products with different signal processing methods.

[0053] Figure 2 This is a diagram illustrating an example of a signal processing circuit including a magnetoelectric conversion element 21 for a magnetic sensor 1. Regarding the reference numerals in the figure, those having... Figure 1A as well as Figure 1BComponents with the same function are labeled with the same reference numerals. Wire 41a electrically connects electrode pad 71a to electrode pad 72a, wire 41b electrically connects electrode pad 71b to electrode pad 72b, wire 41c electrically connects electrode pad 71c to electrode pad 72c, and wire 41d electrically connects electrode pad 71d to electrode pad 72d. Wiring 81a, 81b, 81c, and 81d electrically connect electrode pads 71a, 71b, 71c, and 71d to the magnetoelectric conversion unit 91. Wiring 82a electrically connects electrode pad 72a to the constant current source 105. Wiring 82b electrically connects electrode pad 72b to the non-inverting input terminal of operational amplifier 111. Wiring 82c grounds electrode pad 72c. Wiring 82d electrically connects electrode pad 72d to the non-inverting input terminal of operational amplifier 112. Resistors 121, 123, and 122 are connected in series. One end of resistor 121 is electrically connected to the output terminal of operational amplifier 111. The other end of resistor 121 is electrically connected to one end of resistor 123 and the inverting input terminal of operational amplifier 111. The other end of resistor 123 is electrically connected to one end of resistor 122 and the inverting input terminal of operational amplifier 112. The other end of resistor 122 is electrically connected to the output terminal of operational amplifier 112. Operational amplifiers 111 and 112, resistors 121, 123, and 122 constitute instrumentation amplifier 150.

[0054] The magnetoelectric conversion unit 91 of the magnetoelectric conversion element 21 is, for example, a Hall element. The magnetoelectric conversion unit 91 has two pairs of opposing terminals. One pair of opposing terminals is connected to electrode pads 71a and 71c via wirings 81a and 81c, respectively. The other pair of opposing terminals is connected to electrode pads 71b and 71d via wirings 81b and 81d, respectively.

[0055] The signal processing circuit of signal processing IC 22 has a first potential 101 and a second potential 102. A power supply potential is applied to the first potential 101, and a ground potential is applied to the second potential 102. The first potential 101 is connected to a constant current source 105 and is connected to an electrode pad 72a via wiring 82a. The second potential 102 is connected to an electrode pad 72c via wiring 82c. Additionally, the signal processing circuit of signal processing IC 22 includes an instrumentation amplifier 150. The instrumentation amplifier 150 consists of operational amplifiers 111 and 112 and three resistors 121-123. The instrumentation amplifier 150 amplifies the signals input to two input terminals and outputs them from two output terminals. The amplification rate of the instrumentation amplifier 150 is adjusted to the desired amplification rate by the three resistors 121-123. The two input terminals of the instrumentation amplifier 150 are connected to electrode pads 72b and 72d via wiring 82b and wiring 82d, respectively.

[0056] Wire 41a is connected to electrode pads 71a and 72a, wire 41b is connected to electrode pads 71b and 72b, wire 41c is connected to electrode pads 71c and 72c, and wire 41d is connected to electrode pads 71d and 72d.

[0057] A constant current is supplied from the constant current source 105 of the signal processing IC 22 to a pair of opposing terminals of the magnetoelectric conversion section 91 of the magnetoelectric conversion element 21. At this time, the other pair of opposing terminals of the magnetoelectric conversion section 91 generates an output voltage corresponding to the magnitude of the magnetic field input to the magnetoelectric conversion section 91. The output voltage of the magnetoelectric conversion section 91 is transmitted to the two input terminals of the instrumentation amplifier 150 via wires 41b and 41d.

[0058] Here, for wires 41b and 41d, when a strong electric field comes from the outside, electrostatic coupling occurs via parasitic capacitance, generating unexpected noise voltage. Furthermore, from the perspective of the two input terminals of the instrumentation amplifier 150, wires 41b and 41d form a closed loop with wiring 81b, wiring 82b, the magnetoelectric conversion unit 91, wiring 81d, and wiring 82d. Therefore, when a high-frequency magnetic field comes from the outside, inductive coupling occurs via the closed loop, generating unexpected noise voltage. The noise voltage generated by electrostatic and inductive coupling depends on the lengths of wires 41b and 41d; longer wires result in a larger noise voltage. Therefore, the shorter the lengths of wires 41b and 41d, the less impact from external noise is generated.

[0059] The signal processing circuit of the magnetic sensor 1, which includes the magnetoelectric conversion element 21, is not limited to this. The output voltage of the magnetoelectric conversion unit 91 can be amplified by using two inverting amplifiers instead of the instrumentation amplifier 150. Alternatively, the magnetoelectric conversion unit 91 can be supplied with a constant voltage instead of a constant current. Furthermore, switches can be inserted into the wiring 82a-82d to switch the drive of the magnetoelectric conversion unit 91.

[0060] Figure 3A and Figure 3B It is Figure 1B The image shows an enlarged view of the portion of the signal processing IC 22 that protrudes from the signal processing IC chip pad 12. Regarding the reference numerals in the figure, those with... Figure 1A as well as Figure 1B Components with the same function are labeled with the same reference numerals.

[0061] Figure 3AThis figure shows an example where a stepped surface 55 is provided on the positive side of the end face 52 in the z-axis direction of the signal processing IC chip pad 12. The stepped surface 55 is provided such that an isolation portion 57 for molding resin 10 to enter is formed between the surface of the signal processing IC chip pad 12 opposite to the signal processing IC 22 and the surface of the signal processing IC 22 opposite to the signal processing IC chip pad 12. The stepped surface 55 is also provided such that an isolation portion 57 for molding resin 10 to enter is formed between the chip mounting film 32 and the signal processing IC chip pad 12. The thickness D1 of the isolation portion 57 is less than the thickness D2 of the signal processing IC chip pad 12. The stepped surface 55 can be formed, for example, by a semi-cutting or imprinting process after etching the lead frame. Alternatively, it can be formed by etching after a semi-cutting or imprinting process on the lead frame. The formation of the stepped surface 55 is not limited to the methods described herein. If the thickness D2 of the signal processing IC chip pad 12 is 0.3 mm or more, the thickness D1 of the isolation portion 57 is preferably set in the range of 0.05 mm to 0.2 mm.

[0062] Figure 3B This figure shows an example where a bevel 56 is provided on the positive side of the end face 52 in the z-axis direction of the signal processing IC chip pad 12. The bevel 56 is formed between the surface of the signal processing IC chip pad 12 opposite to the signal processing IC 22 and the surface of the signal processing IC 22 opposite to the signal processing IC chip pad 12, providing an isolation portion 58 for the molding resin 10 to enter. The bevel 56 is also formed between the chip mounting film 32 and the signal processing IC chip pad 12, providing an isolation portion 58 for the molding resin 10 to enter. The thickness D1 of the isolation portion 58 is less than the thickness D2 of the signal processing IC chip pad 12. The bevel 56 can also be formed, for example, by stamping the lead frame. The formation of the bevel 56 is not limited to the method described herein. If the thickness D2 of the signal processing IC chip pad 12 is 0.3 mm or more, the thickness D1 of the isolation portion 58 is preferably set in the range of 0.05 mm to 0.2 mm.

[0063] Figure 4A and Figure 4B The results of SEM cross-section observation near the upper end of the end face 52 of the signal processing IC chip pad 12 after the moisture absorption / reflow test of the reliability test. Figure 4A This indicates the result of a magnetic sensor 1 having a bevel 56 formed on the end face 52 of the signal processing IC chip pad 12. Figure 4B This indicates the result for a magnetic sensor where only the lead frame underwent etching. Regarding the reference numerals in the figure, for those with... Figure 3A as well as Figure 3B Components with the same function are labeled with the same reference numerals.

[0064] exist Figure 4A In the signal processing IC chip pad 12, a bevel 56 exists on the positive side of the end face 52 in the z-axis direction. Molding resin 10 enters and adheres to the isolation portion 58 corresponding to the gap between the chip mounting film 32 and the bevel 56 of the signal processing IC chip pad 12. Therefore, the adhesion between the molding resin 10 and the signal processing IC chip pad 12 at the bevel 56 is enhanced, thus suppressing the moisture absorption and expansion of the chip mounting film 32 and thermal expansion at high temperatures, preventing peeling at the end face 52. On the other hand, in Figure 4B In the signal processing IC chip pad 12, there is no step surface 55 or inclined surface 56 on the positive side of the end face 52 in the z-axis direction. Figure 4B There is no isolation portion 57 or isolation portion 58 in the molded resin 10. Therefore, the molding resin 10 cannot suppress the moisture absorption and expansion of the chip mounting film 32 and the thermal expansion at high temperatures, resulting in peeling at the end face 52. Furthermore, slight cracks extending from the negative edge of the end face 52 in the z-axis direction toward the molding resin 10 are also generated, which are not shown. Based on the above, a magnetic sensor 1 can be provided by providing a stepped surface 55 or a slope 56, and by providing an isolation portion 57 or isolation portion 58 for the molding resin 10 to enter between the end face 52 side of the signal processing IC chip pad 12 opposite to the signal processing IC 22 and the side of the signal processing IC 22 opposite to the signal processing IC chip pad 12, thereby making the magnetic sensor 1 free from peeling and cracking and of excellent quality.

[0065] Furthermore, near the end face of the signal processing IC 22 other than end face 51, the molding resin 10 is directly bonded to the signal processing IC chip pad 12. Therefore, the adhesion between the molding resin 10 and the signal processing IC chip pad 12 is enhanced, thus suppressing moisture absorption and expansion of the chip mounting film 32 and thermal expansion at high temperatures, and also preventing peeling and cracking. Additionally, the end face of the signal processing IC 22 other than end face 51 is directly bonded to the signal processing IC chip pad 12 via the chip mounting film 32.

[0066] exist Figure 1A and Figure 1B In the diagram, when viewed from above, the signal processing IC chip pad 12 is C-shaped, but it can also be rectangular. Alternatively, the end face 51 of the signal processing IC 22 can be positioned outside the signal processing IC chip pad 12, relative to the end face 52 of the signal processing IC chip pad 12 facing the magnetoelectric conversion element 21.

[0067] Figure 5A and Figure 5B This shows the internal structure of the semiconductor package in the magnetic sensor 2 of the second embodiment. Figure 5A This is a top view, or upper surface view, taken from the z-axis direction. Figure 5B yes Figure 5AA sectional view along line AA. Regarding the reference numerals in the figure, those with... Figure 1A as well as Figure 1B The same reference numerals are used to indicate the same components. In addition, the magnetic sensor 2 has lead terminals 14, suspension leads 15, magnetoelectric conversion elements 21a and 21b, chip mounting films 31a and 31b, wires 141a and 141b, and an insulating film 61.

[0068] In the magnetic sensor 2 of the second embodiment, magnetoelectric conversion elements 21a and 21b detect a magnetic field in a specific direction generated by the current flowing through the lead terminal 14. The signal processing IC 22 amplifies the signal corresponding to the magnitude of the current, and the amplified signal is output from the lead terminal 13.

[0069] The lead terminal 14 has two terminals arranged such that current flows from one terminal to the other. A primary conductor 16 connected to the lead terminal 14 is positioned around magnetoelectric conversion elements 21a and 21b. The primary conductor 16, when viewed from above, has a shape that connects a C-shape and an inverted U-shape. Magnetoelectric conversion elements 21a and 21b are positioned at the openings of the C-shape and the inverted U-shape of the primary conductor 16, respectively. The current flowing through the primary conductor 16 generates a magnetic field around it corresponding to the magnitude of the current and the distance from the primary conductor 16. At the positions of magnetoelectric conversion elements 21a and 21b, a magnetic field with the largest z-axis component is generated. Because magnetoelectric conversion elements 21a and 21b are positioned within the openings, a higher sensitivity relative to the current can be obtained.

[0070] Here, when the current flowing through the primary conductor 16 is supplied in the direction of the arrow shown in the figure, a magnetic field is generated at the position of the magnetoelectric conversion element 21a in the positive direction of the z-axis, and at the position of the magnetoelectric conversion element 21b in the negative direction of the z-axis. The output voltages of the magnetoelectric conversion elements 21a and 21b are either positive and negative, or negative and positive. Therefore, if the signal processing circuit calculates the difference between the output voltages of the magnetoelectric conversion elements 21a and 21b, it obtains a signal corresponding to the magnitude of the current. On the other hand, for an external magnetic field, such as the Earth's magnetism, the output voltages of the magnetoelectric conversion elements 21a and 21b are either both positive or both negative, and thus cancel each other out by calculating the difference.

[0071] Magnetoelectric conversion elements 21a and 21b are cut into rectangles or squares when viewed from above. Both elements have a substrate made of silicon or a compound semiconductor and a magnetoelectric conversion section disposed on the substrate. The thickness of the substrate is adjusted by grinding the negative side of the z-axis. The substrate has a desired thickness in the range of 50 μm to 600 μm. Since a magnetic field in the z-axis direction is detected, a Hall element is suitable as the illustrated magnetoelectric conversion element. Alternatively, if the magnetoelectric conversion element is positioned to detect a magnetic field in any axial direction on the xy-plane, for example, if positioned to detect a magnetic field in the x-axis direction, a magnetoresistive element or a fluxgate magnetoresistive element is suitable as the magnetoelectric conversion element.

[0072] The signal processing IC 22 is cut into a rectangular or square shape when viewed from above. The signal processing IC 22 has a substrate made of silicon or compound semiconductor and signal processing circuitry disposed on the substrate. The thickness of the substrate is adjusted by grinding the negative side of the z-axis. The substrate has a desired thickness in the range of 50 μm to 600 μm. The signal processing circuitry of the signal processing IC 22 includes circuitry that receives a small output signal corresponding to the magnitude of the magnetic field of the magnetoelectric conversion element and at least amplifies the input signal. The signal processing IC 22 is configured not to overlap with the primary conductor 16 when viewed from above.

[0073] Wire 141a electrically connects the electrode pads of the signal processing IC 22 to the electrode pads of the magnetoelectric conversion element 21a, and wire 141b electrically connects the electrode pads of the signal processing IC 22 to the electrode pads of the magnetoelectric conversion element 21b. Wire 142 electrically connects the electrode pads of the signal processing IC 22 to the pads of the lead terminal 13. Furthermore, wires 141a, 141b, and 142 are formed of a conductive material whose main components are Au, Ag, Cu, or Al.

[0074] The signal processing IC chip pad 12, lead terminals 13 and 14, and suspension leads 15 are formed from a lead frame made of a conductive material with Cu as the main component. The thickness of the lead frame has a desired thickness in the range of 50 μm to 600 μm. The signal processing IC chip pad 12 is a connection pad for mounting the signal processing IC 22. The signal processing IC chip pad 12 is formed as a flat plate in the XY plane, configured so that it does not overlap with the primary conductor 16 when viewed from the positive Z-axis direction, but overlaps with at least a portion of the primary conductor 16 when viewed from the positive Y-axis direction. The lead terminals 13 are leads for supplying power or input / output signals to the signal processing circuitry of the signal processing IC 22. The suspension leads 15 are leads for supporting the molded resin 10 after molding during the assembly process.

[0075] The insulating film 61 is a rectangular strip when viewed from above. The insulating film 61 has an adhesive layer on its positive z-axis side. The insulating film 61 is configured such that a portion of the adhesive layer adheres to a portion of the negative z-axis side of the lead containing the signal processing IC chip pad 12, extending to the positions of magnetoelectric conversion elements 21a and 21b. The primary conductor 16 is stepped by a semi-punch-cut process to prevent contact between the insulating film 61 and the primary conductor 16. This step is selected in the range of 10 μm to 400 μm, depending on the lead frame thickness. The insulating film 61 is preferably made of a material capable of withstanding the high temperatures of the assembly process; therefore, polyimide resins are more suitable.

[0076] Chip mounting films 31a and 31b (31a not shown) are adhesive layers that bond magnetoelectric conversion elements 21a and 21b to the insulating film 61, respectively. Chip mounting film 32 is an adhesive layer that bonds the signal processing IC 22 to the signal processing IC chip pad 12. Chip mounting films 31a, 31b, and 32 have the same shape as magnetoelectric conversion elements 21a, 21b, and the signal processing IC 22 when viewed from above. Chip mounting films 31a, 31b, and 32 can be made of either non-conductive or conductive resin. Epoxy resins can be used for non-conductive applications. Resins that are conductive can be made by mixing Ag filler into epoxy resins. Chip mounting films 31a, 31b, and 32 have a desired thickness in the range of 1 μm to 50 μm.

[0077] As the molding resin 10, for example, a thermosetting epoxy resin with added silica is used to form a semiconductor package by transfer molding. The molded molding resin 10 completely covers the magnetoelectric conversion element 21a, magnetoelectric conversion element 21b, signal processing IC 22, wires 141a, wires 141b, and wires 142.

[0078] The end face 51 of the magnetic sensor 2, which is included in the signal processing IC 22 (which is rectangular or square when viewed from above) closest to the magnetoelectric conversion elements 21a and 21b, is positioned outside the signal processing IC chip pad 12 compared to the end face 52 facing the magnetoelectric conversion elements 21a and 21b. This shortens the lengths of the wires 141a connecting the signal processing IC 22 to the magnetoelectric conversion elements 21a and 21b, reducing unexpected external noise. Furthermore, the smaller size of the semiconductor package in the y-axis direction enables miniaturization of the magnetic sensor.

[0079] Furthermore, in this embodiment 2, when viewed from above, the other three end faces of the magnetic sensor 2, besides the end face 51 of the signal processing IC 22, are positioned closer to the inside of the signal processing IC chip pad 12 than the end face of the signal processing IC chip pad 12. Therefore, by pre-increasing the distance between the three end faces of the signal processing IC 22 and the end faces of the signal processing IC chip pad 12, the size of the signal processing IC 22 can be arbitrarily selected within the area of ​​the signal processing IC chip pad 12, allowing the same universal lead frame to be reused in various products with different signal processing methods.

[0080] An example of a signal processing circuit including magnetoelectric conversion element 21a and magnetoelectric conversion element 21b Figure 2 Similar to the above, except that a primary conductor 16 is disposed near conductors 141a and 141b. Since a strong electric field or a high-frequency magnetic field is generated from the primary conductor 16, the shorter the length of conductors 141a and 141b, the more the influence of external noise can be reduced.

[0081] Figure 6A and Figure 6B It is Figure 5B The image shows an enlarged view of the portion of the signal processing IC 22 that protrudes from the signal processing IC chip pad 12. Regarding the reference numerals in the figure, those with... Figure 3A , Figure 3B , Figure 5A as well as Figure 5B Components with the same function are labeled with the same reference numerals.

[0082] Figure 6A This diagram illustrates an example where a stepped surface 55 is provided on the positive side of the end face 52 in the z-axis direction of the end face 52 of the signal processing IC chip pad 12. (Compared to...) Figure 3ASimilarly, the stepped surface 55 is configured such that an isolation portion 57 for molding resin 10 to enter is formed between the surface of the signal processing IC chip pad 12 opposite to the signal processing IC 22 and the surface of the signal processing IC 22 opposite to the signal processing IC chip pad 12. The thickness D1 of the isolation portion 57 is less than the thickness D2 of the signal processing IC chip pad 12. The stepped surface 55 is configured such that an isolation portion 57 for molding resin 10 to enter is formed between the chip mounting film 32 and the signal processing IC chip pad 12. If the thickness D2 of the signal processing IC chip pad 12 is 0.3 mm or more, the thickness D1 of the isolation portion 57 is preferably set in the range of 0.05 mm to 0.2 mm.

[0083] Figure 6B This diagram shows an example where a bevel 56 is provided on the positive side of the end face 52 in the z-axis direction of the end face 52 of the signal processing IC chip pad 12. (Compared to...) Figure 3B Similarly, the inclined surface 56 is configured such that an isolation portion 58 for molding resin 10 to enter is formed between the surface of the signal processing IC chip pad 12 opposite to the signal processing IC 22 and the surface of the signal processing IC 22 opposite to the signal processing IC chip pad 12. The thickness D1 of the isolation portion 58 is less than the thickness D2 of the signal processing IC chip pad 12. The inclined surface 56 is configured such that an isolation portion 58 for molding resin 10 to enter is formed between the chip mounting film 32 and the signal processing IC chip pad 12. If the thickness D2 of the signal processing IC chip pad 12 is 0.3 mm or more, the thickness D1 of the isolation portion 58 is preferably set in the range of 0.05 mm to 0.2 mm.

[0084] and Figure 4A Similarly, in the magnetic sensor of Embodiment 2, where a bevel 56 is formed on the end face 52 of the signal processing IC chip pad 12 during the reliability test of the moisture absorption / reflow test, the adhesion between the molding resin 10 and the signal processing IC chip pad 12 at the bevel 56 is enhanced. Therefore, the moisture absorption expansion of the chip mounting film 32 and the thermal expansion at high temperatures can be suppressed, and no peeling occurs at the end face 52. On the other hand, in the magnetic sensor where only the lead frame has been etched, the molding resin 10 cannot suppress the moisture absorption expansion of the chip mounting film 32 and the thermal expansion at high temperatures, resulting in peeling at the end face 52. Furthermore, slight cracks extending from the negative edge of the end face 52 in the z-axis direction towards the molding resin 10 are also generated. Based on the above, a magnetic sensor 2 can be provided, which, by setting a stepped surface 55 or an inclined surface 56, provides an isolation portion 57 or an isolation portion 58 between the end face 52 of the signal processing IC chip pad 12 and the signal processing IC 22 for the molding resin 10 to enter, thereby making the magnetic sensor 2 free from peeling and cracks and of excellent quality.

[0085] Furthermore, near the end face of the signal processing IC 22 other than end face 51, the molding resin 10 is directly bonded to the signal processing IC chip pad 12. Therefore, the adhesion between the molding resin 10 and the signal processing IC chip pad 12 is enhanced, thus suppressing moisture absorption and expansion of the chip mounting film 32 and thermal expansion at high temperatures, and also preventing peeling and cracking. Additionally, the end face of the signal processing IC 22 other than end face 51 is directly bonded to the signal processing IC chip pad 12 via the chip mounting film 32.

[0086] exist Figure 5A and Figure 5B In the top view, the signal processing IC chip pad 12 is rectangular, but it can also be C-shaped. For the end face 51 of the signal processing IC 22, even a portion can be positioned outside the signal processing IC chip pad 12, beyond the end face 52 facing the magnetoelectric conversion element 21.

[0087] The present invention has been described above using various embodiments, but the scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. As can be seen from the claims, such modifications or improvements can also be included within the scope of the present invention.

[0088] It should be noted that the execution order of actions, sequences, steps, and stages in the apparatus, system, program, and method shown in the claims, specification, and drawings can be implemented in any order, unless specifically stated as "before" or "prior to," and as long as the output of a previous process is not used in a subsequent process. Even if terms such as "firstly" or "nextly" are used for convenience in describing the flow of actions in the claims, specification, and drawings, it does not mean that the actions must be performed in that order.

Claims

1. A magnetic sensor, comprising: Chip pads; A signal processing IC, which is configured opposite to the first side of the chip pads; An adhesive layer disposed between the first surface of the chip pad and the first surface of the signal processing IC opposite to the chip pad; and At least one magnetoelectric conversion element is disposed opposite to a first end face of the signal processing IC, the at least one magnetoelectric conversion element detecting a magnetic field in a specific direction. The chip pads, the signal processing IC, the adhesive layer, and the at least one magnetoelectric conversion element are sealed with molding resin. In this magnetic sensor, An isolation portion is provided between the first surface of the chip pad and the adhesive layer. The isolation portion has a stepped or inclined surface and opens at the first end face of the chip pad to allow the molding resin to enter. The thickness of the isolation portion is less than the thickness of the chip pad. When viewed from above, at least a portion of the first end face of the signal processing IC is located closer to the at least one magnetoelectric conversion element than the first end face of the chip pad with the opening of the isolation portion.

2. The magnetic sensor according to claim 1, wherein, When viewed from above, the end face of the signal processing IC other than the first end face is positioned inside the chip pad compared to the end face of the chip pad other than the first end face.

3. The magnetic sensor according to claim 2, wherein, The first surface of the signal processing IC, other than the first end face, is directly bonded to the first surface of the chip pad via the adhesive layer.

4. The magnetic sensor according to any one of claims 1 to 3, wherein, The magnetic sensor also includes a conductor disposed around the at least one magnetoelectric conversion element through which current flows.

5. The magnetic sensor according to claim 4, wherein, The conductor has an opening, and the at least one magnetoelectric conversion element is disposed within the opening.

6. The magnetic sensor according to any one of claims 1 to 3, wherein, The at least one magnetoelectric conversion element may be a plurality of magnetoelectric conversion elements.

7. The magnetic sensor according to any one of claims 1 to 3, wherein, The at least one magnetoelectric conversion element is a Hall element.

8. The magnetic sensor according to any one of claims 1 to 3, wherein, The thickness of the chip pad is 0.3 mm or more, and the thickness of the isolation portion is 0.05 mm or more and 0.2 mm or less.

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