JP2012079760A - Electronic circuit device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic circuit device which can enhance adhesion between a substrate and a resin sealing body, prevent short-circuit between conductors resulting from electromigration, and improve electrical reliability, while enabling a reduction in thickness and size, and also to provide a manufacturing method of the electronic circuit device.SOLUTION: An electronic circuit device comprises: a substrate 11 having insulating base materials 111 to 113 provided with conductors 115 to 118; electronic components provided on the substrate 11; a resin sealing body 17 covering the substrate 11 and the electronic components; and a resin coating 37 which is provided between an edge face 11C of the substrate 11 and the resin sealing body 17, and which has adhesion higher than that between the substrate 11 and the resin sealing body 17.

Description

  The present invention relates to an electronic circuit device and a manufacturing method thereof, and more particularly, to an electronic circuit device having a substrate in which a conductor is disposed on an insulating base material and sealing the substrate with a resin sealing body and a manufacturing method thereof.

  For example, a DC-DC converter is incorporated in a power supply unit of a general-purpose television. The DC-DC converter converts, for example, a DC voltage converted from a 100 V AC voltage for general home use into a DC voltage used for a control circuit unit, a drive circuit unit, and the like. The DC-DC converter finally generates a DC voltage of 12V or 24V.

  In developing general-purpose televisions such as liquid crystal televisions and plasma televisions that are becoming thinner and larger in screen, it is important to make power supply units thinner and smaller. Patent Document 1 below discloses an invention that is optimal for reducing the thickness and size of a power supply unit.

  The invention disclosed in Patent Document 1 is an electronic circuit device that includes a substrate, a transformer that employs a sheet transformer structure mounted on the substrate, and a resin sealing body that covers the substrate and the transformer. The board is a wiring board (circuit board) in which a conductor is formed on an insulating base material. Glass epoxy resin is used for the insulating base material. For example, Cu having excellent electrical conductivity such as copper is used for the conductor. Moreover, an epoxy resin is used for the resin sealing body, and this epoxy resin is molded using a transfer molding method. The electronic circuit device manufactured in this way is characterized in that it can be reduced in thickness and size because circuit elements such as a substrate and a transformer can be incorporated in one package.

JP 2010-1441077 A Japanese Patent Laid-Open No. 5-198948

  In the electronic circuit device disclosed in Patent Document 1 described above, the following points have not been considered. Prior to the development of electronic circuit devices used in harsh external environments exposed to high temperatures and high humidity such as roadsides and utility poles, a high-temperature, high-humidity bias test (life test) was performed on the electronic circuit devices. There has occurred. Specifically, the adhesion at the interface between the substrate of the electronic circuit device and the resin sealing body is not sufficient, and moisture enters the resin sealing body from the outside of the resin sealing body through the interface between the resin sealing body and the substrate. Intrusion occurred and electromigration occurred where conductive precipitates were deposited on the surface of the insulating base material of the substrate. In a substrate having a multilayer wiring structure in which a plurality of insulating base materials and conductors are alternately laminated, electromigration is also confirmed in the conductors between the laminated insulating base materials, and the interface between the insulating base materials is conductive. The body was deposited and a short circuit occurred between the conductors arranged close to each other through the end face of the substrate. When a short circuit occurs between the conductors, the electronic circuit device deteriorates in electrical reliability.

  Patent Document 2 discloses an invention relating to a thick film thin film hybrid multilayer circuit board in which a metal film is formed on the end surfaces of the upper and lower insulating layers and the interface between the upper and lower insulating layers is sealed using the metal film. Since the adhesion of the metal film is greater than the adhesion of the insulating layer, peeling of the interface between the upper and lower insulating layers can be prevented, and electromigration due to moisture intrusion can be prevented.

  However, in the invention disclosed in Patent Document 2, although electromigration due to moisture intrusion can be prevented, electromigration due to energization of a high voltage of about several hundred volts occurs, so the upper and lower insulating layers When the conductive precipitate generated at the interface of the metal contacts the metal film, a short circuit occurs between the conductors as described above.

  The present invention has been made to solve the above problems. Therefore, the present invention can improve the adhesion between the substrate and the resin sealing body while realizing a reduction in thickness and size, and can prevent a short circuit between the conductors due to electromigration. It is to provide an electronic circuit device capable of improving the performance.

  Furthermore, this invention is providing the manufacturing method which can manufacture the said electronic circuit apparatus easily.

  In order to solve the above-described problems, a first feature according to an embodiment of the present invention is that, in an electronic circuit device, a substrate in which a conductor is disposed on an insulating base, and an electronic component disposed on the substrate A resin encapsulant that covers the substrate and the electronic component, and a resin film that is disposed between the end surface of the substrate and the resin encapsulant and has higher adhesion than the adhesion between the substrate and the resin encapsulant. Is provided.

  In the electronic circuit device according to the first feature, the substrate has a multilayer structure in which a plurality of insulating base materials and conductors are alternately stacked, and the resin coating is formed from the end surface of the insulating substrate to the end surface of another insulating substrate. It is preferable that it is arrange | positioned over.

  In the electronic circuit device according to the first feature, the insulating base material of the substrate is composed of a glass fiber cloth impregnated with a thermosetting resin adhesive, and the resin coating is impregnated with a part of the glass fiber cloth for insulation. It is preferable that an impregnation region is formed at a part of the interface between the substrates.

  In the electronic circuit device according to the first feature, it is preferable that the impregnation dimension from the end surface of the insulating base material of the resin coating to a part of the interface is larger than the film thickness size on the end surface of the insulating base material of the resin coating. .

  In the electronic circuit device according to the first feature, the resin sealing body is made of orthocresol novolac epoxy resin, and the resin coating is made of any one of polyimide resin, fast-curing liquid epoxy resin, and siloxysan resin. It is preferable.

  According to a second aspect of the present invention, in the method of manufacturing an electronic circuit device, the step of forming a production substrate having a conductor on an insulating base and a plurality of substrate formation regions regularly arranged And forming a slit that exposes at least a part of the end surface of the insulating base material in a part between the substrate forming regions in the production substrate, and insulating the end surface of the insulating base material on the inner wall surface of the slit in the production substrate. A step of forming a resin film, and a step of cutting another part of the production substrate between the substrate formation regions to form a plurality of substrates from the cut substrate formation region of the production substrate.

  According to the present invention, it is possible to improve the adhesion between the substrate and the resin-encapsulated body while realizing a reduction in thickness and size, and to prevent a short circuit between the conductors due to electromigration. An electronic circuit device capable of improving the performance can be provided.

  Furthermore, according to this invention, the manufacturing method which can manufacture the said electronic circuit apparatus easily can be provided.

1 is a circuit system block diagram of an electronic circuit device according to an embodiment of the present invention. It is the top view (top view) which removed the resin sealing body of the electronic circuit device which concerns on one Example. It is the bottom view (bottom view) which removed the resin sealing body of the electronic circuit device shown in FIG. FIG. 4 is a side cross-sectional view of the electronic circuit device shown in FIGS. 2 and 3. FIG. 4 is an overall perspective view including a resin sealing body of the electronic circuit device shown in FIGS. 2 to 3. It is principal part sectional drawing of the board | substrate shown in FIG. It is an exploded perspective view of the 1st transformer of the electronic circuit device concerning one example. It is a top view of the production board | substrate in a 1st process explaining the manufacturing method of the electronic circuit apparatus which concerns on one Example. It is a top view of the production board | substrate in a 2nd process. It is a top view of the production board | substrate in a 3rd process.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic and different from actual ones. In addition, there may be a case where the dimensional relationships and ratios are different between the drawings.

  Further, the following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention specifies the arrangement of each component as follows. It is not what you do. The technical idea of the present invention can be variously modified within the scope of the claims.

  One embodiment of the present invention describes an example in which the present invention is applied to an electronic circuit device as a power supply module (intelligent power module: IPM) incorporated in a power supply unit used particularly in an external environment. Here, the electronic circuit device is a DC-DC converter.

[Electronic circuit system block configuration of electronic circuit device]
As shown in FIG. 1, an electronic circuit device 1 according to an embodiment is constructed with a DC-DC converter as one power supply module. The electronic circuit device 1 includes a transistor unit 2, a first transformer (main transformer) 3, capacitors 41, 42, 43 (electronic components), a diode (electronic component) 5, a control unit 6, a second transformer (for driving). A plurality of electronic components of the transformer 7 and the temperature detector 8 are provided. In the electronic circuit device 1, the input terminals Vin +, Vin-, the output terminals Vout +, Vout-, the DC voltage terminal DCIN, the switching signal terminal ON / OFF, the output voltage adjustment terminal TRM, the remote sensing terminals Vs +, Vs- are arranged. It is installed.

  The transistor section 2 includes a first insulated gate transistor (hereinafter simply referred to as an IGFET (Insulated Gate Field Effect Transistor)) 21, a second IGFET 22, and diodes 23 and 24. Here, IGFET is used in the meaning including both MOSFET (metal oxide semiconductor field effect transistor) and MISFET (metal insulated semiconductor field effect transistor). The transistor unit 2 is not limited to an IGFET as long as it has an equivalent function, and for example, an IGBT (insulated gate bipolar transistor), a bipolar transistor, or the like can be used.

  One end of the main electrode of the first IGFET 21 is connected to the input terminal Vin +, the other end of the main electrode is connected to one end of the main electrode of the second IGFET 22, and the gate electrode is connected to the second transformer 7. A diode 23 is provided in the reverse bias direction between one end and the other end of the main electrode of the first IGFET 21. The other end of the main electrode of the second IGFET 22 is connected to the input terminal Vin−, and the gate electrode is connected to the second transformer 7. A diode 24 is provided in the reverse bias direction between one end and the other end of the main electrode of the second IGFET 22. A capacitor 42 is inserted between the input terminals Vin + and Vin−.

  The first transformer 3 includes a primary winding (coil) 31, a secondary winding (coil) 32, and a core 33. One end of the primary winding 31 is connected to the output of the transistor unit 2, that is, the other end of the main electrode of the first IGFET 21 and one end of the main electrode of the second IGFET 22, and the other end is electrically connected in series with the capacitor 41. And connected to the input terminal Vin-. One end of the secondary winding 32 is connected to the output terminal Vout + with the diode 5 electrically connected in series, and the other end is connected to the output terminal Vout−.

  Between the output terminals Vout + and Vout−, each of the capacitor 43 and the temperature detecting unit 8 is electrically connected in parallel. The temperature detection unit 8 detects the temperature of the electronic circuit device 1 and outputs the detection result to the control unit 6. In the control unit 6, when a preset temperature rise is detected based on the detection result from the temperature detection unit 8, the control for stopping the operation of the transistor unit 2 through the second transformer 7, that is, this Control for stopping the operation of the electronic circuit system can be performed.

  Although not illustrated, the control unit 6 includes at least a control IC and a photocoupler. The control unit 6 controls the operation of the DC-DC converter of the electronic circuit device 1 based on a switching signal input from the switching signal terminal ON / OFF.

[Operation of electronic circuit device]
In the electronic circuit device 1 according to the embodiment shown in FIG. 1, first, a DC voltage before conversion is applied between the input terminals Vin + and Vin−, and further, a DC voltage, for example, 12V is supplied to the DC voltage terminal DCIN. A switching signal (activation signal) of the electronic circuit device 1 is given to the terminals ON / OFF. When the ON signal is given to the switching signal terminal ON / OFF, the control unit 6 performs the ON operation of the first IGFET 21 of the transistor unit 2 through the second transformer 7 and performs the OFF operation of the second IGFET 22. . When the ON operation of the first IGFET 21 is performed, a direct current flows from the transistor unit 2 (the other end of the main electrode of the first IGFET 21) to the primary winding 31 of the first transformer 3. When a direct current flows through the primary winding 31, a direct current is generated in the secondary winding 32 due to electromagnetic induction. This DC voltage is output as a DC voltage after conversion between the output terminals Vout + and Vout−.

  In the electronic circuit device 1 according to an embodiment, the DC voltage before conversion is, for example, 385V, and the DC voltage after conversion is, for example, 12V or 24V.

[Basic device structure of electronic circuit device]
The basic device cross-sectional structure of the electronic circuit device 1 according to one embodiment is as shown in FIGS. The electronic circuit device 1 is disposed on a substrate (circuit board) 11 having a first surface 11A and a second surface 11B opposite to the first surface 11A, and from the first surface 11A to the second surface 11B. And a stress buffer 91 made of a metal plate material and disposed facing the bottom surface of the magnetic body (the lower surface in FIG. 4 and the mounting surface side of the electronic circuit device 1). And a resin sealing body 17 that covers at least the magnetic body side of the substrate 11, the magnetic body, and the stress buffer 91.

  In one embodiment, the magnetic body of the electronic circuit device 1 is a ferromagnetic body that constructs the first transformer 3 or the second transformer 7 described above. The detailed structure of the first transformer 3 (and the second transformer 7) will be described later. In one embodiment, the magnetic body constructs the first transformer 3 and the second transformer 7. However, the present invention is not limited to this, and the magnetic body may construct a reactance, an inductor, and the like.

  In one embodiment, the stress buffer 91 has a function of reducing the stress exerted on the magnetic body by the thermal contraction of the resin sealing body 17, and further, the magnetic body (the first transformer 3 and the second transformer). 7) has a function of releasing heat generated from the resin sealing body 17 to the outside.

[Configuration of board (circuit board)]
As shown in FIGS. 2 to 4 and 6, particularly FIG. 6, the substrate 11 of the electronic circuit device 1 includes, in one embodiment, the first insulating base materials 111 and 112, the second insulating base material and the second insulating base material. A multilayer wiring board (multilayer circuit board) in which one conductor 115, 116 and second conductor 117, 118 are alternately stacked is used. A first conductor 115 is disposed on the surface of the first insulating base 111 which becomes the first surface 11A of the substrate 11 (the upper surface in FIGS. 4 and 6). On the surface (on the back surface) of the first insulating base material 112 that becomes the second surface 11B (the lower surface or the back surface in FIGS. 4 and 6) opposite to the first surface 11A of the substrate 11. A first conductor 116 is provided. The second insulating base 113 is disposed between the first insulating bases 111 and 112. A second conductor 117 is disposed on the surface of the second insulating base 113 on the first surface 11A side, and on the surface of the second insulating base 113 on the second surface 11A (back surface). A second conductor 118 is disposed on the top.

  The first conductors 115 and 116 both electrically connect terminals for mounting electronic components on the substrate 11 and electrically connecting them, between the electronic components, and between the electronic components and leads 180 described later. Functions as wiring and the like. Each of the second conductors 117 and 118 has a function of electrically connecting the first conductors 115 and 116.

  Here, the same conductive material is used for the first conductors 115 and 116 and the second conductors 117 and 118. For example, a metal foil or metal film having excellent conductivity such as Cu, Cu alloy, or Au is used for these conductors. When the first conductors 115 and 116 and the second conductors 117 and 118 are made of, for example, Cu foil, the film thickness is set to 20 μm to 80 μm, for example. In particular, in the first conductors 115 and 116, in order to improve bondability, a composite film in which, for example, a Ni plating film is formed on the surface of the metal foil or metal film can be used.

The first insulating bases 111 and 112 have at least an electrical insulating function and an adhesive function. In one embodiment, the first insulating bases 111 and 112 are not cured at the time of lamination, but are cured after lamination, for example, a glass fiber cloth impregnated with a thermosetting resin adhesive, a so-called prepreg. Is used. In the glass fiber cloth, for example, there are several single yarns having a diameter of 3 μm to 10 μm to which SiO ₂ is a main component and at least one of Al ₂ O ₃ , CaO, MgO, R ₂ O, B ₂ O _{3 and the} like is added. Ten to several hundreds are bundled and plain weave. For example, an epoxy resin is used as the thermosetting resin adhesive. The film thickness of the first insulating base materials 111 and 112 is set to 180 μm to 220 μm, for example.

  Similarly, the second insulating substrate 113 has at least an electrical insulating function and an adhesive function. In one embodiment, the second insulating base 113 is bonded to the second conductor 117 on the front surface and the second conductor 118 on the back surface, and is cured at this time. Already cured. As the second insulating base material 113, a glass fiber cloth impregnated with, for example, a thermosetting resin adhesive is used in the same manner as the first insulating base materials 111 and 112. The film thickness of the second insulating substrate 113 is set to 50 μm-70 μm, for example.

  Although not particularly described with reference numerals, the electrical connection among the first conductor 115, the second conductors 117 and 118, and the first conductor 116 is the same as that of the first insulating substrate 111. This is performed through connection hole wiring (through-hole wiring or via wiring) embedded in the connection holes provided in the second insulating base 113 and the first insulating base 112, respectively. For this connection hole wiring, a metal material such as Cu, Cu alloy, Au, etc., which is excellent in electrical conductivity and easy to manufacture in the semiconductor manufacturing process, is used. Further, in one embodiment, the substrate 11 includes a three-layer insulating base material including a first insulating base material 111, a second insulating base material 113, and a first insulating base material 112, a first conductor 115, The second conductors 117 and 118 and the four conductors of the first conductor 118 are provided, but the number of stacked layers is not limited thereto. That is, the substrate 11 is a single-layer wiring board provided with an insulating base material having the number of layers of one layer, two layers, four layers or more, and a conductor having the number of layers of one to three layers or five layers or more. Alternatively, it may be a multilayer wiring board.

  As shown in FIGS. 2, 3, 4, and 6, the substrate 11 configured in this manner has substantially the entire area of the side surface 11 </ b> C compared to the adhesion between the substrate 11 and the resin sealing body 17. A resin film 37 having high adhesion and insulating properties is disposed. Here, the substantially entire region refers to substantially the entire region around the substrate 11 and substantially the entire region in the thickness direction of the substrate 11 excluding at least the connecting portion 1103 disposed on the production substrate 1100 described in a later manufacturing method. Used in meaning. As a result, the resin coating 37 extends from the end face of the first insulating base 111 to the end face of the second insulating base 113 of the substrate 11 and further from the end face of the second insulating base 113 to the first insulation. It is disposed over the end surface of the substrate 112. On the side surface 11C of the substrate 11, the interface between the first insulating base 111 and the second insulating base 113 and the interface between the second insulating base 113 and the first insulating base 112 are covered with a resin film 37. Is called. Further, the resin film 37 is positively disposed particularly in a region where a sufficient distance from the side surface 11C of the substrate 11 cannot be secured.

  Further, the first insulating base materials 111 and 112 and the second insulating base material 113 of the substrate 11 are directed from the end surfaces where the resin coatings 37 are disposed to the inside, particularly from the end surfaces of the respective interfaces to the inside. In part, an impregnation region 37A in which a part of the resin coating 37 is impregnated with these insulating base materials is disposed. Here, as described above, since the glass fiber cloth is used for each of the first insulating base materials 111 and 112 and the second insulating base material 113, the impregnation region 37A has the resin coating 37 on the glass fiber cloth. It is comprised by impregnating a part of resin.

  In one embodiment, the resin coating 37 has an improved adhesion between the resin sealing body 17 and each of the first insulating base materials 111 and 112 and the second insulating base material 113 of the substrate 11 and each layer. A polyimide-based resin that can be impregnated at least in part of the interface between the insulating base materials is used mainly for bonding between the insulating base materials. This polyimide resin is applied to the end face of the insulating base material of each layer, and then heated for 1 hour at a temperature of 150 ° C., for example, to form a polyamic acid form. When the polyimide-based resin is used as an insulating material, for example, it is cured by heating for 2 to 6 hours at a high temperature of 250 ° C. to 350 ° C. to form a polyimide form. The impregnation effect is prioritized by utilizing the properties of heating and low viscosity.

  In FIG. 6, the film thickness t1 in the direction perpendicular to the side surface 11C of the substrate 11 of the resin coating 37 is set within a range of 1 μm to 5 μm, for example. At this time, the impregnation dimension (impregnation width) t2 in the direction perpendicular to the side surface 11C of the substrate 11 in the impregnation region 37A is set larger than the film thickness t1 of the resin coating 37, for example, within a range of 20 μm to 50 μm. it can.

  For the same purpose, for the resin film 37, for example, a fast-curing liquid epoxy resin having heat resistance can be used. At this time, the film thickness t1 of the resin coating 37 is set within a range of 5 μm to 20 μm, for example, and the impregnation dimension t2 of the impregnation region 37A can be set within a range of 10 μm to 30 μm, for example. Furthermore, a siloxane resin can be used for the resin film 37. An epoxy resin is used for the resin sealing body 17 to be described later. This epoxy resin is an ortho-cresol novolac epoxy resin, and since this epoxy resin contains a release agent, the substrate 11 Adhesion between the two is weak and an effective impregnation effect cannot be expected.

  In one embodiment, the substrate 11 is not necessarily limited to this numerical value, but has a rectangular planar shape in which the long side is set to 60 mm-62 mm, for example, and the short side is set to 42 mm-44 mm, for example. The thickness of the substrate 11 shown in FIGS. 4 and 6 is set to 0.8 mm to 1.6 mm, for example.

[Configuration of electronic components]
As shown in FIG. 2 and FIG. 4, on the first surface 11A of the substrate 11, as the electronic components, the transistor part 2, the first transformer (magnetic material) 3, the capacitor 42 described above in FIG. 43, a diode 5, a control unit 6, a second transformer (magnetic body) 7, a temperature detection unit 8, and the like are mounted. As shown in FIGS. 3 and 4, for example, a capacitor 41 or the like is mounted on the second surface 11 </ b> B of the substrate 11 as the electronic component described with reference to FIG. 1.

  As shown in FIGS. 1, 2, and 4, the transistor unit 2 includes a semiconductor device in which a semiconductor chip having a first IGFET 21 and a diode 23 is sealed with a resin sealing body, and similarly, a second IGFET 22 and a diode. And a semiconductor device in which a semiconductor chip having 24 is sealed with a resin sealing body. The transistor portion 2 is disposed on the first surface 11A on the lower right side of the peripheral region in FIG.

  The capacitor 42 is configured, for example, by sealing a capacitor body with a resin sealing body. In one embodiment, a glass epoxy resin can be practically used for the resin sealing body. The number of capacitors 42 to be mounted is not limited by the target capacitance value, but four capacitors 42 are arranged on the first surface 11A of the substrate 11 on the lower right side of the peripheral region in FIG. . The capacitor 43 is configured, for example, by sealing a capacitor body with a resin sealing body. Similarly, the number of capacitors 43 to be mounted is not limited by the target capacitance value, but six capacitors 43 are arranged on the lower left side of the peripheral region in FIG. Yes.

  The capacitor 41 is configured by sealing a capacitor body with a resin sealing body, for example, in the same manner as the capacitors 42 and 43 described above. The number of capacitors 41 is not limited by the target capacitance value, but four capacitors 41 are arranged on the second surface 11B of the substrate 11 on the lower left side of the peripheral region in FIG. The capacitor 41 is disposed at a position facing the position where the capacitor 42 is disposed.

  The diode 5 is configured, for example, by sealing a diode body, specifically a diode chip (semiconductor element) with a resin sealing body. The number of diodes 5 mounted is not limited by the intended rectification characteristics, but one diode 5 is disposed on the upper left side of the peripheral region in FIG.

  The control unit 6 includes a semiconductor device (control IC) 61 in which a semiconductor chip having a circuit for controlling at least the transistor unit 2 such as a transistor, a logic circuit, a resistor, and a capacitor is sealed with a resin sealing body, and a photocoupler 62. And 63, and is constructed. The semiconductor device 61 of the control unit 6 is arranged on the first surface 11A of the substrate 11 on the upper right side of the peripheral region in FIG. Photocouplers 62 and 63 are disposed on the upper left side in FIG. 2 on first surface 11A of substrate 11.

  The temperature detection unit 8 is disposed on the first surface 11A of the substrate 11 on the upper left side of the peripheral region in FIG. 2 and between the diode 5 and the photocouplers 62 and 63. The temperature detector 8 is disposed at a position away from the region where the diode 5 is disposed, so that the temperature detector 8 itself is prevented from being damaged or malfunctioning due to heat.

[Configuration of magnetic body (first transformer and second transformer)]
In the electronic circuit device 1 according to one embodiment, the first transformer 3 and the second transformer 7 are constructed of a magnetic material, specifically, a ferromagnetic material. As shown in FIGS. 2, 3, 4, and 7, the first transformer 3 is inserted and disposed in the opening 15 in the central region of the first surface 11 </ b> A of the substrate 11. In one embodiment, the opening 15 is configured as a through hole penetrating from the first surface 11 </ b> A of the substrate 11 to the second surface 11 </ b> B facing it.

  As shown in FIG. 7, in one embodiment, the first transformer 3 has a sheet transformer structure. Although a detailed description of the cross-sectional structure is omitted, the first transformer 3 includes a primary side winding 31 and a secondary side winding 32, and a transformer substrate 12 having a through hole in the central portion, It is disposed along the surface 12A (the surface 3A side of the first transformer 3), the back surface 12B (the surface 3B side) and the side surface 12C opposite to the surface 12A, and is also arranged in the central through hole 125 as a magnetic core of the toroidal core. And a core 33 provided.

  The transformer substrate 12 includes an insulating base 121 made of, for example, glass epoxy resin, and, for example, a conductor 122 that constructs the primary side winding 31 and the secondary side winding 32. For the conductor 122, a material having excellent conductivity such as Cu, Cu alloy, Au, or the like is used. In particular, the insulating substrate 121 is preferably made of a glass fiber cloth impregnated with a thermosetting resin adhesive as in the case of the substrate 11 described above.

The core 33 is a ferromagnetic body formed of, for example, a ferrite magnetic material obtained by sintering a metal oxide as a ceramic. As the metal oxide, for example, iron oxide (Fe ₂ O ₂ ) as a main component and a mixture of metal compounds such as manganese (Mn), magnesium (Mg), nickel (Ni), zinc (Zn), etc. are practical. Can be used for Alternatively, the core 33 may be formed of an amorphous magnetic material. The core 33 integrally constitutes and protrudes the magnetic core 331C, protrudes along both side surfaces 12C of the transformer substrate 12 around the magnetic core 331C, and is disposed on the back surface 12B side of the transformer substrate 12. (Lower core material) 331, and a second core (upper core material) 332 that is magnetically connected to the magnetic core 331C of the first core 331 and the protruding both sides, and is disposed on the surface 12A side of the transformer substrate 12. It has. The cross-sectional shape of the first core 331 is E-shaped, and since the cross-sectional shape of the second core 332 is a plate material and is I-shaped, the core 33 has an E-I core shape. In FIG. 7, the bottom surface of the first core 331 becomes the magnetic surface 3B, and the top surface of the second core 332 becomes the magnetic surface 3A. The core 33 may have an EE type core shape.

  The second transformer 7 has an induced electromotive force and an overall size smaller than those of the first transformer 3, but has a sheet transformer structure similar to the structure of the first transformer 3. Similarly to the method of mounting the first transformer 3 on the substrate 11, the second transformer 7 is mounted in a state of being inserted into the opening 16 provided in the substrate 11.

  The surface 7A of the core 73 of the second transformer 7 corresponds to the surface 3A of the core 33 of the first transformer 3 (both surfaces are surfaces in the same direction). Further, the back surface 7B facing the surface 7A of the core 73 corresponds to the surface 3B of the core 33 (both surfaces are surfaces existing in the same direction).

[Structure and properties of curable stress relieving material]
As shown in FIGS. 2 to 4, in the electronic circuit device 1 according to one embodiment, the side of the core 33 of the first transformer 3, that is, along two long sides and two short sides of the transformer substrate 12. At least the curable stress relieving material 35 is disposed on only the four side surfaces corresponding to the four side surfaces 12C and parallel to the four side surfaces 12C. Here, as shown in FIG. 4, the curable stress relaxation material 35 is not disposed on the upper surface 3 </ b> A and the lower surface 3 </ b> B of the core 33. The film thickness of the curable stress relaxation material 35 is set to be thinner as the distance from the side surface of the core 33 increases. The film thickness of the curable stress relaxation material 35 at the position (terminal) farthest from the side surface of the core 33 is substantially zero. The curable stress relieving material 35 disposed on the side surface of the core 33 of the first transformer 3 is extended to the connection region between the first transformer 3 and the substrate 11 on which the first transformer 3 is mounted, and the stress in this connection region. Contributes to a decrease in

In one embodiment, the curable stress relieving material 35 is, for example, a thermosetting adhesive liquid silicone rubber (thermosetting silicone resin) having white semi-fluidity. This heat-curable adhesive liquid silicone rubber has white semi-fluidity before curing, and has a viscosity of about 3.5 Pa · s-4.5 Pa · s at a temperature of 23 ° C., for example. The heat-curable adhesive liquid silicone rubber is applied by using a coating technique, a potting technique, etc., and then cured by heat treatment at 150 ° C. for 1 hour, for example. After curing, the heat curable adhesive liquid silicone rubber changes to a white rubber shape and has a hardness (type A) of, for example, 20-22, for example, 2.0 × 10 ^{−4 /} ° C.-2.2. It has a linear expansion coefficient of × 10 ^-4 / K.

  The curable stress relaxation material 35 is not limited to a thermosetting silicone resin. Any material that reduces the stress generated by the shrinkage of the resin sealing body 17 on the core 33 of the first transformer 3 may be an ultraviolet curable silicone resin (rubber), a room temperature curable silicone resin (rubber), or a thermosetting type. Any one of an ultraviolet curable epoxy resin and a room temperature curable epoxy resin can be used as the curable stress relaxation material 35. For example, a gel-type resin that is not curable flows out in the manufacturing process of the resin sealing body 17 using the transfer mold method, and it is difficult to reliably attach the gel-like resin to the side surface of the core 33.

[Lead structure]
As shown in FIGS. 2 to 5, leads (external terminals) 180 to 189 are arranged on one side surface (the lower side surface in FIGS. 2 and 3, the left side surface in FIG. 5) along the long side of the substrate 11. Leads 190 to 193 are arranged on the other side surface (the upper side surface in FIGS. 2 and 3 and the right side surface in FIG. 5) opposite to the one side surface. In these leads 180-193, the part inside the resin sealing body 17 is an inner part, and the part protruding outside the resin sealing body 17 is an outer part.

  The lead 180 is used as a DC voltage terminal DCIN. The lead 181 is used as a switching signal terminal ON / OFF. The lead 182 is used as the input terminal Vin +. The lead 183 is used as the input terminal Vin−. The lead 184 is used as the output terminal Vout−. The lead 185 is used as a negative remote sensing terminal Vs−. The lead 186 is an empty terminal NC. The lead 187 is used as an output voltage adjustment terminal TRM. The lead 188 is used as a positive remote sensing terminal Vs +. The lead 189 is used as the output terminal Vout−. The lead 186 used as the empty terminal NC has a function as a heat dissipation path in one embodiment.

  Leads 190-193 are empty terminals NC. The leads 190-193 used as the empty terminals NC similarly have a function as a heat dissipation path.

  The leads 180-193 are made of, for example, Cu or Cu alloy having excellent electrical conductivity. This conductive material has low thermal resistance and excellent thermal conductivity. The thickness of the leads 180-193 is set to 0.3 mm-0.5 mm, for example.

  The leads 180-193 are not labeled, but are electrically and mechanically connected to terminals arranged on the substrate 11 through an adhesive layer. For this adhesive layer, it is possible to use, for example, solder, paste or the like having a low thermal resistance and excellent thermal conductivity. For example, Sn-Ag-Cu solder can be used practically as the solder. Further, for example, an Ag paste used as a conductive paste can be used practically.

[Structure of stress buffer]
As shown in FIG. 3 to FIG. 5, the stress buffer 91 has the first core 331 of the core 33 of the first transformer 3 with the adhesive layer 4 interposed on the surface 91 </ b> A (the upper surface in FIG. 4). The lower surface 3B is bonded and attached to the first transformer 3. The stress buffer 91 is given to the core (magnetic body) 33 of the first transformer 3 along with the temperature contraction immediately after the resin sealing body 17 of the electronic circuit device 1 is molded by using, for example, a transfer molding method in the manufacturing process. It has a function of reducing stress by the rigidity of the stress buffer 91. That is, the stress buffer 91 has a function of repelling the compressive stress accompanying the thermal contraction of the resin sealing body 17, and effectively reduces the stress applied to the core 33. The stress buffer 91 is given to the core 33 accompanying the thermal expansion and thermal contraction of the resin sealing body 17 when it is generated by the temperature cycle of the temperature increase and the temperature decrease in actual operation after being completed as a product of the electronic circuit device 1. Has the function of reducing stress.

  In order to reduce the stress applied to the core 33 as much as possible and to reduce the thickness and size of the electronic circuit device 1, the stress buffer 91 has a size of the surface 91A and the size of the lower surface 3B of the core 33 facing the surface 91A. Is set as large as possible. Since the ratio of the stress buffer body 91 to the ratio of the resin sealing body 17 increases as the size of the stress buffer body 91 increases, the stress applied to the core 33 by the stress buffer body 91 can be reliably reduced. In other words, since the ratio of the resin sealing body 17 is reduced, the stress generation factor itself can be reduced. Further, the stress buffer 91 can improve the mechanical strength of the resin sealing body 17 that is particularly thinned.

The stress buffer 91 is made of a metal plate material, and this metal plate material has a moderate rigidity higher than that of the resin sealing body 17 and is much more thermally conductive than the resin sealing body 17. It is preferable to use, for example, a Cu (linear expansion coefficient: 1.7 × 10 ⁻⁶ ) plate or a Cu alloy plate that is excellent and close to the linear expansion coefficient of the core 33. This Cu plate or Cu alloy plate can be used as it is (in a pure state), but a plating film such as a Ni film may be formed on the surface.

  As shown in FIG. 4, the adhesive layer 4 has a function of electrically insulating the first transformer 3 and the stress buffer 91 in addition to a function of mechanically mounting the first transformer 3 and the stress buffer 91. In this embodiment, for example, a prepreg in which a glass fiber cloth is impregnated with a thermosetting adhesive is used for the adhesive layer 4. In addition, it replaces with the prepreg which impregnated the glass fiber cloth with the thermosetting adhesive, and the glass fiber cloth which apply | coated the thermosetting adhesive to both surfaces can be used for the contact bonding layer 4, for example.

[Structure of resin encapsulant]
As shown in FIGS. 2 to 5, in the electronic circuit device 1 according to one embodiment, the substrate 11 on which a plurality of electronic components are mounted is hermetically sealed by the resin sealing body 17 as described above. The resin sealing body 17 is formed by a transfer mold method. An electronic circuit device 1 according to an embodiment is a full-molded product using a DC-DC converter as one component. As described above, the resin sealing body 17 uses an ortho-cresol novolac epoxy resin containing a release agent.

  In the electronic circuit device 1 according to the embodiment, since the resin coating 37 is disposed on the side surface 12C of the substrate 11 as described above, the adhesion between the side surface 12C of the substrate 11 and the resin sealing body 17 is improved. Has been. Further, the resin film 37 is formed on the interface between the first insulating base 111 and the second insulating base 113 of the substrate 11 and part of the interface between the second insulating base 113 and the second insulating base 112. Since the impregnation region 37A impregnated with a part of the surface is generated, the adhesive force at the interface is improved. In the electronic circuit device 1 according to this example, even if a high-temperature and high-humidity bias test was performed and 1500 hours passed from the start of the test, a result of impairing electrical reliability was not obtained. The test conditions are a temperature of 85 ° C., a humidity of 85%, and an applied DC voltage of 500V. That is, the occurrence of a short circuit path due to the intrusion of moisture based on the deterioration of the adhesion between the substrate 11 and the resin sealing body 17, the invasion of moisture at the interface between the upper and lower insulating base materials of the substrate 11, etc. No short circuit occurred between adjacent conductors or between upper and lower conductors.

[Substrate manufacturing method]
The aforementioned substrate 12 is manufactured using the following manufacturing method.

  First, as shown in FIG. 8, a production substrate 1100 for manufacturing a plurality of substrates 11 at a time is manufactured. As shown in FIG. 6 described above, the production substrate 1100 sequentially stacks the first insulating base 112, the second insulating base 113, and the first insulating base 111 from the lower layer to the upper layer. Is formed. A first conductor 115 is bonded onto the surface of the first insulating base 111, and second conductors 117 and 118 are bonded onto both surfaces of the second insulating base 113, thereby A first conductor 116 is bonded on the surface of the substrate 112.

  Although not limited to the production number, in one embodiment, the production substrate 1100 has five substrate formation regions 1101 arranged in one direction. One substrate formation region 1101 corresponds to one substrate 11, and finally, a total of five substrates 11 are manufactured from one production substrate 1100.

  As shown in FIG. 9, an opening 15 for inserting the first transformer 3 and an opening 16 for inserting the second transformer 7 are formed in each substrate forming region 1101 of the production substrate 1100, and the substrate forming region 1101. A slit 1102 is formed in the other part of the periphery, leaving a part of the periphery in between as a connecting part 1103.

  Here, the slit 1102 is a slit that penetrates from the front surface of the production substrate 1100 to the back surface facing it, and is mainly manufactured to expose the side surface 11C and form the resin film 37 there. The slit 1102 is disposed in a region where a sufficient distance between the conductors of each layer and the substrate forming region 1101 cannot be secured, that is, a region where a short circuit path between conductors stacked vertically is short. The formation method of the slit 1102 is not particularly limited, but here the slit 1102 is formed by machining using a router. Here, the process of forming each of the slit 1102 and the openings 15 and 16 is the same manufacturing process, but both can be formed using different manufacturing processes.

  The connecting portion 1103 has a function of connecting the substrate forming regions 1101 to each other and forming the resin coating 37 on all the substrate forming regions 1101 of the production substrate 1100 in the same manufacturing process. The connecting portion 1103 is disposed in a region where a sufficient distance between each layer of conductors and the substrate forming region 1101 can be secured, that is, in a region where a short-circuit path between conductors stacked vertically is long. . If three or more connecting portions 1103 are provided for one substrate formation region 1101, it is possible to ensure mechanical strength against stress generated during the manufacturing process.

  As shown in FIG. 10, a resin film 37 is formed on the side surface 11 </ b> C corresponding to at least the inner wall of the slit 1102 of at least the production substrate 1100. Here, polyimide resin is used for the resin film 37 as described above. The polyimide resin is applied (coating) using a potting method, selectively formed using a mask manufactured by a photoresist technique, or applied by brushing. By forming the polyimide resin on the side surface 11C using the above-described conditions, it is formed as a resin film 37 as shown in FIG. 6, and a part of the insulating base material is impregnated into the impregnated region 37A. Form.

  Subsequently, between the respective substrate forming regions 1101 of the production substrate 1100, that is, the central portion of the slit 1102 and the connecting portion 1103 are cut, and a plurality of substrates 11 individually separated from the production substrate 1100 are manufactured. For example, a dicing cutter is used for cutting, and cutting is performed using mechanical processing.

[Characteristics of electronic circuit device]
In the electronic circuit device 1 according to the embodiment configured as described above, the resin film 37 is provided on the side surface 11C of the substrate 11 to improve the adhesion between the substrate 11 and the resin sealing body 17, and the substrate. 11 is provided with an impregnation region 37A in which a part of the resin film 37 is impregnated on the side surface 11C portion, so that a short circuit between conductors by electromigration due to moisture intrusion or the like is achieved while realizing a reduction in thickness and size. Can be prevented, and electrical reliability can be improved.

  Furthermore, in the manufacturing method of the electronic circuit device 1, the resin film 37 is formed on the side surface 11C of the substrate 11, and an impregnation region 37A can be formed by impregnating a part of the resin film 37 into the insulating base material. The electrical characteristics can be improved by a simple method.

(Other embodiments)
As described above, the present invention has been described by way of one embodiment and the second embodiment. However, the description and drawings which form part of this disclosure do not limit the present invention. The present invention can be applied to various alternative embodiments, examples, and operational technologies.

  For example, the present invention is not limited to a DC-DC converter as the electronic circuit device 1, but a power factor correction (PFC: Power Factor Correction) for constructing a DC-DC converter and a power supply module therewith in the preceding stage. The circuit may be the electronic circuit device 1.

  The present invention improves the adhesion between the substrate and the resin sealing body while realizing a reduction in thickness and size, can prevent a short circuit between the conductors due to electromigration, and improves electrical reliability. The present invention can be widely applied to electronic circuit devices that can be improved and manufacturing methods thereof.

DESCRIPTION OF SYMBOLS 1 ... Electronic circuit apparatus 11 ... Board | substrate 12 ... Transformer substrate 111, 112 ... 1st insulation base material 113 ... 2nd insulation base material 115, 116 ... 1st conductor 117, 118 ... 2nd conductor 1100 ... Production substrate 1101 ... Substrate formation region 1102 ... Slit 1103 ... Connection part 17 ... Resin sealing bodies 180-193, 1800-1808, 1900-1903 ... Lead 2 ... Transistor part 21 ... First IGFET
22 ... Second IGFET
DESCRIPTION OF SYMBOLS 3 ... 1st transformer 33 ... Core 37 ... Resin film 37A ... Impregnation area | region 4 ... Adhesion layer 41-43 ... Capacitor 5 ... Diode 6 ... Control part 7 ... 2nd transformer 8 ... Temperature detection part 91 ... Stress buffer

Claims (6)

A substrate having a conductor disposed on an insulating base;
An electronic component disposed on the substrate;
A resin encapsulant covering the substrate and the electronic component;
A resin coating disposed between an end face of the substrate and the resin sealing body, and having a high adhesiveness compared to an adhesiveness between the substrate and the resin sealing body;
An electronic circuit device comprising:   The substrate has a multilayer structure in which a plurality of the insulating base materials and the conductors are alternately stacked, and the resin coating is disposed from the end surface of the insulating substrate to the end surface of the other insulating substrate stacked thereon. The electronic circuit device according to claim 1, wherein the electronic circuit device is provided.   The insulating base material of the substrate is composed of a glass fiber cloth impregnated with a thermosetting resin adhesive, and the resin coating is partially impregnated into the glass fiber cloth to form an interface between the insulating substrates. The electronic circuit device according to claim 2, wherein an impregnation region is formed in the portion.   The impregnation dimension from the end surface of the insulating base material of the resin coating to a part of the interface is larger than the film thickness size of the resin coating on the end surface of the insulating base material. The electronic circuit device described.   The resin sealing body is made of orthocresol novolac epoxy resin, and the resin film is made of any one of polyimide resin, fast-curing liquid epoxy resin, and siloxysan resin. The electronic circuit device according to 1. A step of forming a production substrate having a conductor in an insulating base and a plurality of substrate formation regions regularly arranged;
Forming a slit in which at least a part of an end face of the insulating base material is exposed in a part between the substrate forming regions in the production substrate;
Forming an insulating resin film on the end surface of the insulating base material on the inner wall surface of the slit in the production substrate;
Cutting another part between the substrate formation regions in the production substrate, and forming a plurality of substrates from the cut substrate formation region of the production substrate;
A method of manufacturing an electronic circuit device, comprising: