JP2013120914A - Manufacturing method of circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a circuit device which enables a space below a circuit board to be resin sealed without causing voids.SOLUTION: In a manufacturing method of a circuit device of this invention, a gate 58 is provided at a lower mold 54 below a circuit board 14, and a sealing resin 16 is injected from the gate 58 into a cavity 56. In this structure, the sealing resin 16 injected from the gate 58 fills a small region below the circuit board 14 first and then reaches the entire cavity 56. Thus, the occurrence of voids in this region is prevented.

Description

  The present invention relates to a method for manufacturing a circuit device in which a circuit board having a circuit element incorporated on an upper surface is sealed with a resin.

  As a method for sealing a circuit board in which a hybrid integrated circuit including transistors and chip elements is incorporated on the upper surface, there are a sealing method using a case material and a resin sealing method using a resin.

  In the case of using the case material, the hybrid integrated circuit formed on the upper surface of the circuit board is accommodated in the hollow part of the case material by fitting the lid-like case material provided with the hollow part to the circuit board.

  When resin sealing is employed, the hybrid integrated circuit formed on the upper surface of the circuit board is covered by injection molding using a mold. With reference to FIG. 4A, the structure of the resin-encapsulated hybrid integrated circuit device 100 will be described. In the hybrid integrated circuit device 100, first, the upper surface of the circuit board 101 made of a metal such as aluminum is entirely covered with the insulating layer 102. A circuit element is connected to the conductive pattern 103 formed on the upper surface of the insulating layer 102 to constitute a predetermined hybrid integrated circuit. As elements disposed on the upper surface of the circuit board 101, a semiconductor element 105A and a chip element 105B connected by a thin metal wire 107 are illustrated. A lead 104 is fixed to the pad-like conductive pattern 103 at the end of the circuit board 101.

  The sealing resin 106 is a thermoplastic resin, and covers the upper surface, side surface, and lower surface of the circuit board 101. Here, in order to release heat generated from the circuit elements formed on the upper surface of the circuit board 101 to the outside through the circuit board 101, a sealing resin 106 that covers the lower surface of the circuit board 101 is used. Thinning is effective. However, if the thickness of the sealing resin 106 that covers the lower surface of the circuit board 101 is set to be as thin as, for example, about 0.5 mm, there arises a problem that the lower surface of the circuit board 101 is not partially covered with the sealing resin 106. This is because the gap between the lower surface of the circuit board 101 and the lower surface of the inner wall of the mold is narrowed in the step of injection molding the sealing resin 106 using a mold, and the sealing resin does not sufficiently reach the gap. Because.

  A method for avoiding this problem will be described with reference to FIG. 4B (Patent Document 1 below). Here, the injection molding is performed with the support member 110 supporting the circuit board 101 from the lower surface. Specifically, the support member 110 is made of a thermoplastic resin, and the inner surface has a size that contacts the lower surface and part of the side surface of the circuit board 101. Further, the outer surface of the support member 110 is in contact with the inner wall lower surface and side surfaces of the mold 112. Therefore, when the circuit board 101 supported by the support member 110 is stored in the cavity 114 of the mold 112, the support member 110 is positioned in the gap between the lower surface of the circuit board 101 and the lower surface of the inner wall of the mold 112. In this state, the circuit board 101 is resin-sealed by injecting a thermoplastic resin into the cavity 114. According to this method, since the support member 110 is located in the gap between the lower surface of the circuit board 101 and the lower surface of the inner wall of the mold 112, it is not necessary to inject liquid thermosetting resin into the gap. Generation of voids due to the lower surface of 101 not being partially covered is prevented. In addition, a potting resin 120 is formed on the upper surface of the circuit board 101 so as to cover the circuit elements in order to protect the fine metal wires and the like from the injection pressure during resin sealing.

Japanese Patent No. 3316449

  However, referring to FIG. 4B, when performing normal transfer molding with the support member 110 removed, the gate into which the sealing resin is injected into the cavity 114 is provided on the side of the circuit board 101. Therefore, the sealing resin injected into the cavity 114 from the side of the circuit board 101 flows preferentially above the circuit board 101, and the space below the circuit board 101 can be resin-sealed without voids. There was a difficult problem.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method of manufacturing a circuit device that enables resin-sealing of the space below the circuit board without voids. It is in.

  The method of manufacturing a circuit device according to the present invention includes a step of storing a circuit board having a circuit element mounted on an upper surface in a cavity of a mold, and sealing the circuit board by injecting a sealing resin into the cavity. Coating with resin, and in the coating step, the sealing resin is injected into the cavity from below the circuit board.

  According to the present invention, since the sealing resin is injected into the cavity from below the circuit board, even when the gap between the lower surface of the circuit board and the mold is thin, the sealing resin is surely filled into the gap. Thus, generation of voids can be suppressed.

It is a figure which shows the circuit apparatus manufactured with the manufacturing method of this invention, (A) is a perspective view, (B) and (C) are sectional drawings. It is sectional drawing which shows the manufacturing method of the circuit apparatus of this invention. It is a figure which shows the manufacturing method of the circuit apparatus of this invention, (A) is a top view which shows the mold metal mold | die used, (B) is the sectional drawing. It is a figure which shows the manufacturing method of the circuit device of background art, (A) is sectional drawing which shows the hybrid integrated circuit device manufactured, (B) is sectional drawing which shows the resin sealing process.

  A configuration of a hybrid integrated circuit device 10 to which the present exemplary embodiment is applied will be described with reference to FIG. 1A is a perspective view of the hybrid integrated circuit device 10, FIG. 1B is a sectional view taken along line BB ′ of FIG. 1A, and FIG. 1C is CC ′. It is sectional drawing in a line.

  In the hybrid integrated circuit device 10, a hybrid integrated circuit composed of a conductive pattern 22 and circuit elements is incorporated on the upper surface of the circuit board 14, and leads 24 electrically connected to the circuit are led out to the outside. Furthermore, the hybrid integrated circuit constructed on the upper surface of the circuit board 14, and the upper surface, side surfaces, and lower surface of the circuit board 14 are integrally covered with a sealing resin 16 made of a thermosetting resin.

  The circuit board 14 is a board made of a metal such as aluminum or copper, and its specific size is, for example, about vertical × horizontal × thickness = 61 mm × 42 mm × 1 mm. Here, a material other than metal may be employed as the material of the circuit board 14, and for example, ceramic or resin material may be employed as the material of the circuit board 14.

  The insulating layer 26 is made of an epoxy resin highly filled with a filler, and is formed so as to cover the entire surface of the circuit board 14.

  The conductive pattern 22 is made of a metal film such as copper having a thickness of about 50 μm, and is formed on the surface of the insulating layer 26 so as to realize a predetermined electric circuit. A pad made of the conductive pattern 22 is formed on the side from which the lead 24 is led out.

  The semiconductor element 28 and the chip element 30 (circuit element) are fixed to predetermined portions of the conductive pattern 22 through a bonding material such as solder. As the semiconductor element 28, a transistor, an LSI chip, a diode, or the like is employed. Here, the semiconductor element 28 and the conductive pattern 22 are connected via a thin metal wire 34. As the chip element 30, a chip resistor, a chip capacitor, or the like is employed, and electrodes at both ends are fixed to the conductive pattern 22 via a bonding material such as solder. Further, when the semiconductor element 28 is a power element that emits a large amount of heat, the semiconductor element 28 is fixed to the upper surface of the circuit board 14 via a heat sink made of a metal piece having a thickness of about several millimeters.

  The lead 24 is fixed to a pad provided in the peripheral portion of the circuit board 14 and functions as an external connection terminal through which an input signal and an output signal pass. Referring to FIG. 1B, a large number of leads 24 are provided along two opposing sides of the circuit board 14, but the leads 24 are arranged along one side or four sides. May be.

  The sealing resin 16 is formed by transfer molding using a thermosetting resin. In FIG. 1B, the conductive pattern 22, the semiconductor element 28, the chip element 30, and the fine metal wire 34 are sealed with the sealing resin 16. Further, the upper surface, the side surface, and the lower surface of the circuit board 14 are covered with the sealing resin 16.

  Further, referring to FIG. 1 (A), a fixing portion 19 is provided at an intermediate portion of the side surface of the sealing resin 16 facing in the left-right direction on the paper surface. The fixing portion 19 is a portion in which the side surface of the sealing resin 16 is recessed inward in a substantially semicircular shape in plan view, and a fixing means such as a screw is disposed in this portion, so that the lower surface of the sealing resin 16 Is brought into contact with a heat sink such as a heat sink.

  Referring to FIG. 1B, the thickness L1 of the sealing resin 16 covering the lower surface of the circuit board 14 is, for example, not less than 0.1 mm and not more than 0.3 mm. By thinning the sealing resin 16 covering the lower surface of the circuit board 14 in this way, the thermal resistance of the sealing resin 16 is reduced, and the heat generated from the semiconductor element 28 causes the circuit board 14 and the sealing resin 16 to move. It is released to the outside through

  As described in the problem column, it is not easy to cover the lower surface of the circuit board 14 with a normal transfer mold. However, in the present invention, sealing is performed from below the circuit board 14 in the transfer molding process as described later. By injecting the resin, the lower surface of the circuit board 14 is thinly coated with no voids.

  Next, a method for manufacturing a hybrid integrated circuit device having the above-described configuration will be described with reference to FIGS. FIG. 2 is a cross-sectional view showing a process for performing transfer molding, and FIG. 3 is a plan view showing a mold used in the transfer molding.

  In this step, first, a mold 50 including an upper mold 52 and a lower mold 54 used for transfer molding is prepared.

  The mold 50 includes an upper mold 52 and a lower mold 54, and a cavity 56 is formed by bringing both into contact. An eject pin 62 is disposed on the upper mold 52, and when the resin is injected into the cavity 56, the lower surface of the eject pin 62 is disposed on the same plane as the inner wall of the upper mold 52. And after hardening inside the cavity 56, the sealing resin is released by moving the eject pin 62 downward.

  On the other hand, in the lower mold 54, a gate 58 and a pod 61 are arranged in a portion corresponding to the lower part of the cavity 56. The position of the gate 58 is preferably below the center of the circuit board 14, so that the sealing resin 16 can be spread evenly throughout the cavity 56. Although only one gate 58 is provided here, a plurality of gates 58 may be provided below the circuit board 14. The pod 61 is disposed below the gate 58, and a tablet 59 made of a solidified thermosetting resin is disposed inside the pod 61, and the tablet 59 is pressed upward by a plunger 63.

  In this step, the mold 50 is heated to a temperature higher than the temperature at which the tablet 59 is melted.

  A specific sealing method is formed by first placing the circuit board 14 on which circuit elements such as semiconductor elements are arranged in the lower mold 54 and bringing the upper mold 52 into contact with the lower mold 54. The circuit board 14 is accommodated in the cavity 56. Further, the lead 24 fixed to both sides of the circuit board 14 is sandwiched between the upper mold 52 and the lower mold 54, thereby fixing the position of the circuit board 14 in the cavity 56.

  Here, in this step, since the liquid sealing resin 16 is injected from the gate 58 provided below the circuit board 14, the circuit board 14 moves upward by this injection pressure unless any countermeasure is taken. There is a risk. In this embodiment, the position within the cavity 56 of the circuit board 14 is fixed by holding the lead 24 between the upper mold 52 and the lower mold 54. Accordingly, even if the pressure that lifts the circuit board 14 is applied by injecting the sealing resin 16 from the gate 58, excessive movement of the circuit board 14 is suppressed. Further, in order to reliably prevent the circuit board 14 from moving, a contact pin that contacts the upper surface of the circuit board 14 from the inner wall of the upper mold 52 may be provided.

  Next, the tablet 59 put in the pod 61 is heated to obtain a liquid or semi-solid sealing resin 16. Thereafter, the plunger 63 is raised to inject the sealing resin 16 into the cavity 56 via the gate 58.

  The sealing resin 16 injected from the gate 58 first branches in the left-right direction on the paper and then flows toward the periphery of the circuit board 14 to fill the gap between the circuit board 14 and the inner wall of the lower mold 54. Is done. Next, the sealing resin 16 is filled in a region on the side of the sealing resin 16, and then the sealing resin 16 is filled in the region above the circuit board 14 to cover the circuit element.

  Air vents are provided at the left and right ends of the mold 50, and the air inside the cavity 56 is released to the outside through the air vent as the sealing resin 16 is injected.

  After the cavity 56 is sufficiently filled with the sealing resin 16, the sealing resin 16 made of a thermosetting resin such as an epoxy resin is sufficiently heated and cured, and then the upper mold 52 and the lower mold 54 are moved. Release. Further, by lowering the eject pin 62 downward, the upper surface of the sealing resin 16 is pressed downward, and the sealing resin 16 is separated from the inner wall of the upper mold 52.

  In this step, a gate 58 is provided in the lower mold 54 in a region below the circuit board 14, and the sealing resin 16 is injected from the gate 58 into the cavity 56. Therefore, even when the gap between the circuit board 14 and the lower mold 54 is very narrow, the sealing resin 16 injected from the gate 58 is first injected into this gap. This region is filled with the sealing resin 16 satisfactorily, and generation of voids is suppressed.

  With reference to FIG. 3 (A), the structure of the metal mold | die 50 used at the said process is further demonstrated. The mold 50 is provided with a plurality of cavities 56. Here, as an example, eight cavities 56 in 2 columns × 4 rows are provided in the mold 50, and the circuit board 14 is accommodated in each cavity 56. A gate 58 is provided below each circuit board 14.

  Referring to FIG. 3B, in this step, a pod 61 and a gate 58 for supplying sealing resin are provided below each cavity 56. By doing so, a predetermined amount of sealing resin can be sufficiently supplied to each cavity 56.

  After the above steps are completed, the hybrid integrated circuit device 10 shown in FIG. 1 is manufactured through a step of forming the lead 24 into a predetermined shape and length and a step of inspecting the characteristics of the built-in hybrid integrated circuit device. The

DESCRIPTION OF SYMBOLS 10 Hybrid integrated circuit device 14 Circuit board 16 Sealing resin 19 Fixed part 22 Conductive pattern 24 Lead 26 Insulating layer 28 Semiconductor element 30 Chip element 34 Metal fine wire 50 Mold 52 Upper mold 54 Lower mold 56 Cavity 58 Gate 59 Tablet 61 Pod 62 Eject pin 63 Plunger

Claims (5)

Storing a circuit board having circuit elements mounted on the upper surface in a cavity of a mold,
Coating the circuit board with the sealing resin by injecting a sealing resin into the cavity, and
In the covering step, the sealing resin is injected into the cavity from below the circuit board.   The sealing resin is injected into the cavity in a state where the distance between the lower surface of the circuit board and the inner wall of the mold is a predetermined length in the covering step. A method for manufacturing the circuit device according to 1.   The method for manufacturing a circuit device according to claim 1, wherein the gate into which the sealing resin is injected is disposed below a center portion of the circuit board.   The method for manufacturing a circuit device according to claim 1, wherein air inside the cavity is discharged to the outside from an air vent provided on a side of the cavity. The mold is provided with a plurality of the cavities,
5. The circuit device according to claim 1, wherein each of the plurality of cavities is provided with a gate into which the sealing resin is injected in a region corresponding to a lower portion of the circuit board. Production method.

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