JP2004363406A - Resin-sealed electronic component unit and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin-sealed electronic component unit in which a deformation due to a resin coating layer formed by insert molding can be suppressed, and to provide its manufacturing method. <P>SOLUTION: The resin-sealed electronic component unit is provided with a printed wiring board 4, an electronic component 5 mounted on the board 4, and a resin coating layer 3 for sealing the electronic component 5 by insert molding. The resin coating layer 3 is composed of a thermosetting resin where the temperature on the surface of the substrate during insert molding is lower than the melting point of solder being used for mounting the electronic component 5. The resin coating layer 3 is arranged on the surface and rear of a packaging printed wiring board 2 such that the quantity of thermosetting resin forming the resin coating layer 3 becomes substantially symmetric on the surface and rear of the board 2. The resin coating layer 3 has a shape copying the outline of the electronic component 5. Insert molding is performed by placing the board 2 in cavities 12a and 12b of such a shape as the quantity of thermosetting resin forming the resin coating layer 3 is arranged substantially symmetrically on the surface and rear of the board 2 and then injecting the thermosetting resin simultaneously to the surface and rear surface sides of the board 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a resin-sealed electronic component unit in which a printed wiring board on which electronic components such as semiconductors and LSIs are mounted is covered with a resin layer and sealed, and a method of manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a resin-sealed electronic component unit in which a printed wiring board on which electronic components such as semiconductors and LSIs are mounted is covered with a resin layer and sealed for waterproofing, moisture-proofing, or dust-proofing.
[0003]
As the resin-sealed electronic component unit, for example, there is one in which the entire printed wiring board on which electronic components are mounted is covered with a resin such as an epoxy resin. Such a resin-sealed electronic component unit is manufactured by housing the printed wiring board in a case and injecting an epoxy resin into the case (for example, see Patent Document 1).
[0004]
Since the epoxy resin has excellent environmental resistance and good adhesion and adhesion to the printed wiring board, the resin-sealed electronic component unit is excellent in performance against water, moisture and dust. However, since the epoxy resin is thermosetting, it needs to be maintained at a temperature of 100 ° C. or more for several hours after being poured into the case, resulting in low work efficiency and an inevitable increase in size of the equipment. There is.
[0005]
In the case of manufacturing as described above, the height of the tallest component among the electronic components mounted on the printed wiring board is injected to inject resin into the case in which the printed wiring board is housed. Defines the injection amount of the resin. Therefore, there is a problem that the amount of the resin cannot be less than the injection amount.
[0006]
In order to solve the above problem, a resin coating layer for covering a printed wiring board on which electronic components are mounted is formed by insert molding of a thermoplastic resin, and the board is covered with the resin coating layer and sealed. A sealed electronic component unit has been proposed (for example, see Patent Document 2).
[0007]
The insert molding is performed by disposing the printed wiring board in a cavity of a mold and injecting a thermoplastic resin such as a polyamide resin into the cavity. Since the thermoplastic resin such as the polyamide resin can be melted at a relatively low temperature and injected at a relatively low pressure, the electronic components mounted on the printed wiring board may be damaged by heat or pressure during molding. Can be avoided.
[0008]
However, the resin coating layer formed by the insert molding causes heat shrinkage when solidified by cooling, and the stress due to the heat shrinkage may cause a problem such as deformation of the printed wiring board such as warpage. There is.
[0009]
[Patent Document 1]
Japanese Utility Model Publication No. 6-11535 [Patent Document 2]
JP 2000-133665 A
[Problems to be solved by the invention]
An object of the present invention is to provide a resin-sealed electronic component unit that eliminates such inconveniences and includes a resin coating layer formed by insert molding and that can suppress deformation due to the resin coating layer.
[0011]
Another object of the present invention is to provide a method of manufacturing the resin-sealed electronic component unit.
[0012]
[Means for Solving the Problems]
In order to achieve the object, a resin-sealed electronic component unit of the present invention includes a printed wiring board, an electronic component mounted on the board, and sealing the electronic component by covering the electronic component by insert molding. The resin-encapsulated electronic component unit, comprising: a resin coating layer, the resin-encapsulating layer having a temperature lower than a melting temperature of solder used for mounting the electronic component at a temperature of the substrate surface during the insert molding. It is made of resin and is arranged on both front and back surfaces of the substrate, and the amount of the thermoplastic resin forming the resin coating layer is substantially symmetrically arranged on both front and back surfaces of the substrate.
[0013]
The electronic component is generally mounted on the printed wiring board by soldering. Therefore, when the temperature of the thermoplastic resin is higher than the melting temperature of the solder at the time of the insert molding, the solder may be melted.
[0014]
In this regard, in the resin-encapsulated electronic component unit of the present invention, the resin coating layer may be configured such that the temperature on the surface of the printed wiring board during the insert molding is lower than the melting temperature of the solder used for mounting the electronic component. It is made of a plastic resin. Therefore, melting of the solder can be avoided.
[0015]
Further, in the resin-sealed electronic component unit of the present invention, the resin coating layer is disposed on both the front and back surfaces of the printed wiring board, and the amount of the thermoplastic resin forming the resin coating layer is determined on both the front and back surfaces of the substrate. Are arranged substantially symmetrically. Therefore, in the resin coating layer, the amount of the thermoplastic resin is substantially equal on both the front and back surfaces of the printed wiring board. Therefore, the stress at the time of cooling and solidification of the thermoplastic resin is substantially uniform on both the front and back surfaces of the printed wiring board, and the deformation of the board due to the stress can be prevented.
[0016]
Further, in the resin-sealed electronic component unit of the present invention, it is preferable that the resin coating layer has a shape along the outer shape of the electronic component. Since the resin coating layer has a shape along the outer shape of the electronic component, the required amount of the thermoplastic resin forming the resin coating layer can be reduced.
[0017]
The resin-sealed electronic component unit of the present invention is characterized in that the insert molding is performed using a thermoplastic resin whose temperature at the surface of the substrate during the insert molding is lower than a melting temperature of solder used for mounting the electronic component. The substrate is disposed in the cavity of a mold having a cavity in which the amount of the thermoplastic resin forming the resin coating layer disposed on both the front and back surfaces is substantially symmetrically disposed on the front and back surfaces of the substrate. , And by simultaneously injecting the thermoplastic resin into the front and back surfaces of the substrate.
[0018]
According to the manufacturing method of the present invention, by simultaneously injecting the thermoplastic resin on the front and back surfaces of the printed wiring board, the stress when the thermoplastic resin is cooled and solidified is substantially uniform on the front and back surfaces of the substrate. The deformation of the substrate can be suppressed.
[0019]
In the manufacturing method, it is preferable that the insert molding is performed by a mold having a cavity having a shape along an outer shape of the printed wiring board on which the electronic component is mounted. By doing so, it is possible to form the resin coating layer having a shape along the outer shape of the electronic component, and it is possible to reduce the required amount of the thermoplastic resin forming the resin coating layer.
[0020]
Further, by reducing the required amount of the thermoplastic resin, heat is less likely to be trapped inside the mold, and a rise in the mold temperature can be suppressed. It is also possible to reduce the volume of the mold.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a plan view showing one embodiment of a resin-sealed electronic component unit of the present invention, FIG. 2 is a plan view showing an example of a printed wiring board on which electronic components are mounted, and FIG. It is explanatory sectional drawing which shows one Embodiment of the manufacturing method of a component unit.
[0022]
Next, an embodiment of the resin-sealed electronic component unit of the present invention will be described. As shown in FIG. 1, a resin-sealed electronic component unit 1 of the present embodiment includes a resin coating layer 3 made of a polyamide resin on both front and back surfaces of a mounted printed wiring board 2. The mounting printed wiring board 2 has a plurality of electronic components 5 such as semiconductors and LSIs mounted on one surface of a rectangular printed wiring board 4 by soldering.
[0023]
The resin-sealed electronic component unit 1 includes a mounting flange 6 formed integrally with the resin coating layer 3 so as to be connected to both ends on the short side of the printed wiring board 4, and the mounting hole 7 is formed in the flange 6. Is provided. The printed wiring board 4 has cable connecting portions 9a and 9b on the surface to which a plurality of input / output cable groups 8a and 8b are connected, and the cable groups 8a and 8b are on the long side of the printed wiring board 4. One by one is drawn out of the printed wiring board 4 via grommets 10a and 10b which are connected to the ends and integrally formed with the resin coating layer 3.
[0024]
In the resin-sealed electronic component unit 1, the resin coating layer 3 is made of a thermoplastic resin, for example, a polyamide resin, whose temperature on the surface of the mounted printed wiring board 2 during molding is lower than the melting temperature of the solder used for mounting the electronic components 3. Is formed. The resin coating layer 3 is disposed on both the front and back surfaces of the mounting printed wiring board 2, and the amount of the polyamide resin forming the resin coating layer 3 is substantially symmetrically disposed on both the front and back surfaces of the mounting printed wiring board 2. I have.
[0025]
Next, a method for manufacturing the resin-sealed electronic component unit 1 shown in FIG. 1 will be described with reference to FIGS.
[0026]
In the method of manufacturing a resin-sealed electronic component unit according to the present embodiment, the mounted printed wiring board 2 shown in FIG. As described above, the mounted printed wiring board 2 has a plurality of electronic components 5 such as semiconductors and LSIs mounted on one surface of the printed wiring board 4, and enters the cable connection portions 9a and 9b provided on the surface. A plurality of output cable groups 8a and 8b are connected. The mounted printed wiring board 2 does not include the mounting flange 6 and the grommets 10a and 10b.
[0027]
In the method of manufacturing the resin-sealed electronic component unit of the present embodiment, first, as shown in FIG. 3A, the mounting printed wiring board shown in FIG. 2 is placed in the cavities 12a and 12b of the aluminum molds 11a and 11b. 2 is arranged. 3 (a) to 3 (c) schematically show the cavities 12a and 12b and the mounted printed wiring board 2, and do not coincide with the configurations shown in FIGS. 1 and 2. There are parts.
[0028]
The cavity 12a of the mold 11a has a shape along the outer shape of the mounted printed wiring board 2, more specifically, a shape along the outer shape of the electronic component 5 mounted on the printed wiring board 4. On the other hand, the cavity 12b of the mold 11b has a runner 13 that communicates with the cavity 12b and injects the polyamide resin.
[0029]
Further, the cavities 12 a and 12 b have a shape in which the amount of the polyamide resin to be introduced is substantially symmetrically arranged on both the front and back surfaces of the mounting printed wiring board 2. As a result, in the manufacturing method of the present embodiment, the amount of the polyamide resin in the resin coating layer 3 formed by the cavities 12a and 12b is substantially equal on both the front and back surfaces of the mounting printed wiring board 2, and the polyamide resin is cooled. The deformation of the mounted printed wiring board 2 due to the stress at the time of solidification can be suppressed.
[0030]
Here, the “substantially symmetric” may be an amount that can suppress deformation of the mounted printed wiring board 2 due to stress when the polyamide resin introduced into the cavities 12 a and 12 b is cooled and solidified. The amount of the introduced polyamide resin may not be completely symmetrically arranged on the front and back surfaces of the mounted printed wiring board 2.
[0031]
The cavities 12a and 12b of the dies 11a and 11b are provided with a grommet forming portion (not shown) for forming a grommet described later at one end on the long side of the mounted printed wiring board 1.
[0032]
Next, as shown in FIG. 3B, the molds 11a and 11b are closed. At this time, the mounting printed wiring board 1 is held at a position where the printed wiring board 2 faces the runner 13 in the cavities 12a and 12b by a holding pin (not shown).
[0033]
Next, the polyamide resin is introduced into the cavities 12a and 12b by injecting the polyamide resin from the runner 13. The polyamide resin is heated and melted at a temperature of 210 to 220 ° C. in a storage tank (not shown), and is sent to the runner 13 at a pressure of about 1 to 4 MPa by a pressure pump provided in the storage tank. . As a result, when the polyamide resin reaches the surface of the mounted printed wiring board 2 held in the cavities 12a and 12b, the temperature becomes about 160 ° C., and the solder (for example, Pb: Sn) used for mounting the electronic component 5 is used. = 6: 4 (weight ratio)).
[0034]
Further, since the mounted printed wiring board 2 is held at a position facing the runner 13 in the cavities 12a and 12b, the polyamide resin is simultaneously injected onto both the front and back surfaces of the mounted printed wiring board 2.
[0035]
The polyamide resin introduced into the cavities 12a and 12b radiates heat in a short time through the aluminum molds 11a and 11b to be cooled and solidified, thereby forming the resin coating layer 3 covering the mounted printed wiring board 2. . At this time, the mounting flange 6 and the grommets 10a and 10b are formed integrally with the resin coating layer 3. The holding pin is pulled out when the mounting printed wiring board 2 is supported by the introduced polyamide resin, and the trace of the holding pin is filled with the polyamide resin. Therefore, no trace of the pressing pin remains on the resin coating layer 3.
[0036]
Next, when the polyamide resin is cooled and solidified, the molds 11a and 11b are opened as shown in FIG. Take out the component unit 1. In the resin-sealed electronic component unit 1, the resin coating layer 3 has a shape along the outer shape of the electronic component 5 on the side of the mounted printed wiring board 2 on which the electronic component 5 is mounted. On the opposite side of the mounted printed wiring board 2 from the side on which the electronic component 5 is mounted, the resin coating layer 3 is arranged such that the resin amount of each part is substantially symmetric with the side on which the electronic component 5 is mounted. ing. Specifically, by coating the electronic component 5 on the side where the electronic component 5 is mounted, the substantial resin coating layer 3 is formed on the side where the electronic component 5 is not mounted. The coating layer 3 is formed thick. In a portion where the electronic component 5 is not mounted on the side where the electronic component 5 is mounted and the resin coating layer 3 is thinly formed on the surface of the printed wiring board 2, the resin coating layer is formed even on the side where the electronic component 5 is not mounted. 3 is formed thin.
[0037]
As a result, the resin coating layer 3 has substantially the same amount of resin on both the front and back surfaces of the mounted printed wiring board 2, and the stress generated due to cooling and solidification is equalized on both the front and back surfaces of the mounted printed wiring board 2. You. Therefore, in the resin-sealed electronic component unit 1, deformation such as warpage of the mounted printed wiring board 2 due to the stress can be suppressed.
[0038]
In this embodiment, the polyamide resin is used as the thermoplastic resin. However, the temperature of the thermoplastic resin at the surface of the mounted printed wiring board 2 at the time of the insert molding is determined by melting of the solder used for mounting the electronic components 5. Any resin may be used as long as it is lower than the temperature. Examples of such a thermoplastic resin include polyester manufactured by Toyobo Co., Ltd. (trade names: Byron HM grade GM950, Byron HM grade GAA10) and the like.
[Brief description of the drawings]
FIG. 1 is a plan view showing one embodiment of a resin-sealed electronic component unit of the present invention.
FIG. 2 is a plan view showing an example of a printed wiring board on which electronic components are mounted.
FIG. 3 is an explanatory sectional view showing one embodiment of a method for manufacturing a resin-sealed electronic component unit of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Resin-sealed electronic component unit, 3 ... Resin coating layer, 4 ... Printed wiring board, 5 ... Electronic component.

Claims (4)

A resin-sealed electronic component unit including a printed wiring board, an electronic component mounted on the substrate, and a resin coating layer that covers the electronic component by insert molding and seals the electronic component.
The resin coating layer is made of a thermoplastic resin whose temperature at the surface of the substrate during the insert molding is lower than the melting temperature of the solder used for mounting the electronic component, and is disposed on both the front and back surfaces of the substrate. A resin-sealed electronic component unit, wherein an amount of the thermoplastic resin forming a resin coating layer is substantially symmetrically arranged on both front and back surfaces of the substrate. The resin-sealed electronic component unit according to claim 1, wherein the resin coating layer has a shape along the outer shape of the electronic component. A method of manufacturing a resin-sealed electronic component unit including a printed wiring board, an electronic component mounted on the board, and a resin coating layer that covers the electronic component by insert molding and seals the electronic component.
The insert molding uses a thermoplastic resin whose temperature at the surface of the substrate at the time of the insert molding is lower than the melting temperature of solder used for mounting the electronic component, and the resin coating provided on both front and back surfaces of the substrate. Disposing the substrate in the cavity of a mold having a cavity in which the amount of the thermoplastic resin forming a layer is arranged substantially symmetrically on the front and back surfaces of the substrate, and disposing the thermoplastic resin in the cavity. A method for manufacturing a resin-sealed electronic component unit, wherein the method is performed by simultaneously injecting the resin onto both front and back surfaces of a substrate. The method for manufacturing a resin-sealed electronic component unit according to claim 3, wherein the insert molding is performed by a mold having a cavity having a shape along the outer shape of the printed wiring board on which the electronic component is mounted.

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