JPS61287197A - Manufacture of electronic component - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing an electronic component in which chip components are mounted on both sides of a wiring board.

[Technical Background of the Invention and Problems Therewith] Generally, in ceramic multilayer wiring boards and the like, the back side of the board is often used to increase the integration density. Conventionally, as a method for mounting chip components such as ICs on both sides of a board, as shown in Fig. 2(a),
As shown in the figure, the solder paste 3 is printed and dried on the conductor pattern on the main surface A of the wiring board 4 to form the solder-printed pad 2, and after mounting the component 1 such as 1C thereon, the solder paste 3 is printed and dried on the conductor pattern on the main surface A of the wiring board 4, and after mounting the component 1 such as 1C thereon, After gluing and fixing the components, the wiring board 4 is then turned over and solder paste 3 is printed and dried on the conductor pattern at the back opening to form a solder-printed batt 2, on which components 11 such as ICs are attached. The method used was to mount the parts and use belt reflow to adhere and fix the parts.

However, in this conventional method, as shown in FIG. 2(b), when belt reflow is performed on the back side opening, the heat is transferred to the main surface A, and as a result, parts are attached to the main surface A of the board 4. There has been a problem in that the solder that adheres parts 1 to each other melts, causing parts 1 to fall off or even shift. In this case, even if an attempt is made to bond the missing component 1 on the main surface A again by belt reflow, the solder on the back opening facing downward will melt, and a similar problem will occur for the component 11.

As described above, in the conventional method, inconveniences such as missing parts that are difficult to correct already occur during component mounting. As a result, parts may be missing, or even if they are only misaligned, they are easy to come off, resulting in a product that lacks reliability and does not have a good appearance.

Therefore, as shown in Figure 3, Sn/Pb-63/37, which has a melting point of 183°C and is a common solder paste, is used for the back opening.
Use a low melting point solder paste 3' such as
), e.g. Sn/P with a melting point of 280°C.
If a high melting point solder paste 3'' such as b = 10/90 is used, the solder on the main surface A that has been hardened earlier by the belt reflow at the back opening will not melt (this can prevent parts from falling off, etc.).

However, with this method, the high melting point solder paste 3'' used on the main surface A has poor wettability and cannot be wetted neatly onto the pad.
The surface of the main surface A is as shown in FIG. 4, and the appearance is extremely poor and cannot be used as a product.

Furthermore, as shown in FIG. 5, when mounting the component 1 on the main surface A of the board 24, if the component 1 is bonded with non-conductive epoxy resin 8 or the like on the outside of the pad, the component 11 can be mounted on the back opening. Even if the solder on the main surface A melts during reflow bonding, the component 1 will not shift.

However, this method requires a step of applying non-conductive epoxy resin to a limited number of small areas, which increases the cost of the product. In addition, as shown in Part 1 in Figure 5, too much non-conductive epoxy resin may be applied, causing the part to float off the pad, or non-conductive epoxy resin may flow onto the conductor pad, causing electrical problems between the component and the conductor pattern. There are problems such as interfering with the connection.

[Purpose of the Invention] The present invention has been made to solve these problems, and when mounting chip components such as ICs on both sides of a wiring board, there is no damage to the appearance and there is no contact between the components and the conductor pattern. It is an object of the present invention to provide a method for manufacturing electronic components that has good electrical connection and is free from inconvenience in the mounting process.

[Summary of the Invention] That is, the method for manufacturing an electronic component of the present invention includes a first step of printing and drying a solder paste at a predetermined position on a conductor pattern arranged on a wiring board, and a pad on which this solder paste is printed. The second step is to mount the chip components on the wiring board, the third step is to bond and fix the chip components onto the wiring board by belt reflow, and to apply sealing resin to the peripheral area of the fixed chip components. a fourth step of injecting and curing to protect and seal the chip component; a fifth step of printing and drying a solder paste at a predetermined position on a conductive pattern placed on the back surface of the chip component; The present invention is characterized by comprising a sixth step of mounting the chip component on a pad printed with solder paste, and a seventh step of adhering and fixing the chip component onto the wiring board by belt reflow.

[Embodiments of the invention] Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1(a), the component 1 is mounted on the solder-printed pad 2 placed at a predetermined position on the main surface A of the wiring board 34, and the pad 2 is placed on the solder-printed pad 2 by belt reflow.
Part 1 was glued and fixed to.

Next, as shown in FIG. 1(b), a molten sealing resin 9 was injected into the periphery of the component 1 including the joint, and then hardened to protect and seal the component 1. As this sealing resin, for example, silicone resin or epoxy resin can be used. Next, the board 34 is turned over, and the solder paste 3 is printed and dried on the conductor pattern of the back opening as shown in FIG. By doing so, the component 11 was bonded and fixed. During the belt reflow of the component 11, the component 1 on the main surface A was protected and sealed with the sealing resin, so it did not come off or shift, and the resulting product was highly reliable.

[Effects of the Invention] As explained above, according to the present invention, when chip components are mounted on both sides of a wiring board, the components do not come off or shift, so component mounting processes such as mounting and belt reflow can be easily performed. This improves the yield and reliability of the product. Furthermore, the surface of the component sealed with a resin such as Epoquin resin has the advantage that the component can be protected from scratches and dirt, and is also excellent in durability.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically explaining the steps of an embodiment of the present invention, FIG. 2 is a diagram schematically explaining the steps of a conventional electronic component manufacturing method, and FIG. 3 is a diagram schematically explaining the steps of a conventional electronic component manufacturing method. 4 is a plan view thereof, and FIG. 5 is a diagram schematically illustrating another conventional example. 1.11...Parts

Claims (1)

[Claims] (1) A first step of printing and drying a solder paste at a predetermined position on a conductor pattern placed on a wiring board, and a second step of mounting a chip component on the pad printed with this solder paste, A third step is to adhere and fix the chip component onto the wiring board by belt reflow, and to protect and seal the chip component by injecting a sealing resin into the peripheral area of the fixed chip component and curing it. a fourth step, and a fifth step of printing and drying the solder paste at a predetermined position on the conductor pattern placed on the back surface of the chip component.
, a sixth step of mounting the chip component on the pad printed with this solder paste, and a seventh step of bonding and fixing the chip component onto the wiring board by belt reflow. Characteristic manufacturing method for electronic components.