JPS59222994A - Method of mounting electronic part - 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] This invention provides a flat path cage IC on a double-sided printed wiring board.
, relates to a mounting method for re-opening soldering of electronic components such as chip components.

[Prior art]

2. Description of the Related Art Conventional methods for mounting electronic components of this type include those shown in FIGS. 1 to 3. In Figures 1 and 2, l
2 is a double-sided printed wiring board, 2 is a flat package IC 14 temporarily fixed to the surface of this double-sided printed wiring board 1 with an adhesive 3 and then soldered at the refill opening, is a chip component, 5 is a discrete component, and 6 is a double-sided printed wiring board. A chip component 8 is solder which is temporarily fixed to the back surface of the printed wiring board 1 with an adhesive 3 and flow soldered.

Further, in FIG. 3, numeral 7 indicates a chip component soldered to the rift opening without adhesive.

Conventionally, when soldering a flat package IC 2 to a double-sided printed wiring board 1, the first
There are two types: a combined ref-port and flow method as shown in FIG. 2, and a double-sided ref-port method as shown in FIG. In the method shown in FIGS. 1 and 2, the solder 8 of the flat package IC 2 on the front side that has been previously soldered at the rift opening is remelted by the flow soldering heat on the back side, and the adhesive 3 is applied to prevent the IC 2 from shifting its position. I tried to fix it with.

In addition, the method shown in Figure 3 has a flat package IC on the back side.
2, and in this case also the surface flange I
- The flat package IC 2 on the back side to which the rift opening was previously soldered due to the rift opening soldering heat of I C7 and chip component 4.
In order to prevent the solder 8 from shifting or falling off due to re-melting, the adhesive 3 is used to fix the solder 8.

Conventional flat package IC mounting methods use adhesive for temporary fixing as described above, so variations in the amount and position of the adhesive applied can cause the adhesive to adhere to the pattern, resulting in poor soldering. There were problems in terms of connection reliability, such as the lead terminals of the flat package IG being lifted up due to excessive amount of coating, resulting in poor continuity.

[Summary of the invention]

This invention was made to eliminate the drawbacks of the conventional products as described above, and eliminates the need for adhesives by using solder materials with different melting points for soldering on the front and back surfaces. The purpose of the present invention is to provide a method for mounting electronic components that can be used to mount electronic components.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows an electronic component mounting method according to an embodiment of the present invention. When the mounting method of this embodiment is applied to a combination of beam and flow soldering, high-temperature solder 9 with a melting point higher than that of surface dip or flow soldering (usually around 183°C)
Accordingly, the flat package IC 2 is reflow soldered onto the surface of the double-sided printed circuit board 1.

That is, the flat package IC 2 on the surface, the chip component 4
are reflow soldered in advance using solder cream 9 with a high melting point of 221"C, which is a high-temperature solder. Next, dip or flow soldering of the discrete components 5 and chip components 6 on the back side is performed using solder cream 9 with a melting point lower than that on the front surface. (for example, a normal melting point of 183° C.). In this way, since the high-temperature solder 9 on the front surface has a high melting point, the solder on the back surface sometimes does not melt, and therefore the flat package IC 2 or the chip component 4 Since it does not cause misalignment,
Adhesive for temporary fixation on the surface side is not required.

The mounting method of this embodiment as described above eliminates the need for adhesive for temporary fixing, thereby eliminating the problems of poor soldering and poor conductivity caused by variations in the amount and position of adhesive applied. This does not occur and connection reliability can be improved. Additionally, material costs and assembly processing costs can be reduced.

Further, FIG. 5 shows another embodiment of the method of the present invention.

This method is for reflow soldering on both the front and back sides, and uses low temperature solder 10 lower than the melting point of the reflow solder cream 8 of the flat package IC 2 on the back side to reflow solder the flat IC 7 and chip components 4 on the front side. This is what we do.

That is, when mounting a non-heat resistant flat IC 7 by double-sided reflow soldering, first perform reflow soldering of the flat-nod package IC 2 on the back side, and then apply low-temperature solder 10 with a lower melting point (for example, melting point 162) on the front surface. ℃) to reflow solder the flat IC 7 and chip components 4. In this way, the solder 8 on the back side has a higher melting point than the solder 10 on the front side, so it will not melt, and the flat package IC 2 will not be misaligned, peeled off, or fall off. is not necessary.

In addition, in the above example, solder cream (solder paste)
Although the case of Nyororiflow soldering has been described, other conductive bonding materials such as conductive adhesive may be used instead of solder cream, and the same effects as in the above embodiments can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, since solder with different melting points is used on the front and back surfaces, it is possible to eliminate the need for adhesive for temporary fixing, and as a result, the solder connection reliability of electronic components is improved. Also, it has the effect of reducing material costs and assembly processing costs.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the mounting method for conventional reflow/flow soldering, Fig. 2 is a cross-sectional side view of Fig. 1, and Fig. 3 is a cross-sectional side view showing the mounting method for conventional double-sided reflow soldering. FIG. 4 is a cross-sectional side view showing an electronic component mounting method according to one embodiment of the present invention, and FIG. 5 is a cross-sectional side view showing an electronic component mounting method according to another embodiment of the present invention. Agent Masuo Oiwa Figure 1 Figure 3 Figure 4 Figure f1 Co. 5 Procedural amendment (1 shot) 1□8 O. 5.121 Flood 8 Mr. Commissioner of the Japan Patent Office 1. Indication of the case Patent application No. 58-98932 2.
Name of the invention Electronic component mounting method 3, Representative Hitoshi Katayama of the person making the amendment, Department 4, Agent 5, Detailed explanation of the invention column 6 of the specification to be amended, Contents of the amendment fl) Description page 4 In the third line, ``on the front side'' is corrected to ``on the back side''. that's all

Claims (1)

[Claims] (11 Connect electronic components to either the front or back side of the double-sided printed W wiring board using a conductive bonding material with a high melting point,
An electronic component mounting method characterized by connecting an electronic component to the other side using a conductive bonding material having a low melting point.