JP2769160B2 - Electronic component mounting method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting an electronic component such as a chip-type component on a printed wiring board with high accuracy.

2. Description of the Related Art In recent years, electronic components, particularly chip components, have been increasingly miniaturized.

Hereinafter, an example of a method for attaching the above-described conventional chip component to a printed circuit board will be described with reference to the drawings.

FIG. 2 is a process diagram showing a conventional method for mounting chip components.

In the figure, first, a portion of a conductor 2 formed on a substrate 1 on which a resist 3 is not formed is formed by electroplating,
The solder 4 is formed by a molten solder immersion method or the like (second
(A), and then apply a flux 5 over the entire surface so as to cover the substrate 1, the resist 3, and the solder 4 (FIG. 2 (b)).
Next, after positioning the electrode 7 of the chip component 6 and the solder 4, they are temporarily fixed at the same time as the mount using the adhesive force of the flux 5 (FIG. 5C), and finally from 200 ° C. to 250 ° C.
Then, the solder 4 was re-melted by passing through a reflow furnace heated to form an electrode 7 and an alloy layer of the chip component 6, and the chip component 6 was attached to the substrate 1 (FIG. 2 (d)).

However, in the above configuration, the flux 5
Since the application amount of the solder cannot be controlled, the solvent component of the flux 5 below the chip component 6 violently boil before the solder 4 is melted, so that the chip component 6 is displaced and the chip component 6 stands up (Manhattan phenomenon). Cases had also occurred.

In view of this problem, the present invention provides an electronic component mounting method that does not cause a displacement of the electronic component.

Means for Solving the Problems In order to achieve this object, an electronic component mounting method according to the present invention comprises a step of forming a solder layer on a portion of a conductor formed on a substrate where a resist is not formed; The method includes a step of applying a flux only on the layer by screen printing, and a step of mounting a chip-type electronic component on a pair of solder layers to which the flux has been applied, and reflowing the solder layer.

Operation With this configuration, since no flux is applied to the lower part of the electronic component, the displacement of the electronic component and the Manhattan phenomenon due to the boiling of the flux do not occur.

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

FIG. 1 is a process chart showing an electronic component mounting method according to one embodiment of the present invention. In FIG. 1, first, a solder layer 14 is formed by electroplating or molten solder immersion on a portion of a conductor 12 formed on a substrate 11 where a resist 13 is not formed (FIG. 1A). Then, a rosin flux 15 is applied on the solder layer 14 by a screen printing method ((b) in the same figure). Next, the electrode 17 of the chip component 16 and the solder layer 14 are aligned, and then the chip component 16 is applied to the substrate 11. It is mounted and temporarily fixed using the adhesive force of the flux 15 ((c) in the same figure). Finally, it is passed through a reflow furnace heated to a temperature of 200 ° C. to 250 ° C. to melt the solder layer 14 and chip components. 16 electrodes
The chip component 16 is mounted on the substrate 11 after forming an alloy layer with the alloy 17 (FIG. 4D).

As described above, according to the embodiment, by partially applying the flux 15 on the solder layer 14, the displacement of the chip component 16 and the Manhattan phenomenon are eliminated.

Effect of the Invention As described above, the present invention can prevent the displacement of the electronic component and the Manhattan phenomenon due to the boiling of the solvent in the flux by applying the flux only to the land where the electronic component is to be mounted.

[Brief description of the drawings]

1 (a) to 1 (d) are process cross-sectional views showing a method of attaching an electronic component according to an embodiment of the present invention, and FIGS. 2 (a) to 2 (d).
FIG. 4 is a process sectional view showing a conventional electronic component mounting method. 11 ... board, 12 ... conductor, 13 ... resist, 14 ... solder layer, 15 ... flux, 16 ... chip parts, 17 ... electrodes.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukio Maeda 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-55-67190 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05K 3/34

Claims (1)

(57) [Claims] A step of forming a solder layer on a portion of the conductor formed on the substrate on which a resist is not formed, a step of applying a flux only on the solder layer by screen printing, Mounting a chip-type electronic component on a pair of applied solder layers, and reflowing the solder layer.