JPS6276541A - Soldering - Google Patents

Abstract

PURPOSE:To reduce a dangerousness and a necessary time by quickly lowering a part until the portion to be soldered of the part is brought into contact with the surface of molten solder, once stopping the lowering of the part when said portion is brought into contact with the surface, keeping stationary for a predetermined time and then again lowering the part at a low speed to allow the portion to be soldered of the part to be completely dipped in the molten solder. CONSTITUTION:A part (p) is quickly lowered from a position above a molten solder (s) until the tips of the leads l of the part (p) are brought into contact with the surface of the molten solder (s) by the length of degree of 0.1-3mm and stopped to be lowered when in contact, being then kept stationary for 1-10sec. The part (p) is lowered again at a low speed and the leads l are dipped in the molten solder to the roots of the leads l. The leads l are kept to be dipped in the solder (s) for a predetermined time to build up a thermal balance between the solder and the leads l and the solder (s) is sufficiently attached to the leads l. Then, the part (p) is lifted at a low speed from a dipping state to a position where the tips of the leads l leave the surface of the molten solder (s) and thereafter, changing a lifting speed from last-said position, at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for soldering leads, etc. of components of semiconductor devices and the like.

[Prior art]

Conventionally, when using soldering equipment to solder the leads of components such as semiconductor devices, the components are dipped all at once into molten solder in a solder bath at a constant speed, and after a certain period of time, the components are pulled up at a constant speed. I went all at once.

FIG. 2 shows a diagram of the process. In this figure 2, S indicates the molten solder in the tank, the arrow t indicates the elapsed process time, and the circled numbers indicate the height position of the component (more precisely, the part to be soldered) at each process time. It shows. This circle number indicates the position relative to the molten solder.
They correspond to the circled numbers in the diagram. p is a component (in this example, a semiconductor device), and β is a lead thereof. This lead 1 is the part to be soldered.

As is clear from FIG. 2, conventional soldering consists of three steps. That is, (1), the process from ■ to ■ (2), the process from ■ to ■ (3), and the process from ■ to ■.

The process from ■ to ■ in (1), that is, the process in which the component p to be soldered is transferred from a position above the molten solder S to inside the molten solder S is represented by a downward straight line, and the component p is lowered at a constant speed 7, and the lead β portion is immersed in the molten solder S all at once to the area where soldering is required.

In (2), the horizontal portion (■-■) indicates that the lead 2 portion of the component p is immersed in the molten solder S and remains stationary for a certain period of time.

The transition from ■ to ■ in (3) is represented by an upward straight line, indicating that component p is pulled up from within the molten solder S to a position above it at a constant speed and returned to its original position. .

In this way, the conventional method involves the step of immersing the component P into the molten solder S all at once and then pulling it out from there all at once, which causes solder scattering, shaking of the solder surface, frequent occurrence of flux fumes, etc. Further, when pulling up the G, there were problems such as bridging between the leads and generation of icicles.

[Purpose of the invention]

It is an object of the present invention to provide a soldering method that eliminates the above-mentioned problems by stabilizing molten solder in a stationary state as much as possible and by making it possible to preheat parts.

[Structure of the invention]

To this end, the soldering method of the present invention involves rapidly lowering the part to be soldered until the tip of the part contacts the surface of the molten solder, and at the point of contact, stopping the lowering once and allowing it to stand still for a certain period of time. The part to be soldered is then lowered again at a low speed so that the part to be soldered is completely immersed in the molten solder, and after maintaining the immersion for a certain period of time, the part to be soldered is lowered until the tip of the part to be soldered is on the surface of the molten solder. I try to pull it up at a low speed until it leaves.

〔Example〕

Hereinafter, embodiments of the soldering method of the present invention will be described.

FIG. 3 is an explanatory diagram showing the process in a diagram.
Consists of 6 steps. That is, (1), the process from ■ to ■ (2), the static process of ■ (3), the process from ■ to ■ through ■ (4), the static process of ■ (5), the process from ■ to ■ Step (6) is a step from ■ to ■.

As is clear from the nearly vertical straight line, the process (1) moves the component p to a position above the molten solder S (
The tip of the lead L is brought into contact with the surface of the molten solder S by 0.1 to 31 degrees (state of ■). Once you make contact, stop your descent.

In step (2), this stopped state is maintained for 1 to 10 seconds. From now on, the lead 1 is preheated by the heat of the molten solder S to reduce the temperature difference between it and the solder.

In the next step (3), the component p is lowered again at a low speed, and the lead β is immersed in the molten solder S up to its root.
1 (state of ■).

In step (4), this immersion state is maintained for a certain period of time to create a thermal equilibrium state between the solder and the lead, and the lead P
Apply molten solder S to the surface.

Then, in step (5), the component p is pulled up from this immersed state at a low speed to a position where the tip of the lead l does not come into contact with the surface of the molten solder S (state of ■).

In the final step (6), the pulling speed after the state (2) is changed to be rapid. Note that there is no problem in performing the pulling at a low speed following the pulling in step (5) without changing the speed of this pulling. Finally, the part p is returned to its initial position (the shape B).

As a result, since the parts to be soldered are preheated before the parts are soldered, the activation of the flux is improved, and flux fumes are not generated all at once when the parts to be soldered are immersed in molten solder. It can be prevented. Furthermore, scattering or shaking of the molten solder is suppressed to the utmost, so the danger is reduced.

Furthermore, since the pulling is performed slowly, it is possible to prevent the formation of solder bridges and icicle-like solder on the soldered portion, thereby reducing the occurrence of unevenness in the soldering finish.

〔Effect of the invention〕

From the above, according to the present invention, solder scattering, which has been a problem in the past, can be avoided.
It can effectively prevent shaking of the solder surface, frequent occurrence of Franks fumes, solder bridges and icicles, and the vertical movement of parts in the first and last processes can be performed at a high speed, so the overall The time required for the process can be shortened.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing each process of soldering a semiconductor device, Fig. 2 is an explanatory diagram showing the steps of a conventional soldering method in a diagram, and Fig. 3 is an explanatory diagram showing the steps of a conventional soldering method. It is an explanatory view showing a process in a diagram. S...molten solder, p...parts (semiconductor device),!・
...The part to be soldered (lead) of the component.

Claims (1)

[Claims] (1). In a method of soldering by dipping the part of the part to be soldered into molten solder for a certain period of time and then pulling it up, the part is rapidly lowered until the tip of the part to be soldered contacts the surface of the molten solder. At the point of contact, the descent is stopped once and kept at rest for a certain period of time, and then the part is lowered again at a low speed to completely immerse the part to be soldered into the molten solder, and after continuing the immersion for a certain period of time, the part A soldering method in which the tip of the part to be soldered is pulled up at a low speed until it separates from the surface of the molten solder.