JPH0548258A - Soldering method for electronic component - Google Patents

Abstract

PURPOSE:To provide a method for soldering an electronic component, in which melted solder is brought into contact only with a part necessary to be soldered of the component, a part not to be brought into contact with the solder is protected against adherence of solder, and further a solder ball, solder tailings are not adhered. CONSTITUTION:A method for soldering an electronic component comprises the steps of exposing melted solder 2 from a slitlike opening 3, bringing only a part necessary to be soldered of the component such as an electrode 7 into contact with the slit 3 to be in contact with the solder 2, and inhibiting to bring a part not to be brought into contact with the solder 2 such as a resistor 6, into contact with the solder 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering method for various electronic parts, and more particularly to a soldering method in which a portion other than a necessary portion does not come into contact with the solder.

[0002]

2. Description of the Related Art Conventionally, as a method of soldering electronic parts, there are immersion soldering, flow soldering and reflow soldering.

Of these, the immersion soldering and the flow soldering are for soldering the entire electronic component by bringing it into contact with the molten solder. In the reflow soldering, solder is applied in advance to the portion requiring soldering. Then, the solder is soldered by melting the solder by heating thereafter.

[0004]

In the immersion soldering and the flow soldering, since the entire component comes into contact with the molten solder, there is an element which has a weak element to heat and dislikes the contact with the molten solder. Cannot be used for parts.

Further, although solder balls, solder dust, etc. adhere to the entire parts due to contact with molten solder, when cleaning the flux of electronic parts after soldering, no cleaning is performed as a measure against freon / trichloroethane regulation. There is a method, and as a condition for performing the non-cleaning method, there is a condition that the residual amount of the flux does not cause a problem in the electrical and mechanical reliability of the electronic component and that the solder ball and the solder residue are not attached. The solder balls and solder debris adhered by the above-mentioned conventional soldering method must be removed by ultrasonic cleaning with a solvent and the like, which is troublesome.

Also, in reflow soldering, cream solder is usually used, but the viscosity of the cream solder may decrease during preheating, causing so-called sagging, and the solder may spread to areas other than the required portion. It cannot be used in the case of electronic parts in which the place where the contact between the attachment part and the solder is disliked is close.

Therefore, in the present invention, a soldering method is provided in which the solder is contacted only with a necessary portion, the portion which is unfavorable to the contact with the solder is protected from the adhesion of the solder, and further the solder ball and the solder residue are not adhered. To do.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention exposes molten solder through a slit-shaped opening, and uses only the portion of the electronic component that requires soldering as molten solder. This is a soldering method in which other parts are brought into contact with each other so as not to come into contact with molten solder.

[0009]

Since the soldering portion of the electronic component is applied to the slit-shaped opening and the molten solder protruding from the opening is brought into contact with the solder, soldering is performed, so that the slit-shaped opening is not abutted. The molten solder does not contact the part of.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 to 3, reference numeral 1 denotes a solder bath made of stainless steel, and a molten solder 2 is filled therein.

A slit-shaped opening 3 is provided on the upper surface of the solder bath 1. In this opening 3, since the stainless steel in the cross section of the opening repels the molten solder, the solder surface does not rise to the upper surface of the stainless steel plate but protrudes in a semicircular cross section due to surface tension.

The width of the slit of the opening 3 is set so as to be equal to the width of the portion for soldering the electronic component.

A liquid level adjusting portion 4 having an open upper surface is provided at an end of the solder bath 1. The height H of the solder liquid level of the liquid level adjusting portion 4 is set to be higher than the height of the opening 3. By increasing the height H and adjusting the height H, the height of the molten solder surface protruding from the opening 3 can be adjusted.

The resistors to be soldered are the substrate 5,
It is composed of a resistor 6, a thick film silver electrode 7 and a lead terminal 8. The resistor 6 and the thick film silver electrode 7 are printed and fired on the substrate 5, and the lead terminal 8 is inserted and fitted to fit the electrode portion 7. And the lead terminal 8 are brought into contact with each other, and then flux is applied.

Next, the resistors are aligned so that the electrode portions 7 thereof overlap the slit portions 3 of the solder bath 1, and
It is placed on the slit part 3 as shown in FIG.

Here, the lead terminal 8 comes into contact with the molten solder 2 protruding from the slit portion 3, and the wetting of the lead terminal 8 to the molten solder 2 starts. As solder wetting progresses,
The molten solder 2 is sucked up by the electrode portion 7, and the entire electrode portion 7 is covered with the molten solder 2.

At this time, since the projection 10 provided near the slit portion 3 on the upper surface of the solder bath 1 contacts the substrate 3, the resistor 6 does not contact the solder bath 1 and is protected from heat. Further, since the resistor 6 has no wettability to the solder, the wet-up of the molten solder 2 is completed at the electrode portion 7, and the resistor 6 does not contact the molten solder 2.

After the completion of the wetting, the resistor is pulled up, as shown in FIG.
Like the solder fillet 9, the electrode part 7 and the lead terminal 8
The soldering is completed by covering only the above and not adhering to other parts such as the resistor 6.

Therefore, even when the heat-sensitive resistor 6 and the electrode portion 7 are close to each other, the resistor 6 can be soldered without coming into contact with the molten solder 2.

The present invention is not limited to the resistor, but can be effectively implemented as long as it is a component in which the electrode portion and the portion that does not want to contact the solder are present in close proximity.

[0022]

As described above, according to the soldering method of the present invention, even when the electrode portion to be soldered and the portion which is reluctant to contact the solder are extremely close to each other, the portions other than the electrode portion are in contact with the solder. Can be completely prevented.

Further, since solder balls and solder debris do not adhere to the entire parts, it is possible to save the time and effort of removing the solder balls and the like by ultrasonic cleaning using a solvent in advance when performing flux cleaning.

Further, since only the necessary portion comes into contact with the solder, it is not necessary to apply the solder paste and the solder resist to the electronic parts in advance, and there is an effect of reducing the cost by reducing the number of steps.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the method of the present invention before soldering.

FIG. 2 is a vertical sectional view showing soldering of the method of the present invention.

FIG. 3 is a vertical sectional view showing the method of the present invention after soldering.

[Explanation of symbols]

 2 Molten solder 3 Slit-shaped opening 6 Resistor 7 Electrode

Claims (1)

[Claims] 1. The molten solder is exposed from the slit-shaped opening so that only a portion of the electronic component that needs to be soldered is brought into contact with the molten solder and other portions are prevented from coming into contact with the molten solder. Soldering method for electronic components.