KR19990020370A - Cold soldering soldering device and method - Google Patents

Abstract

The present invention discloses an apparatus and a method for preventing cold solder phenomenon generated when soldering a component mounted on a printed circuit board. The immersion type soldering apparatus according to the present invention penetrates a component inserted into a component insertion hole of a predetermined PCB to increase the number of crystal nuclei generated when soldering the component, and eliminates cold soldering by spreading capillary force. . Increasing the number of crystallization nuclei and the capillary force diffusion of the melt is performed by applying vibrations of predetermined dynamic energy to the PCB from the outside by using an ultrasonic oscillator when soldering the component. Accordingly, the present invention has the advantage of improving the reliability of the soldering process.

Description

Cold soldering soldering device and method

The present invention relates to an apparatus for soldering a component mounted on a printed circuit board, and more particularly, to an apparatus and method for preventing cold solder phenomenon generated during soldering.

Generally, a device for soldering a component mounted on a printed circuit board (PCB) is classified into a soldering apparatus of a surface mounting component (SDM) type and a soldering apparatus of a dipping type. Of these, the immersion type soldering apparatus is implemented in DIP type, WAVE type, and CASCADE type according to the implementation method.

In the immersion type soldering apparatus, a component to be soldered on a PCB is soldered as a molten solder flows into a minute hole of less than 1 mm on the PCB. At this time, mechanical force is activated when molten lead penetrates into the fine hole, which is due to the wetting force by the interaction of capillary action and surface tension. Molten lead spreads evenly across the part legs.

Meanwhile, when soldering using the immersion type soldering apparatus, cold soldering often occurs. Of course, if cold solder occurs, the component in which it occurs is detached from the PCB. In addition, when cold soldering occurs under mass production conditions, the entire PCB in which cold soldering occurs becomes a defective and causes a serious problem of becoming useless. Such cold soldering results in an increase in the time required for the soldering process, thereby lowering production efficiency and reliability.

It is therefore an object of the present invention to provide an apparatus and method for removing cold solder that may occur when soldering with a dip type soldering apparatus.

It is another object of the present invention to provide an apparatus and method for preventing a component from being separated when soldering a component on a PCB by a dip type soldering apparatus.

Still another object of the present invention is to provide an apparatus and method for solving the problem that the entire PCB becomes defective due to poor soldering when soldering a component on the PCB with a dip type soldering apparatus.

It is still another object of the present invention to provide an apparatus and method for improving the reliability of a process of soldering a component on a PCB with a dip type soldering apparatus.

In order to achieve the above objects, the present invention penetrates a melt into a component inserted into a component insertion hole of a predetermined PCB in a immersion soldering apparatus to increase the number of nuclei generated in the melt and spread the capillary force. We propose a method for eliminating cold soldering. Increasing the number of crystallization nuclei and the capillary force diffusion of the melt is performed by applying vibrations of predetermined dynamic energy to the PCB from the outside by using an ultrasonic oscillator when soldering the component.

An anti-cold solder immersion type soldering apparatus according to the present invention includes a PCB having a component insert hole for soldering, a melt contained in a predetermined lead bath and penetrating into the component insert hole of the PCB as the lead bath is heated, and a component insert hole of the PCB. When the melt penetrates into the energy source made of a predetermined dynamic energy to the PCB. As the energy source, an ultrasonic oscillator is used, and when the melt penetrates into the component insertion hole of the PCB, both ends of the PCB are fixed by a predetermined guide holder, and the ultrasonic oscillator contacts the holder to convert vibration into dynamic energy. Will be added.

1 shows a typical soldering process.

Figure 2 is a view showing the configuration of a soldering preventing device for cold soldering according to the present invention.

3 is a view showing the configuration of the ultrasonic oscillator shown in FIG.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of the user or chip designer, and the definitions should be made based on the contents throughout the present specification.

First, prior to explaining the operation according to the present invention look at the main causes of the cold solder phenomenon occurring in the immersion type soldering apparatus.

(1) the defect of the soldering part; Oxide adhesion, oil, foreign substance

(2) lack of required temperature; It inhibits the flow of molten lead, making it difficult for the molten lead to penetrate through the holes.

(3) required temperature overheating; Oxidation of molten lead is accelerated, so that physical properties and fluidity are drastically reduced, making it difficult to attach to the part legs, and even if attached, the resistivity is increased to increase the circuit loss, resulting in poor soldering equivalent to cold solder.

(4) quench after soldering; Appropriate rapid cooling after soldering helps to densify the crystal structure and helps various physical properties, but quenching before penetrating sufficiently causes cold soldering.

(5) solvent (FLUX) problems; Solvents are used to decompose junction oxides and other foreign substances. If a small amount of solvent remains in the soldering portion and does not float on the surface of the molten lead, the flow of molten lead is inhibited and causes cold solder.

For the main causes of the cold soldering phenomenon as described above, the production plant takes various measures such as cleaning the parts and the PCB soldering portion with a solvent before soldering to prevent the occurrence of cold soldering. However, the inventors of the present application have found that cold soldering occurs frequently in mass production conditions even when the above conditions are satisfied. The inventors of the present application also found that cold soldering is associated with a decrease in capillary force and a decrease in the number of nuclei generated.

1 is a view showing a general soldering process to which the present invention is applied.

Referring to FIG. 1, a conventional soldering process includes inserting a part into a hole on a PCB, transferring a PCB into which the part is inserted into a clean room through a conveyor, and heating a molten solder bath in the clean room. The molten lead is penetrated into the hole on the transferred PCB so that a predetermined part is fixed to the corresponding hole.

2 is a view showing the configuration of an anti-cold soldering apparatus according to the present invention, which relates to a process of injecting MELTING SOLDER into a hole on a PCB during the soldering process. The present invention is to close the cold lead phenomenon by increasing the flowability of molten lead and accelerated solvent and reaction speed, increase the speed of the residual solvent, increase the number of nuclei generated when cooling the molten lead to build a fine crystal structure, diffusion of capillary force of molten lead, etc. It is to eliminate the problem completely.

Referring to FIG. 2, the apparatus for preventing cold soldering according to the present invention has a dynamic energy for the activation of solder when the molten lead penetrates into the hole on the PCB to increase the number of crystallization and spread the capillary force. It is characterized by the addition. At this time, the external dynamic energy is a vibration applied by the ultrasonic oscillator.

3 is a view showing the configuration of the ultrasonic oscillator shown in FIG. 2, the ultrasonic oscillator comprises a control signal amplification and rectification circuit 110, an amplitude control amplifier 120, and a vibrating body 130. The control signal amplifying and rectifying circuit 110 includes an amplifier 111, an amplitude setting unit 112, a detector 113, and a time constant determiner 114. The amplitude control amplifier 120 includes a phase determiner 121, a limiter 122, a resonant circuit 123, an amplifier 124, and a power amplifier 125. The vibrating body includes a detector 131, a vibrator 132, and a horn 133. The ultrasonic oscillator having the above configuration is a technique well known to those skilled in the art, and a detailed description thereof will be omitted.

The operation according to the invention is carried out in the process of injecting molten lead into the holes on the PCB during the soldering process as described above. Referring back to FIG. 2, when the PCB 2 is transferred to the clean room through the conveyor, both ends of the PCB 2 are fixed by the PCB guide holders 4 and 6 to be positioned above the molten solder bath 8. At this time, the molten lead contained in the molten solder tank 8 is heated by an inert gas or CO ₂ gas. Therefore, the heated molten lead is introduced into the hole in which the component of PCB 2 is inserted. In this state, the horn 133 of the ultrasonic oscillator 10 having the configuration as shown in FIG. 3 is in contact with the guide holders 4 and 6. Therefore, when molten lead is inserted into the hole into which the PCB 2 component is inserted, vibration generated by the ultrasonic oscillator 10 affects the molten lead inlet of the PCB 2. More specifically, when the melt is injected into the component insertion hole of the PCB inserted by the guide holders 4 and 6, the melt is introduced into the insertion hole corresponding to the short time due to the vibration generated by the ultrasonic oscillator 10. These vibrations increase the number of nuclei generated in the melt, cause diffusion of capillary forces, and consequently act as a cause of eliminating cold solder.

As described above, the present invention eliminates cold soldering by applying vibration, which is dynamic energy, from the outside when the melt penetrates into the component insertion hole of the PCB. Accordingly, there is an advantage of improving the reliability of the soldering process.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

Claims (6)

In the cold soldering immersion type soldering apparatus, A printed circuit board having component inserts for soldering, A melt contained in a predetermined tank and penetrated into a component insertion hole of the printed circuit board as the solder bath is heated; Soldering apparatus comprising an energy source for applying a predetermined mechanical energy to the printed circuit board when the melt penetrates into the component insertion hole of the printed circuit board. The soldering apparatus of claim 1, wherein the energy source is an ultrasonic oscillator. The method of claim 1, wherein when the melt penetrates into the component insertion hole of the printed circuit board, both ends of the printed circuit board are fixed by a predetermined guide holder, and the ultrasonic oscillator contacts the holder to vibrate A soldering apparatus characterized in that applied as a mechanical energy. In the method of removing the cold solder phenomenon in the dip type soldering apparatus, A method of injecting a component inserted into a component insertion hole of a predetermined printed circuit board by penetrating the melt to increase the number of crystal nucleation of the melt and to spread the capillary force. The method according to claim 4, wherein the number of crystal nucleations of the melt is increased and the capillary force is diffused by generating vibration by applying a predetermined mechanical energy to the printed circuit board from the outside during soldering of the component. The method of claim 5, wherein the dynamic energy is vibration generated by an ultrasonic oscillator contacting both ends of the printed circuit board.