JPH0144221Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a jet solder bath used for soldering printed circuit boards and electronic components.

[Conventional technology]

Solder, which is melted in a soldering bath for soldering, must be kept at an appropriate soldering temperature.
This is because there is an optimal soldering temperature for solder, which depends on its composition, the size of the object to be soldered, the material, etc., and soldering at this temperature will not cause defects, and the printed circuit board will not cause any damage to electronic components. This is because there is less heat influence.

The temperature of the solder bath containing molten solder is controlled by sensing the temperature with a thermocouple immersed in the molten solder.
The temperature sensed by the thermocouple is sent as an electrical signal to the temperature controller, and the temperature controller determines whether the electrical signal from the thermocouple is higher or lower than the set temperature and turns on the heater in the soldering bath. This is done by turning it off.

However, in conventional jet soldering baths, defects such as icicles and bridging often occur in the soldered parts, no matter how precisely the temperature set by the temperature controller is set to the optimum soldering temperature. In order to investigate the cause of this, the present inventors measured the temperature of the molten solder jetting from the nozzle using another temperature measuring device, and found that the molten solder was at the temperature set by the temperature controller, that is, the optimum solder temperature. It was found that the soldering temperature was lower than the soldering temperature, and that this caused the soldering defects as described above. This is because in conventional jet soldering baths, the tip of the thermocouple that measures the temperature is placed near the heater at the bottom of the soldering bath.
A thermocouple measures the hot solder heated by a heater, and this hot temperature is regarded as the soldering temperature; in reality, the molten solder jetted from the soldering nozzle is lower than that. . Therefore, the inventors of the present invention considered installing a thermocouple near the nozzle that actually performs soldering. When molten solder is not jetted to reduce solder oxidation and save energy, the thermocouple cannot come into contact with the molten solder, and the thermocouple remains cold, so the electrical signal from the thermocouple is transmitted to the temperature controller. The temperature is much lower than the set temperature. Therefore, since the heater in the solder bath remains energized, the temperature of the molten solder in the solder bath becomes considerably higher than the set temperature. When the high-temperature molten solder is jetted out, the molten solder comes into contact with a thermocouple, and the thermocouple senses the temperature of the high-temperature molten solder for the first time, and the temperature controller stops energizing the heater.
Even when the heater is turned off, the molten solder, which has reached a high temperature, does not immediately drop to the set temperature, resulting in the inconvenience that soldering cannot be performed during this time. Further, if soldering work is performed while the molten solder is still at a high temperature, printed circuit boards, electronic components, etc. may be thermally damaged.

[Purpose of invention]

The object of the present invention is to provide a jet soldering bath in which the optimum temperature set by a temperature controller is always the actual soldering temperature.

[Structure of the idea]

This invention installs thermocouples at positions where they can always contact the solder even when there is no jet of molten solder, and at positions where they cannot come into contact with the solder when there is no jet but can come into contact with the molten solder when the jet is flowing. This is a jet soldering bath in which the thermocouple temperature measurement also changes when changing from time to jet state.

The present invention is characterized by installing a thermocouple in a jet solder bath in which molten solder is jetted from a nozzle at a position where it can come into contact with the molten solder that is jetting out during the molten solder jet.
Thermocouples are also installed in positions where they can be in constant contact with the solder, and one thermocouple that comes in contact with the molten solder jet measures the temperature of the molten solder only when the molten solder is flowing, and the other thermocouple measures the temperature of the molten solder only when the molten solder is not jetted. The temperature of the solder is measured only when it is in a jet soldering bath.

〔Example〕

The present invention will be explained below based on the drawings.

A nozzle 2 is installed in a jet solder bath 1, and jet press plates 3, 3 are attached to both sides of the nozzle 2. The lower part of the nozzle is connected to a jet pump (not shown), which is rotated by a pulley 4 placed above the solder S. The pulley 4 is rotated by a motor 5 installed outside the solder bath. A thermocouple 6 is installed approximately in the center of the nozzle through a jet pressure plate 3. The thermocouple 6 is in a position where it cannot come into contact with molten solder when the motor 5 is not rotating, that is, when molten solder is not jetted from the nozzle 2 as shown in FIG. A thermocouple 7 is installed in one corner of the solder tank with its tip inserted deeply into the solder tank. The thermocouple 7 is always in contact with the solder, regardless of whether the molten solder is flowing or not. One thermocouple 6 measures the temperature of the molten solder only when the molten solder is flowing, and the other thermocouple 7 is switched so as to measure the temperature of the solder only when the molten solder is not flowing. This switching can be easily done using an appropriate circuit such as sequencer control or a relay circuit.If the switching is to be done while driving the motor, a timer should be installed in the circuit to check the temperature of the molten solder when it leaves the nozzle. It is also possible to measure the The code 8 is
This is a heater that heats the solder in the solder bath.

[Effect of idea]

In the jet soldering bath of this invention, thermocouples are installed in the actual soldering area and in the area where the solder can be constantly contacted, and the temperature of the solder is measured by switching between the jet and non-jet states, so that the temperature of the solder can be measured. It is possible to eliminate soldering defects caused by the low temperature of the molten solder, and it also has an excellent effect never seen before in that there is no failure to abnormally heat the molten solder even when there is no jet flow.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an embodiment of the present invention, and Fig. 2 is a perspective view of an embodiment of the present invention.
It is a sectional view taken along the line A-A. 1... Jet solder bath, 2... Nozzle, 3... Jet pressure plate, 6, 7... Thermocouple.

Claims (1)

[Scope of utility model registration request] In a jet solder bath where molten solder is jetted from a nozzle, a thermocouple is installed in a position where it can come in contact with the molten solder that is jetting out when the molten solder is jetted, and a thermocouple is also installed in a position where it can always come into contact with the solder. However, one thermocouple in contact with the molten solder jet measures the temperature of the molten solder only when there is a jet of molten solder, and the other thermocouple measures the temperature of the solder only when there is no jet of molten solder. A jet soldering bath.