For station-type soldering irons which have become mainstream products in recent years, it is recommended that the control is performed based on the leak voltage, the tip-to-ground resistance, and the tip temperature.
The reason for this is that even if the insulation resistance is measured; it will not show the safety at the device side directly because the inside is insulated with a transformer.
To prevent device damage and soldering failure, periodically perform the following inspections (daily or weekly).
In addition to the following inspections 1 through 3, inspections which seem to be required during work should be performed and recorded periodically.
If the tip, element cover, etc. are oxidized, heat conduction will be deteriorated, causing the tip temperature to become lower, resulting in soldering failure. To prevent soldering failure, measure the tip temperature daily.
The indicated tip temperature may be lower than the actual temperature due to other factors. To measure the temperature correctly, see as follows.
The following factors cause electric current to be leaked from the tip to the P.W.B. and the device, resulting in adverse effects on objects being soldered. For this reason, check the leak voltage periodically.
Even though an insulative ceramic material is used, long-term use has caused the heating element to deteriorate and the leak voltage to increase.
Accumulation of oxides on the parts such as tip/element cover caused contact failure to be generated and leak voltage to increase.
The lower the leak voltage, the better.
The MIL standard which has been abolished at present specifies that the leak voltage is designated to be lower than 2mV; therefore, all HAKKO station-type soldering irons have been delivered with the leak voltage set to 2mV or less in conformance to the MIL standard.
Measure leak voltage after adjusting the temperature setting to the maximum.
When the leak voltage is measured at the highest temperature, the highest leak voltage will be recorded. If normal results are obtained even in unfavorable conditions such as at the highest temperature, it is judged that normal results will be obtained at other temperature settings. (This method is based on the MIL standard.)
Oxide and flux stuck on the tip, element cover and nut will cause the tip-to-ground resistance to become higher. As a result, the leak voltage will become higher; therefore, periodically check the tip-to-ground resistance.
As with leak voltage, the lower the tip-to-ground resistance, the better.
The MIL standard which has been abolished at present specifies that the resistance is designated to be lower than 5Ω; therefore, all HAKKO station-type soldering irons have been delivered with the resistance set to 2Ω or less which is stricter than that of the MIL standard.
Polish the contact sections such as the tip and element cover with sandpaper, steel wool, etc. to remove any oxide films.
An oxidized tip causes the wetting characteristics to deteriorate. The FS-100 is convenient to use for recovering the tip wetting characteristics.