Capillay: When melt solder wets to the component pin but still stays far away from the contact area, Pseudo soldering will be caused. The reason is that when solder is melting, pin temperature is higher than pad temperature. Improvement measures: Use more bottom heating (reflow oven with upper and lower heating modes are used) or very low temperature rise rate (between preheating and melting point) to realize an equilibrium with soldering pad before pins are wetted by solder.

Three . Reflow profile test

If you want to test the E-THERM reflow profile, temperature collector (i.e., temperature memory device) which can go into the oven chamber along with the PCBs is generally used. This collector is equipped with K-type thermocouples (which are made from different materials depending on the range of temperatures to be measured and measuring accuracy). Preferred thermocouple diameters are 0.1~0.3 mm.

After testing, data in memory device are transferred to a PC-dedicated test software to analyze and process and then component profiles are printed out.

1. Installation of thermocouple

(a) When installing and using thermocouple to sense temperature, you must make sure that no short circuit occurs except the test point.

Otherwise, you are unable to guarantee the test accuracy. Test points should be as small as possible.

(b) When thermocouple is connected to memory device or other test equipment, its polarity shall be consistent with the equipment requirements.

Thermocouple changes temperature to electromotive force, so polarities should be identified when connecting the thermocouple.

(Our currently used thermocouple's plugs have both positive and negative pins)

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