Soldering is one of the methods of attaching metals to each other with the help of another metal that melts at a lower temperature and, when solidified, creates a strong adhesion of the parts to each other.
Soldering after hardening provides a strong, permanent electrical and mechanical connection. If the soldering does not perform the function of electrical conductivity, then it was done with some kind of violation. The most common defect is cold soldering.
Cold soldering is a defect in which the soldered joints do not form strong electrical and mechanical contact. Such a poor-quality connection occurs if a number of rules for the production of soldering work are not observed.
The approximate procedure for the production of soldering works is as follows. Previously, before soldering, it is necessary to thoroughly moisten the output of the part and the platform where it will be installed with flux. Next, warm up the soldering iron and cut off about 1 mm of solder from the tin wire with its sting. Wait a little for the solder to reach the required temperature. Then, with a soldering iron tip, the tin is applied to the contact pad and the output of the part. The sting should touch the site with its entire front edge, and not one of its corners.
When the solder hits the contact pad, it will spread itself over the surface, you should not specially press on the soldering point or drive it with a soldering iron. If, nevertheless, the tin does not lay down evenly over the entire area, then you should run the tip of the soldering iron along the part that is not covered with solder. This must be done quickly, but not in jerks, but smoothly. Continue to heat the leg of the part and the working area with the tip of the soldering iron for a few more seconds until an even and shiny connection is obtained.
High-quality soldering is considered when there is not a lot of solder on the contact pad, but enough. Tin must lie in an even layer over the entire surface of the site; there must be no gaps or holes between the leg of the part and the place where it is soldered.
The main reasons for the occurrence of cold soldering: insufficient temperature of the soldering equipment (180 ° C-220 ° C), at these temperatures the tin does not melt, but only slightly softens and melts. Perhaps the problem is in the use of a flux of inadequate quality (fluxes destroy oxides on parts and solder, displace air from the soldering zone) or poorly cleaned places intended for soldering, the soldered parts are displaced relative to each other due to weak heating with a soldering iron. Cold soldering can be distinguished from quality soldering by the grain structure of the seam and the dull gray color.