center of the solder pad have the role of reform automatically. Also in the
humid of the solder flux the solder tin and surface metal of components formed
alloy layer infiltrated into components structural organization, which form the
ideal soldering structural. Setting the time about (10~30s), a large area and the
larger components shade of PCB should be set much longer time. The small
area or less parts PCB set shorter time generally. In order to ensure quality of
back solder in this stage should shorten the time as much as possible to
protecting components.
4.
The purpose and role of the heat preservation
Let high-temperature liquid solder solidified into solid-state soldering
points. Solidification quality has a direct impact the crystal structure of the
solder and mechanical properties. If the solidification to fast will lead the solder
formation of crystalline rough, solder joint is not bright, mechanical properties
decrease. Under high temperature and mechanical impact, soldering points
easily crack lose mechanical and electrical connections role, lower product
durability. We always use to stop heating methods and heat preservation for
some time. In the temperature slow decline process the solder can solidification
and crystal good. Generally set the temperature point lower than the solder
point 10-20 ° C around. Use of natural cooling when the temperature dropped
to the temperature point it will enter cooling paragraph.
5.
The purpose and role of the cooling paragraph
This cooling segment is simple, usually cooled to the temperature will not
scalding the people. To speed up the process of operation, may also stop the
process when the temperature fell to below 150
. To avoid burns to use tools,
hand belt or heat resistant grove take out the PCB board.
6. Note
General temperature curve set from the low-temperature, after satisfy the
soldering requirements as much as possible to reduce the soldering
temperature. Also can through extend back soldering time to reduce the
temperature, this will be conducive to the protection of low-temperature
components, especially some connectors and plug. Some components can not
satisfy temperature requirement, can be used to after soldering to solve.
