PCB Arts GmbH
Instruction Manual Vapor Phase One
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5.1.4
Solder paste does not melt
Check your soldering profile again and check the temperature values achieved in the log,
which is automatically saved on the SD card after each soldering process. In case of very high
thermal masses, it may happen that the melting point of the soldering material was not
reached based on the soldering profile. Adjust your soldering profile accordingly.
Check the solder paste and its melting point, if this melting point is higher than the
maximum temperature of the solder profile, the solder paste will not be liquid.
5.2
Solder paste selection
The melting point of the solder paste used must be below the boiling temperature of the
process medium used. When selecting the solder pastes, mildest activated pastes or
NoClean can be used due to the ideal soldering conditions (0 ppm oxygen). In general, all
commercially available pastes can be used.
5.3
Double sided boards
The processing of double-sided PCBs is identical to that of classic soldering methods. Your
board must be placed on the solder grid with spacers - never place a double-sided board
directly on the solder grid.
The heavy components, which have an unfavorable ground-solder surface ratio, should be
fixed with SMD glue. If the heavy components were already taken into account during layout
creation and these were placed on the top side of the board, gluing may not be necessary.
If your assembly allows it, you can also assemble and solder one side of the assembly first.
Afterwards you assemble the other side and do another soldering process.
5.4
Cleaning of printed circuit boards
By using mildly activated or no-clean pastes, cleaning of the assemblies can be dispensed
with in most cases. However, in the case of vapor phase soldered assemblies, the flux
residues can be easily removed using the common cleaning methods, since the flux residues
are not burned onto the board. In general, the surfaces of vapor phase brazed products are
only extremely slightly contaminated. In contrast to convection systems, in which volatile
flux and solvent components are distributed on the surface with the air flow, the soldering
material in vapor phase soldering is located within a high-purity distillation column. This
means that there is no additional contamination of the solder during the heating process.
