K0900E70 Datasheet, PDF (151/224 Pages) Teccor Electronics – Thyristor Product Catalog

Application Notes
Wave Soldering
Wave soldering is the most commonly used method for soldering
components in PCB assemblies. As with other soldering pro-
cesses, a flux is applied before soldering. After the flux is
applied, the surface mount devices are glued into place on a PC
board. The board is then placed in contact with a molten wave of
solder at a temperature between 240 °C and 260 °C, which
affixes the component to the board.
Dual wave solder baths are also in use. This procedure is the
same as mentioned above except a second wave of solder
removes excess solder.
Although wave soldering is the most popular method of PCB
assembly, drawbacks exist. The negative features include solder
bridging and shadows (pads and leads not completely wetted) as
board density increases. Also, this method has the sharpest ther-
mal gradient. To prevent thermal shock, some sort of pre-heating
device must be used. Figure AN1005.6 shows the procedure for
wave soldering PCBs with surface mount devices only. Figure
AN1005.7 shows the procedure for wave soldering PCBs with
both surface mount and leaded components.
or
Apply glue
Screen print glue
AN1005
PC board
Insert
leaded
components
Turn over the
PC board
Apply
glue
Place
SMDs
Cure
glue
Turn over the
PC board
Wave solder
Place component
Cure glue
Wave solder
Figure AN1005.6 Wave Soldering PCBs With Surface Mount Devices
Only
Figure AN1005.7 Wave Soldering PCBs With Both Surface Mount
and Leaded Components
Immersion Soldering
Maximum allowed temperature of the soldering bath is 235 °C.
Maximum duration of soldering cycle is five seconds, and forced
cooling must be applied.
Hand Soldering
It is possible to solder the DO-214, Compak, and TO-252 devices
with a miniature hand-held soldering iron, but this method has
particular drawbacks and should be restricted to laboratory use
and/or incidental repairs on production circuits.
Recommended Metal-alloy
(1) 63/37 Sn/Pb
(2) 60/40 Sn/Pb
Pre-Heating
Pre-heating is recommended for good soldering and to avoid
damage to the DO-214, Compak, TO-252 devices, other compo-
nents, and the substrate. Maximum pre-heating temperature is
165 °C while the maximum pre-heating duration may be 10 sec-
onds. However, atmospheric pre-heating is permissible for sev-
eral minutes provided temperature does not exceed 125 °C.
©2002 Teccor Electronics
Thyristor Product Catalog
AN1005 - 3
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