Instructions Instruction Manual

Gull Wing Surface mount Foot Soldering Instructions
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The gull wing style, surface mount foot (parts with a 'SF-'
prefix and a '-G' suffix) is designed to solder to a quad
flat pack (QFP) surface mount land pattern. The emulator
foot emulates the physical characteristics of a QFP gull
wing package very closely, allowing the foot to be
soldered to a target board land pattern using the methods
commonly employed in attaching actual QFP packages.
The recommended method is explained below with visual
aids showing the step-by-step process. This method has
produced very good results. Figure 1 shows the surface
mount emulator foot and a clean target printed circuit
board. The steps involved in the soldering process follow.
CAUTION: During secondary reflow (i.e. mounting the
emulator foot to a board), the temperature profile should
be tightly controlled. The gull wing leads are attached to
the emulator foot with 95/5 tin/silver solder(melting point
245°C). If the temperature during reflow exceeds 245°C,
it will cause bridging between the leads or create opens at
the clip head. The peak temperature during reflow should
not reach more than 240°C. Peaks to 260°C are allowed
only if the residence time is less that 40 seconds above
240°C. If you are attaching the emulator board to a target
board using a hot soldering iron, this can easily happen.
We strongly recommend that furnaces are profiled every
day.
REFLOW OVEN - Soldering method #1
(a) Determine an appropriate temperature solder paste for
your application.
(b) Apply a continuous bead of paste to the target PCB
pads as shown in Figure 2. Cover approximately 1/3 of the
pad between the center of the pad and the outer edge. Begin with this amount and add additional paste after
reflow, if necessary (excessive paste on an initial trial will
be difficult to remove).
(c) Note the target PCB QFP land pattern and the
emulator foot Pin 1 locations.
(d) Align and place the emulator foot onto the solder
paste and land pattern as shown in Figure 3. 'Pick and
place' equipment or a vacuum pen, are recommended (if
they will accommodate the foot), but, handling the foot
by the gold pins and placing on the land pattern by hand
will suffice.
(e) Reflow target PCB with emulator foot in reflow oven
(convection, IR, etc.). The recommended reflow profile is
shown in the Figure 5. Time and temperature settings will
be determined by the manufactures of the solder paste and
Figure 1: Target PCB/Emulator Foot
Figure 2: Apply Solder Paste
Figure 3: Align foot on the lands