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Bottom Termination Soldering Techniques
The Ironwood Electronics, Bottom Termination adapters are designed to solder to the
standard gull-wing type quad flat pack
(QFP) surface
mount land pattern. Because Ironwood
Bottom Terminations adapters do not
emulate the physical characteristics of a QFP
gull-wing package, the methods used to
solder it to a target PCB are different. The
recommended method is explained below
with visual aids showing the step-by-step
process. This method has produced very
good results.
Figure 1: Target PCB/Emulator Foot
surface mount emulator foot and a clean target printed circuit board. The bottom side of
the surface mount foot is
covered by 0.005" thick kapton tape to
provide insulation and clearance from the
target PCB as recommended by IPC-A610B, Section 10.2.1 chip
components/bottom only termination
standard.
The steps involved in the soldering
process are as follows:
(1) Using a flux dispenser, place a small
amount of Tac flux (water soluble or no
clean) on the four corner pads of the
target PCB as shown in Figure 2.
Figure 3: Align the Foot to PCB
Figure 1 shows a Bottom Termination
Figure 2: Placing Tac Flux
(2) Note the target board QFP land pattern and
the adapter Pin 1 locations. Place
the adapter onto the flux and land pattern as
shown in Figure 3. Handle the adapter by
grasping the PCB edge (handle by pins when
available) and aligning it on the land pattern
with the aid of a microscope.
(3) Holding the adapter in place, by pressing
down gently, use the soldering iron and tack
the four corner pads with the aid of a
microscope. This will keep the foot in
alignment.
Tel: (800) 404-0204
www.ironwoodelectronics.com
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Tel: (800) 404-0204
www.ironwoodelectronics.com
Bottom Termination Soldering Techniques (cont.)
(4) Apply a generous amount of flux along the side of the adapter PCB as shown in
Figure 4.
(5) Using a very fine tipped soldering iron (spade tip 0.03" diameter and 60° chisel
angle), add solder to the soldering tip using solder wire (low temp, 63Sn/37Pb) to form a
blob of solder approximately 1/8" diameter on its tip. Use a microscope or magnifying
lens, if available, to view the process while
soldering.
(6) Start at one corner and pull the tip of the
soldering iron along the side of the foot as
shown in Figure 5. Continue down the side of
the foot until a suitable fillet is present
between
all adapter pads and target PCB pads.
(7) Repeat this step for the remaining three
Figure 4: Applying Flux
emulator foot. Excessive heat or pressure
may damage the pads on the adapter or on
the target PCB.
(8) Clean thoroughly in an ultra-sonic
cleaner. The picture of the solder
connection is shown
in Figure 6.
The adapter is similar to discrete chip
components, leadless chip carriers, and
other devices that have metalized
terminations on the bottom side only. The
Figure 6: Solder Connections
sides of the adapter. Caution must be used
when touching the soldering iron tip to the
Figure 5: Soldering Process
solder joints produced by the above process
are acceptable under class 1 and 2 of IPC-A610B, Section 10. 2. 1, Chip
Components/Bottom only Terminations
standard.
filename: KSI.doc, Rev A
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