AMMP-5618-TR2 View Datasheet(PDF) - Agilent Technologies, Inc
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Description
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AMMP-5618-TR2 Datasheet PDF : 9 Pages
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Solder Reflow Profile
The most commonly used solder
reflow method is accomplished in
a belt furnace using convection
heat transfer. The suggested
reflow profile for automated
reflow processes is shown in
Figure 24. This profile is designed
to ensure reliable finished joints.
However, the profile indicated in
Figure 1 will vary among differ-
ent solder pastes from different
manufacturers and is shown here
for reference only.
Stencil Design Guidelines
A properly designed solder
screen or stencil is required to
ensure optimum amount of solder
paste is deposited onto the PCB
pads. The recommended stencil
layout is shown in Figure 25. The
stencil has a solder paste deposi-
tion opening approximately 70%
to 90% of the PCB pad. Reducing
stencil opening can potentially
generate more voids underneath.
On the other hand, stencil
openings larger than 100% will
lead to excessive solder paste
smear or bridging across the I/O
pads. Considering the fact that
solder paste thickness will
directly affect the quality of the
solder joint, a good choice is to
use a laser cut stencil composed
of 0.127 mm (5 mils) thick
stainless steel which is capable of
producing the required fine
stencil outline.
The combined PCB and stencil
layout is shown in Figure 26.
300
Peak = 250 ± 5°C
250
Melting point = 218°C
200
150
100
50
Ramp 1 Preheat Ramp 2 Reflow
0
Cooling
0
50
100
150
200
250
300
Seconds
Figure 24. Suggested Lead-Free Reflow Profile for SnAgCu Solder Paste.
0.60
0.95
0.36
0.70
1.60
0.9550
0.36
1.80
0.27
0.36
0.40
4x - R0.14
Figure 25. Stencil Outline Drawing (mm).
0.60 0.67
3.20 1.80 0.40
0.36
0.40
0.46
0.36
0.40
0.27
0.30
1.60
Stencil
Opening
2.90
Figure 26. Combined PCB and Stencil Layouts (mm).
8
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