HSDL-3211 Datasheet, PDF (9/18 Pages) AVAGO TECHNOLOGIES LIMITED – IrDA® Data Compliant Low Power 1.15 Mbit/s Infrared Transceiver

Recommended Reflow Profile
255
230
220
200
180
R2
160
120
R1
80
25
MAX. 260°C
R3
R4
60 sec.
MAX.
ABOVE
220°C
R5
0
50
100
150
200
250
300
P1
HEAT
UP
t-TIME (SECONDS)
P2
SOLDER PASTE DRY
P3
SOLDER
REFLOW
P4
COOL DOWN
Process Zone
Heat Up
Solder Paste Dry
Solder Reflow
Cool Down
Symbol
P1, R1
P2, R2
P3, R3
P3, R4
P4, R5
∆T
25°C to 160°C
160°C to 200°C
200°C to 255°C (260°C at 10 seconds max)
255°C to 200°C
200°C to 25°C
Maximum ∆T/∆time
4°C/s
0.5°C/s
4°C/s
-6°C/s
-6°C/s
The reflow profile is a straight-
line representation of a nominal
temperature profile for a convec-
tive reflow solder process. The
temperature profile is divided
into four process zones, each with
different ∆T/∆time temperature
change rates. The ∆T/∆time rates
are detailed in the above table.
The temperatures are measured
at the component to printed
circuit board connections.
In process zone P1, the PC board
and HSDL-3211 castellation pins
are heated to a temperature of
160°C to activate the flux in the
solder paste. The temperature
ramp up rate, R1, is limited to
4°C per second to allow for even
heating of both the PC board and
HSDL-3211 castellations.
Process zone P2 should be of
sufficient time duration (60 to
120 seconds) to dry the solder
paste. The temperature is raised
to a level just below the liquidus
point of the solder, usually 200° C
(392° F).
Process zone P3 is the solder
reflow zone. In zone P3, the
temperature is quickly raised
above the liquidus point of solder
to 255° C (491° F) for optimum
results. The dwell time above the
liquidus point of solder should be
between 20 and 60 seconds. It
usually takes about 20 seconds to
assure proper coalescing of the
solder balls into liquid solder and
the formation of good solder
connections. Beyond a dwell time
of 60 seconds, the intermetallic
growth within the solder connec-
tions becomes excessive, result-
ing in the formation of weak and
unreliable connections. The
temperature is then rapidly
reduced to a point below the
solidus temperature of the
solder, usually 200° C (392° F), to
allow the solder within the
connections to freeze solid.
Process zone P4 is the cool down
after solder freeze. The cool down
rate, R5, from the liquidus point
of the solder to 25° C (77° F)
should not exceed 6° C per second
maximum. This limitation is
necessary to allow the PC board
and HSDL-3211 castellations to
change dimensions evenly,
putting minimal stresses on the
HSDL-3211 transceiver.
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