Recommended Reflow Profile
255
T - TEMPERATURE (°C)
230
217
200
180
150
120
80
25
0
P1
HEAT
UP
50
100
P2
SOLDER PASTE DRY
150
200
P3
SOLDER
REFLOW
250
P4
COOL DOWN
300
t-TIME
(SECONDS)
MAX 260°C
R3
R2
R1
R4
60 sec to 90 sec
Above 217°C
R5
Process Zone
Heat Up
Solder Paste Dry
Solder Reflow
Cool Down
Peak Temperature
Symbol
P1, R1
P2, R2
P3, R3
P3, R4
P4, R5
∆T
25°C to 150°C
150°C to 200°C
200°C to 260°C
260°C to 200°C
200°C to 25°C
> 217°C
260°C
>255°C
25°C to 260°C
Maximum ∆T/∆time or
Duration
3°C/s
100s to 180s
3°C/s
-6°C/s
-6°C/s
60s to 120s
-
20s to 40s
8mins
Time maintained above liquidus point , 217°C
Time within 5°C of actual Peak Temperature
Time 25°C to Peak Temperature
The reflow profile is a straight-line representation of a
nominal temperature profile for a convective reflow sol-
der process. The temperature profile is divided into four
process zones, each with different
∆T/∆time
temperature
change rates or duration. The
∆T/∆time
rates or duration
are detailed in the above table. The temperatures are
measured at the component to printed circuit board con-
nections.
Process zone P1
, the PC board and component pins are
heated to a temperature of 150°C to activate the flux in
the solder paste. The temperature ramp up rate, R1, is lim-
ited to 3°C per second to allow for even heating of both
the PC board and component pins.
solder to 260°C (500°F) for optimum results. The dwell time
above the liquidus point of solder should be between 60
and 120 seconds. This is to assure proper coalescing of the
solder paste into liquid solder and the formation of good
solder connections. Beyond the recommended dwell time
the intermetallic growth within the solder connections
becomes excessive, resulting in the formation of weak
and unreliable connections. The temperature is then rap-
idly reduced to a point below the solidus temperature of
the solder to allow the solder within the connections to
freeze solid.
Process zone P4
is the cool down after solder freeze. The
Process zone P2
should be of sufficient time duration (100
to 180 seconds) to dry the solder paste. The temperature
is raised to a level just below the liquidus point of the sol-
der.
cool down rate, R5, from the liquidus point of the solder
to 25°C (77°F) should not exceed 6°C per second maxi-
mum. This limitation is necessary to allow the PC board
and component pins to change dimensions evenly, put-
ting minimal stresses on the component.
It is recommended to perform reflow soldering no more
than twice.
Process zone P3
is the solder reflow zone. In zone P3, the
temperature is quickly raised above the liquidus point of
9
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