Recommended Reflow Profile
MAX. 260°C
R3
R4
255
230
220
200
180
160
120
80
25
0
P1
HEAT
UP
50
100
P2
SOLDER PASTE DRY
150
R1
T – TEMPERATURE – (°C)
R2
60 sec.
MAX.
ABOVE
220°C
R5
200
P3
SOLDER
REFLOW
250
P4
COOL
DOWN
300
t-TIME (SECONDS)
Process Zone
Heat Up
Solder Paste Dry
Solder Reflow
Cool Down
Symbol
P1, R1
P2, R2
P3, R3
P3, R4
P4, R5
DT
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
DT/DTime
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
convective reflow solder process.
The temperature profile is divided
into four process zones, each with
different
DT/Dtime
temperature
change rates. The
DT/Dtime
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 APDS-9002 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
APDS-9002 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
connections becomes excessive,
resulting 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 APDS-9002 castellations to
change dimensions evenly,
putting minimal stresses on the
APDS-9002.
9
HP [ AGILENT(HEWLETT-PACKARD) ]
