HSDL-3602 datasheet(13/27 Pages) LITEON

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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 ∆T/∆time tem-

perature change rates. The ∆T/∆time rates are detailed

in the following table. The temperatures are measured

at the component to printed circuit board connections.

In process zone P1, the PC board and HSDL-3602 cas-

tellation 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-3602

castellations.

Process zone P2 should be of sufficient time duration

(60 to 120 seconds) to dry the solder paste. The tem-

perature 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

Maximum

Process Zone

Symbol

∆T

∆T/∆time

Heat Up

P1, R1

25˚C to 160˚C

4˚C/s

Solder Paste Dry

P2, R2

160˚C to 200˚C

0.5˚C/s

Solder Reflow

P3, R3

200˚C to 255˚C

4˚C/s

(260˚C at 10 seconds max.)

P3, R4

255˚C to 200˚C

–6˚C/s

Cool Down

P4, R5

200˚C to 25˚C

–6˚C/s

Recommended Reflow Profile

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 be-

comes 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 maxi-

mum. This limitation is necessary to allow the PC board

and HSDL-3602 castellations to change dimensions

evenly, putting minimal stresses on the HSDL-3602

transceiver.

t-TIME (SECONDS)

230

200

160

120

150

100

200

250

300

180

220

255

HEAT

SOLDER PASTE DRY

SOLDER

REFLOW

COOL

DOWN

60 sec.

MAX.

ABOVE

220 C

MAX. 260 C

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