HSDL-3208-021 查看數據表（PDF） - HP => Agilent Technologies

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HSDL-3208-021

Ultra Small Profile Package IrDA® Data Compliant Low Power 115.2 kbit/s Infrared Transceiver

HP => Agilent Technologies 

Reflow Profile

230

200

183

170

150

R2

125

100

R1

MAX. 245°C

R3

R4

90 sec.

MAX.

ABOVE

183°C

R5

50

25

0

50

100

150

200

250

300

P1

HEAT

UP

t-TIME (SECONDS)

P2

SOLDER PASTE DRY

P3

SOLDER

REFLOW

P4

COOL

DOWN

Figure 13. Reflow graph.

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 125°C

125°C to 170°C

170°C to 230°C (245°C at 10 seconds max.)

230°C to 170°C

170°C to 25°C

Maximum ∆T/∆time

4°C/s

0.5°C/s

4°C/s

–4°C/s

–3°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 ∆T/∆time tempera-

ture 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 transceiver’s castella-

tion I/O pins are heated to a

temperature of 125°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 transceiver’s

castellation I/O pins.

Process zone P2 should be of

sufficient time duration (>60

seconds) to dry the solder paste.

The temperature is raised to a

level just below the liquidus point

of the solder, usually 170°C

(338°F).

Process zone P3 is the solder

reflow zone. In zone P3, the

temperature is quickly raised

above the liquidus point of solder

to 230°C (446°F) for optimum

results. The dwell time above the

liquidus point of solder should be

between 15 and 90 seconds. It

usually takes about 15 seconds to

assure proper coalescing of the

solder balls into liquid solder and

the formation of good solder

connections. Beyond a dwell time

of 90 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 170°C (338°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

-3°C per second maximum. This

limitation is necessary to allow

the PC board and transceiver’s

castellation I/O pins to change

dimensions evenly, putting

minimal stresses on the

transceiver.

9

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