HSMS-2805 Datasheet, PDF (6/10 Pages) AVAGO TECHNOLOGIES LIMITED – Surface Mount RF Schottky Barrier Diodes

SMT Assembly
Reliable assembly of surface mount components is a
complex process that involves many material, process, and
equipment factors, including: method of heating (e.g., IR
or vapor phase reflow, wave soldering, etc.) circuit board
material, conductor thickness and pattern, type of solder
alloy, and the thermal conductivity and thermal mass of
components. Components with a low mass, such as the
SOT package, will reach solder reflow temperatures faster
than those with a greater mass.
Avago’s SOT diodes have been qualified to the time-
temperature profile shown in Figure 8. This profile is
representative of an IR reflow type of surface mount as-
sembly process.
After ramping up from room temperature, the circuit
board with components attached to it (held in place
with solder paste) passes through one or more preheat
zones. The preheat zones increase the temperature of the
board and components to prevent thermal shock and
begin evaporating solvents from the solder paste. The
reflow zone briefly elevates the temperature sufficiently
to produce a reflow of the solder.
The rates of change of temperature for the ramp-up and
cool-down zones are chosen to be low enough to not
cause deformation of the board or damage to compo-
nents due to thermal shock. The maximum temperature
in the reflow zone (T_MAX) should not exceed 260°C.
These parameters are typical for a surface mount assem-
bly process for Avago diodes. As a general guideline, the
circuit board and components should be exposed only
to the minimum temperatures and times necessary to
achieve a uniform reflow of solder.
Tp
T_L
Ts _max
Ramp-up
tp
t_L
Critical Zone
T _L to Tp
Ts _min
ts
Preheat
Ramp-down
25
t 25° C to Peak
Time
Figure 8. Surface Mount Assembly Profile.
Lead-Free Reflow Profile Recommendation (IPC/JEDEC J-STD-020C)
Reflow Parameter
Average ramp-up rate (Liquidus Temperature (T_S(max) to Peak)
Preheat
Temperature Min (T_S(min))
Temperature Max (T_S(max))
Time (min to max) (t_S)
Ts(max) to TL Ramp-up Rate
Time maintained above:
Peak Temperature (T_P)
Time within 5 °C of actual Peak temperature (t_P)
Ramp-down Rate
Temperature (T_L)
Time (t_L)
Time 25 °C to Peak Temperature
Note 1: All temperatures refer to topside of the package, measured on the package body surface
6
Lead-Free Assembly
3°C/ second max
150°C
200°C
60-180 seconds
3°C/second max
217°C
60-150 seconds
260 +0/-5°C
20-40 seconds
6°C/second max
8 minutes max