MMDF2P03HDR2 Datasheet, PDF (9/10 Pages) ON Semiconductor – Power MOSFET 2 Amps, 30 Volts P−Channel SO−8, Dual

MMDF2P03HD
TYPICAL SOLDER HEATING PROFILE
For any given circuit board, there will be a group of
control settings that will give the desired heat pattern. The
operator must set temperatures for several heating zones
and a figure for belt speed. Taken together, these control
settings make up a heating “profile” for that particular
circuit board. On machines controlled by a computer, the
computer remembers these profiles from one operating
session to the next. Figure 16 shows a typical heating
profile for use when soldering a surface mount device to a
printed circuit board. This profile will vary among
soldering systems, but it is a good starting point. Factors
that can affect the profile include the type of soldering
system in use, density and types of components on the
board, type of solder used, and the type of board or
substrate material being used. This profile shows
temperature versus time. The line on the graph shows the
actual temperature that might be experienced on the surface
of a test board at or near a central solder joint. The two
profiles are based on a high density and a low density
board. The Vitronics SMD310 convection/infrared reflow
soldering system was used to generate this profile. The type
of solder used was 62/36/2 Tin Lead Silver with a melting
point between 177−189°C. When this type of furnace is
used for solder reflow work, the circuit boards and solder
joints tend to heat first. The components on the board are
then heated by conduction. The circuit board, because it has
a large surface area, absorbs the thermal energy more
efficiently, then distributes this energy to the components.
Because of this effect, the main body of a component may
be up to 30 degrees cooler than the adjacent solder joints.
200°C
150°C
100°C
5°C
STEP 1
PREHEAT
ZONE 1
“RAMP”
STEP 2
VENT
“SOAK”
STEP 3
HEATING
ZONES 2 & 5
“RAMP”
STEP 4
HEATING
ZONES 3 & 6
“SOAK”
DESIRED CURVE FOR HIGH
MASS ASSEMBLIES
150°C
160°C
STEP 5 STEP 6 STEP 7
HEATING VENT COOLING
ZONES 4 & 7
“SPIKE”
205° TO 219°C
170°C
PEAK AT
SOLDER
JOINT
100°C
140°C
SOLDER IS LIQUID FOR
40 TO 80 SECONDS
(DEPENDING ON
MASS OF ASSEMBLY)
DESIRED CURVE FOR LOW
MASS ASSEMBLIES
TIME (3 TO 7 MINUTES TOTAL)
Figure 16. Typical Solder Heating Profile
T_MAX
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