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MMSF5N02HDR2 View Datasheet(PDF) - Motorola => Freescale

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MMSF5N02HDR2 Datasheet PDF : 10 Pages
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MMSF5N02HD
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/in-
frared 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
STEP 1
PREHEAT
ZONE 1
“RAMP”
STEP 2
VENT
“SOAK”
STEP 3
HEATING
ZONES 2 & 5
“RAMP”
STEP 4
STEP 5
HEATING HEATING
ZONES 3 & 6 ZONES 4 & 7
“SOAK”
“SPIKE”
DESIRED CURVE FOR HIGH
MASS ASSEMBLIES
160°C
170°C
STEP 6
VENT
STEP 7
COOLING
205° TO 219°C
PEAK AT
SOLDER JOINT
150°C
100°C
150°C
100°C
140°C
SOLDER IS LIQUID FOR
40 TO 80 SECONDS
(DEPENDING ON
MASS OF ASSEMBLY)
DESIRED CURVE FOR LOW
MASS ASSEMBLIES
50°C
TIME (3 TO 7 MINUTES TOTAL)
TMAX
Figure 16. Typical Solder Heating Profile
Motorola TMOS Power MOSFET Transistor Device Data
9
 

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