MMDF4207 Datasheet, PDF (10/11 Pages) ON Semiconductor – Dual P-Channel Field Effect Transistors

MMDF4207
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
STEP 1
PREHEAT
ZONE 1
“RAMP"
STEP 2
VENT
“SOAK"
STEP 3
HEATING
ZONES 2 & 5
“RAMP"
DESIRED CURVE FOR HIGH
MASS ASSEMBLIES
STEP 4
STEP 5
HEATING ^HEATING
ZONES 3 & 6 ^{ZONES 4 & 7}
“SOAK"
“SPIKE"
170°C
160°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)
T_MAX
Figure 16. Typical Solder Heating Profile
DEVICE MARKING
D4207
Device
MMDF4207R2
ORDERING INFORMATION
Reel Size
Tape Width
13″
12 mm embossed tape
Quantity
2500 units
http://onsemi.com
10