MMFT1N10E 查看數據表（PDF） - Motorola => Freescale

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MMFT1N10E

Medium Power Field Effect Transistor

Motorola => Freescale 

MMFT1N10E

SOLDER STENCIL GUIDELINES

Prior to placing surface mount components onto a printed

circuit board, solder paste must be applied to the pads. A

solder stencil is required to screen the optimum amount of

solder paste onto the footprint. The stencil is made of brass or

stainless steel with a typical thickness of 0.008 inches. The

stencil opening size for the SOT–223 package should be the

same as the pad size on the printed circuit board, i.e., a 1:1

registration.

SOLDERING PRECAUTIONS

The melting temperature of solder is higher than the rated

temperature of the device. When the entire device is heated

to a high temperature, failure to complete soldering within a

short time could result in device failure. Therefore, the

following items should always be observed in order to

minimize the thermal stress to which the devices are

subjected.

• Always preheat the device.

• The delta temperature between the preheat and soldering

should be 100°C or less.*

• When preheating and soldering, the temperature of the

leads and the case must not exceed the maximum

temperature ratings as shown on the data sheet. When

using infrared heating with the reflow soldering method,

the difference shall be a maximum of 10°C.

• The soldering temperature and time shall not exceed

260°C for more than 10 seconds.

• When shifting from preheating to soldering, the maximum

temperature gradient shall be 5°C or less.

• After soldering has been completed, the device should be

allowed to cool naturally for at least three minutes.

Gradual cooling should be used as the use of forced

cooling will increase the temperature gradient and result

in latent failure due to mechanical stress.

• Mechanical stress or shock should not be applied during

cooling

* Soldering a device without preheating can cause excessive

thermal shock and stress which can result in damage to the

device.

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

18 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

150°C

100°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

150°C

160°C

170°C

STEP 6 STEP 7

VENT COOLING

205° TO

219°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

50°C

TIME (3 TO 7 MINUTES TOTAL)

TMAX

Figure 18. Typical Solder Heating Profile

8

Motorola TMOS Power MOSFET Transistor Device Data

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