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MUN5315DW1T1 参数 Datasheet PDF下载

MUN5315DW1T1图片预览
型号: MUN5315DW1T1
PDF下载: 下载PDF文件 查看货源
内容描述: 双偏置电阻晶体管 [Dual Bias Resistor Transistors]
分类和应用: 晶体小信号双极晶体管光电二极管
文件页数/大小: 16 页 / 310 K
品牌: MOTOROLA [ MOTOROLA ]
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SOLDER STENCIL GUIDELINES  
Prior to placing surface mount components onto a printed  
or stainless steel with a typical thickness of 0.008 inches.  
The stencil opening size for the surface mounted package  
should be the same as the pad size on the printed circuit  
board, i.e., a 1:1 registration.  
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  
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 25 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 177189°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.  
STEP 5  
HEATING  
ZONES 4 & 7  
“SPIKE”  
STEP 6 STEP 7  
VENT COOLING  
STEP 1  
PREHEAT  
ZONE 1  
“RAMP”  
STEP 2  
VENT  
“SOAK” ZONES 2 & 5  
“RAMP”  
STEP 3  
HEATING  
STEP 4  
HEATING  
ZONES 3 & 6  
“SOAK”  
205  
PEAK AT  
SOLDER JOINT  
° TO 219°C  
200  
°
C
C
170°C  
DESIRED CURVE FOR HIGH  
MASS ASSEMBLIES  
160°C  
150°C  
150°  
SOLDER IS LIQUID FOR  
40 TO 80 SECONDS  
(DEPENDING ON  
140°C  
100°C  
MASS OF ASSEMBLY)  
100  
°
C
C
DESIRED CURVE FOR LOW  
MASS ASSEMBLIES  
50°  
TIME (3 TO 7 MINUTES TOTAL)  
T
MAX  
Figure 46. Typical Solder Heating Profile  
14  
Motorola Small–Signal Transistors, FETs and Diodes Device Data