测温板制作方法与实验

REFLOW测温板制作方法与实验

Measuring Temp.Profiles

Measuring of Temperature Profiles in a Reflow System爐爐說

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils General論

Temperature profiles are taken by measuring systems which run through the reflow oven. Temperature sensors are located on different positions on the PCB, and the temperatures during the run are stored in the internal memory. After passing the oven the system is connected to a PC, the data is then transfered and displayed on the screen.

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils Temperature SensorsMost of the measuring systems on the market are working with thermocouples. The thermocouple type is very often K which stands for NiCr - Ni and is indicated by the green isolation material of the wire and the yellow connector. For quick and accurate temperature response, the thermocouple should be less in mass and diameter.

do 0,1 mm

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils Thermocouple MountingFixing the thermocouple wire with Capton tape to the board

Before fixing the thermocouple tip, make sure that the two nonisolated wires do not touch each other !兩不19.09.2000/Leon Hsu Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils Thermocouple Mounting Defects

If the thermocouple tip is twisted, the temperature is measured at the closest short of the wires to the connector. In the picture left, the temperature is measured at this location and not at the tip !!度,度, !

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils Thermocouple Mounting with epoxy glue

Fixing the thermocouple tip with epoxy glue to the selected component

Disadvantage is the fact, that the glue has to be cured before the board can be used for measuring. Sometimes glue spread to much, or to much glue will affect the temperature.量不,度

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils Thermocouple Mounting with high temp. Solder

Fixing the thermocouple tip with high temp solder to the selected component.

This is a quick and safe method to fix the sensors, as long as not to much solder is used.量不

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils Thermocouple Mounting Defects不良

Four thermocouples were mounted in different ways to a QFP. This test setup was heated with an hot air blower which was set to a constant temperature. The heat up of the component was very even and homogeneous.

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils Thermocouple Mounting Defects

T

= 24,5°C !

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils Thermocouple Mounting Defects

!

度

!度

T

= 24,5°C !

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

REFLOW测温板制作方法与实验

Measuring Temp. Profils Thermocouple Mounting– Result不良說

This experiment shows that it is substancial to mount thermocouples always in the same way and with the same amount of epoxy or high temp solder ! Twist

ed thermocouple tips must be avoided as they measure the temperature somewhere but not at the tip ! When reflow systems are evaluated or tested T is very often the criteria to compare the different systems. In this case the thermal profiling has to be done very accurate and percise, otherways the T form the measurement is biger than the T from the oven.

19.09.2000/Leon Hsu

Reflowseminar_1.ppt

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