2. Selection of test points

Generally, at least three test points are needed which can represent temperature changes on components (reflecting the temperature changes of high-, medium- and low-temperature areas on components). In general, area with the highest temperature lies in the middle of edges without c omponents perpendicular to the direction of transmitting the PCBs; area with the lowest temperature lies at the soldered terminals of large components (PLCC, QFP, etc.) near the center of the PCBs. In addition, test points should be set on the surface of components with poor heat resistance or based on clients' specific requirements.

3. Installation of test points

Thermocouple should be connected with the testing areas reliably. Otherwise, thermal resistance may be caused. Also, materials contacting or fixing the thermocouple should be as less as possible, because its thermal insulation or endothermic effect will affect the authenticity of thermocouple measurements directly. The commonly used four thermocouple connection modes include:

B. Adhesive

Its features include connectability between thermocouple and non-immersed surface, high endurance of several cycles of reflow soldering temperatures, bad operatability after curing, and dfficult removal of residual adhesive. Suitable for continuously testing the fixed points.

C. High-temp adhesive tape

lts features include connectability between thermocouple and non-immersed surface and easy change of test points. As temperatures rises, its adhesion will drop and thermocouple will deviate from the test point, thus causing test errors. Thermocouple can not be fixed in a small place. Suitable for multiple test points.

D. Mechanical connection

Its connection is solid and reliable. It can not only stand repeated tests but also test narrow place. Its mechanical parts increase the heat capacity near the thermocouple and cause higher test cost. Suitable for high-density multiple-point continuous testing.

At present, what we use the most is high-temp solder. High-temp solder SMT-adhesive or high-temp adhesive tape is used to fix the test head of memory device's thermocouple to PCB's test points and then high-temp adhesive or glue is used to fix the thermocouple wire lest that its moving may affect measurement data. When soldering and curing, soldering points should as small and even as possible. Glue for fixing also should be as thin as possible.

SMT Production Line SMT Pick And Place Machine, PCB SMT Line,  Vision Stencil Printer,  SMT Stencil Printer, T6 Reflow Oven, Reflow Oven Price, Wave-Soldering Machine, Automated Pick And Place Packaging Machine, PCB Assembly Pick And Place Machine, Automatic Programable Pick And Place Manipulator, 4 Heads Pick And Place Machine, DIP Components Pick And Place Machinery, High Speed Pick And Place Module, R2R Pick And Place Dispense Rfid, Pab Conformal Coating Machine, Conformal Coating Machine PCB, Conformal Coating For PCB Machine, PCB Router Inalámbrico, PCB Circuito Router, PCB Drills And Routers, PCB Circuito Router CNC