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Because good solder paste printing, no welding assembling PCB board can't fixed thermocouple test, so you need to use the welded actual product for testing. In addition, the test sample can not

by:Rigao      2020-03-29
A, select test points: according to the complexity of the PCB assembly board and number of channels in the collector ( General collector has 3 ~ 12 test channels) , the choice of at least three or more can reflect high on a board assembly (PCB surface The most hot) , medium and low ( The most cold spots) The temperature of the representative test points. The highest temperature ( Hot) Generally in the middle of the chamber of a stove or furnace, few components or components and small components; The lowest temperature ( Cold spots) General in the large components ( Such as PLCC) , copper in large cloth, transmission guide or furnace hall edge location, blowing hot air convection. Second, fixed thermocouples: using high temperature solder ( Sn- 90 pb, melting point solder of more than 289 ℃), The test end of dogan thermocouple respectively welding in the test point ( Solder joints) , before welding of solder in the solder joints must be clean; Or the test end of thermocouple respectively with high temperature adhesive tape paper sticking to the PCB various temperature test point location, no matter adopt what kind of way fixed thermocouples are required to ensure weld, cements, clip. The other end of the three, the thermocouple insertion machine mesa of 1, 2, respectively. . Jack position, or inserted into the collector outlet, pay attention not to reverse polarity. Thermocouple number and remember each thermocouple on the surface mount board relative position, shall be recorded. Four, will be measured on the surface of PCB assembly board placed at the entrance of reflow welding machine transmission chain/net belt ( If you use the collector, the collector should be placed behind the surface of the PCB assembly board, just to keep some distance, about 200 mm) above The test program, and start the KIC temperature curve. Five, with the operation of the PCB, drawing on the screen, Display) The real time curve ( Equipment with KIC test software) 。 Six, when PCB run after cooling zone, pulls the thermocouple line will drift back PCB assembly board to complete a test process at this time, displayed on the screen full of temperature curve and peak temperature/timetable ( If the collector temperature curve is used, the PCB from the reflow soldering furnace exit and collector, and then through the software read temperature curve and peak temperature schedule) 。
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