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Common Knowledge of Pick and Place Machine and SMT Production (3)


Latest company news about Common Knowledge of Pick and Place Machine and SMT Production (3)

31. The resistor whose silk screen (symbol) is 272 has a resistance value of 2700Ω, and the symbol (silk screen) of a resistor with a resistance value of 4.8MΩ is 485;


32.The silk screen on the BGA body contains information such as the manufacturer, manufacturer's material number, specification and Date code/(Lot No);


33.The pitch of 208pinQFP is 0.5mm;


34.Among the seven methods of QC, the fishbone diagram emphasizes the search for causality;


35.CPK refers to: Process Capability under Current Actual Conditions;


36.The flux starts to volatilize in the constant temperature zone for chemical cleaning;


37.Ideal cooling zone curve and reflow zone curve mirror image relationship;


38.The solder paste of Sn62Pb36Ag2 is mainly used on ceramic boards;


39.Rosin-based flux can be divided into four types: R, RA, RSA, RMA;


40.The RSS curve is heating→constant temperature→reflux→cooling curve;


41.The PCB material we are using is FR-4;


42.The PCB warpage specification does not exceed 0.7% of its diagonal;


43.Laser cutting by STENCIL can be reworked;


44.At present, the BGA ball diameter commonly used on computer motherboards is 0.76mm;


45.The ABS system is an absolute coordinate;


46.The error of ceramic chip capacitor ECA-0105Y-K31 is ±10%;


47.The PCB of the computer currently in use is made of: glass fiber board;


48.The diameter of tape and reel for SMT parts packaging is 13 inches and 7 inches;


49.The opening of the SMT general steel plate is 4um smaller than that of the PCB PAD to prevent the phenomenon of bad solder balls;


50.According to the "PCBA Inspection Specification", when the dihedral angle > 90 degrees, it means that the solder paste has no adhesion to the wave soldering body;


51.After the IC is unpacked, if the humidity on the display card is greater than 30%, it means that the IC is damp and absorbs moisture;


52.The weight ratio and volume ratio of tin powder and flux in the solder paste composition are correct 90%:10%, 50%:50%;


53.The early surface mount technology originated from the military and avionics fields in the mid-1960s;


54.At present, the contents of Sn and Pb in the most commonly used solder paste for SMT are: 63Sn 37Pb; the eutectic point is 183°C;


55.The feeding distance of the common paper tape tray with a bandwidth of 8mm is 4mm;


56.In the early 1970s, a new type of SMD appeared in the industry, which was a "sealed footless chip carrier", often replaced by LCC;


57.The resistance value of the component marked 272 should be 2.7K ohms;


58.The capacitance of 100NF components is the same as that of 0.10uf;


59. The most commonly used electronic component material for SMT is ceramics;

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