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China Pcba Manufacturing
Oct 19, 2017

Industry industrial electronics tape feeder for smt production lines smt pcba motherboards assembly electronics contract manufacturing services OEM CEM EMS experience company—China Shenzhen Topscom

Component placement is an electronics manufacturing process that places electrical components precisely on printed circuit boards (PCBs) to create electrical interconnections between functional components and the interconnecting circuitry in the PCBs (leads-pads). The component leads must be accurately immersed in the solder paste previously deposited on the PCB pads. The next step after component placement is soldering.

placement process:

Basic placement sequence generally includes: board indexing, board registration, fiducial vision alignment, component pick-up, component centering/vision inspection, component placement and board indexing. Component pick-up, component centering/vision inspection, component placement are repeated for each component. Sometimes, adhesive dispensing and on-line electrical verification are also included in the sequence.

Through the process of board indexing, the stencil-printed PWB is loaded to the appropriate position. Fiducial marks, or also known as fiducial markers, provide common measurable points for all steps in the assembly process. There are many types of fiducials. Global fiducials are used to locate the position of all features on an individual printed circuit board. When multiple boards are processed as a panel, the global fiducials may also be referred to as panel fiducials if used to locate the circuits from the panel datum. Local fiducials are used to locate the position of an individual land pattern or component that may require more precise location, such as a 0.02 in (0.51 mm) pitch QFP.

Board is located by identify global fiducials on the PWB. Then the feeders pick up and center the components at a known distance from the component. Higher placement accuracy requires help from local fiducials visualized by optical or laser sensors. Vacuum pickup head removes components from feeders. In the end, the component is placed at the correct X, Y and theta location with all leads ion the correct pads in contact with solder paste. The PWBs with all components correctly placed will then move to the reflow process.