PCB assembly Mount Technology Basic requirements
PCB assembly Mount Technology Basic requirements can be summarized with three words: one to be posted accurately, to be posted well, three to be posted faster.
(1) accurately to
Paste accurately include the following meaning.
(1) elements correct: the bit number of components of each assembly type, model, nominal value and polarity of the signatures to meet the assembly drawing and schedule requirements can not be affixed to the wrong position.
The location is accurate: the tip of the components or lead on the position and angle and target graphics as much as possible aligned center. The current placement of the target, in addition to traditional land pattern on the PCB, as well as the actual printing of solder paste graphics outside the target.
(2) stickers well
Paste well, including the following meaning.
(1) does not damage the components: pick and place feeders, components, printed circuit boards error and Z-axis control failure and so may cause damage to the components, leading to the eventual placement failure.
②pressure (SMD height) suitable: SMD pressure (height) to the right, the pressure is too small patch components welding ends or pin floating sticky live components in the solder paste, solder paste, in passing, and reflow when the prone position; the Mounter pressure is too large, excessive amount of solder paste extrusion, is likely to cause the solder paste adhesion reflow prone bridge; too much pressure and even damage to components.
③ guarantee placement rate: placement machine parameter adjustment is unreasonable or poor performance of component placement, feeder and nozzle failure will cause the mount process components falling, a phenomenon known as "off-chip" or "butt". In actual production, the placement rate used to measure, when the placement rate is lower than the predetermined level, it must submit Amami reasons.
(3) stickers quickly
Usually a circuit board, there are tens of thousands of components, these components are posted up one of the basic requirements of placement speed production efficiency.
The mount speed mainly depends on the speed placement machine, as well as with the optimization of the placement process, set each application and management are closely related.