A, mount components of the requirements of
1 the assembly position number component type, type, nominal value and polarity features mark to meet product assembly and schedule requirements.
2 post installed components to intact.
3 mount components welding end or pin is not less than 1/2 thickness to be immersed in the solder paste. General components for solder paste patch when the extrusion quantity (length) should be less than 0.2mm, the solder paste narrow spacing component patch when the extrusion quantity (length) should be less than 0.1mm.
The 4 components of the head or pins are aligned, centered and pad pattern. The reflow soldering have self positioning effect, so the component mount position to allow a certain degree of deviation. The allowable deviation range requirements are as follows:
(1) rectangular elements: design the right conditions in the PCB pad, element width direction of the welding end width more than 3/4 on the pads, in the length direction of the welding end elements and pad overlapping, pads extending part of greater than the height of the 1/3 welding end; a rotating deviation, the above components welding end width of the 3/4 must be in the pad. Mount should pay special attention to: element welding end must be in contact with the solder paste graphics.
(2) small outline transistor (SOT): X, Y, T (to allow rotation angle) is a deviation, but the pin (with toe and heel) must be in the pad.
(3) small outline integrated circuit (SOIC): X, Y, T (to allow rotation angle) is mount deviation, but must ensure that the device pin width 3/4 (including the toe and heel portions) in pad.
(4) quad flat package device and a super small packages (QFP): to ensure that the pin width of 3/4 in the pads, allowing X, Y, T (rotation angle deviation is small) mounted paste. Allow the pin of the toe pads a few out, but must have the 3/4 pin length on the pads, pin with the Department must also be on the pad.
Two, ensure that the three elements of
mount quality The 1 element is the correct
The number of components required assembly type, type, nominal value and polarity features labeling must comply with the map and schedule requirements of assembly products, can not be wrong position.
Accurate location of
2 (1) components of the head or pins and pads are aligned, centered graphic as far as possible, but also to ensure that components welding end contact paste graphics.
(2) the component mount position to meet the process requirements.