SMT reflow oven process requirement both end of Chip components solder welding plate should be independent. When the pad is connected with the ground wire of a large area, the cross paving method and the 45° paving method should be preferred. The lead wire from the large area ground wire or power line is larger than 0.5mm, and the width is less than 0.4mm; The wire connected to the rectangular pad should be drawn from the center of the long side of the pad to avoid an Angle.
See figure (a) for details.
Figure (a)
The wires between the SMD pads and the lead wires of the pads are shown in figure (b). The picture is the connection diagram of the pad and the printed wire
Figure (b)
Direction and shape of printed wire:
(1) The printed wire of the circuit board should be very short, therefore, if you can take the shortest, do not go complex, follow can easy not numerous, short not long. It is of great help to the quality control of PCB circuit board in the later stage.
(2) The direction of the printed wire shall not have sharp bending and acute Angle, and the Angle of the printed wire shall not be less than 90°. This is because it is difficult to corrode small internal angles when making plates. At too sharp outer corners, the foil can easily peel off or warp. The best form of turning is a gentle transition, that is, the inner and outer angles of the corner are the best radians.
(3) When the wire passes between two gaskets and is not connected with them, it should keep the maximum and equal distance from them; Similarly, the distances between the wires should be uniform and equal and kept to the maximum.
When connecting wires between PCB pads, the width of the wires can be the same as the diameter of the pads when the distance between the center of the pads is less than the outer diameter of the pads D; When the center distance between pads is greater than D, the width of the wire should be reduced. When there are more than 3 pads on the pads, the distance between the conductors should be greater than 2D.
(4) When connecting conductors between PCB pads, the width of conductors can be the same as the diameter of the pads when the distance between the center of the pads is less than the outer diameter D of the pads; When the center distance between pads is greater than D, the width of the wire should be reduced. When there are more than 3 pads on the pads, the distance between the conductors should be greater than 2D.
(5) Copper foil should be reserved for common grounding wire as far as possible.
In order to increase the peel strength of the liner, a non-conductive production line can be provided.
Post time: Jun-30-2021