Wave soldering process, component placement direction requirements

PCB component placement requirements.

PCB layout rules should be strictly referenced

(a), the specific requirements are as follows:

1. Orientation of component placement

A. Placement of components Consider wiring, assembly, welding, and maintenance as much as possible. Components on the PBA require as much as possible a uniform orientation, and components with positive and negative polarity must have a uniform orientation.

B. For the Wave soldering process, the component placement direction is shown in Figure:

Due to the shadowing effect of Wave Soldering, the component direction is 90° to the welding direction, and the wave soldered surface element is

The height limit is 4mm.

C. For the hot air reflow process, the orientation of the components has little effect on the welding.

D. For PCBs with components on both sides, larger and denser ICs, such as QFP, BGA, etc., are packaged on the top layer of the board. The plug-in components can only be placed on the top layer, and the other side of the packaged components (bottom layer). Only small components and patch elements with fewer pins and loosely arranged components can be placed. The columnar surface mount device should be placed on the bottom layer.

E. For the structure of the vacuum fixture, the maximum height of the components on the back of the board shall not exceed 5.5mm; if a standard acupressure test fixture is used, the components on the back of the board shall not exceed 10mm.

F. Considering the actual working environment and its own heat, components should be placed in consideration of heat dissipation factors.

Note:

1. The arrangement of components should be conducive to heat dissipation. If necessary, fans and heat sinks are used. It is especially important for small-size, high-calority components and heat sinks.

2. Heat sinks can be used to dissipate heat from components such as high-power MOSFETs. Do not place heat-sensing components around these components. If the power is particularly large and the heat is particularly high, heat sinks can be added for heat dissipation.