As mentioned earlier, if you can use SMD components, you don't need to insert them directly. Then the selection basis of in-line components is: if it can be printed automatically by machine (AI), manual insertion (MI) is not selected.

General SMD components can be mounted by SMT machine. There are no special requirements on distance, height, shape and so on, so they can be pasted.

AI technology is a little more troublesome. Some components can't be AI, and the components that are usually taped can be AI (otherwise, why tape is convenient for AI). Attached is a training on AI process. When you know this, pay attention to the spacing of components, the size of components, the distance between pins, and the aperture of pad during layout.

The following is an example. The figure is a panel. First, introduce the positioning hole of AI. For the round hole with 4mm in the lower left corner, it is required to be 5mm away from the left and lower edge. The positioning hole on the lower right side is an elliptical hole with a distance of 4 * 5, so long as the distance is 5mm from the lower edge. The upper and lower plate edges are for PCBA to be placed on the conveyor belt for wave soldering; Sometimes, tin water will come up from the front plate edge, which is mainly used to block tin, and 5mm is enough; the back plate edge can not be needed; the four arrows indicate the direction of PCBA entering the furnace when passing through the furnace.

Generally speaking, if the board is too small, it will be assembled into a large board for processing. In the picture, four pieces are put together, and then three pieces are put together. The purpose of this is to facilitate the test, because there are many wiring harness in the board (each small board has 6 wiring harness), so only four small pieces can be tested together.

Take a look at one of the small boards. There are two positioning holes on it for easy testing. There is no requirement for size and position. Generally, 3mm is enough. There is also a SMT positioning hole, which can be placed on the edge of the board. The disadvantage is that the SMT will not be convenient in case of fracture of the panel. If there is an oblique component in the figure, AI is not allowed.