PCB Engineers Pay Attention To Which Details Are Helpful

There is a saying that "details determine success or failure", the distance between the novice and the old PCB engineer is often reflected in some details.

1. Pay attention to the direction and distance of the components placed on the edge of the PCB board

Since PCBs are generally made of puzzle pieces, devices near the edge need to meet two conditions.

The first condition is parallel to the cutting direction (so that the mechanical stress of the device is even, when the patch is to be split, the force directions of the two pads may be different, which may cause the element and pad to fall off)

The second condition is that the device cannot be arranged within a certain distance (to prevent damage to the components when the board is cut)

2. Pay attention to the spacing between the patches

The spacing between chip components is an issue that engineers must pay attention to when laying out. If the spacing is too small, solder paste printing and avoiding soldering are very difficult.

The recommended distance is as follows

Device distance requirements between patches:

Same kind of device: ≥0.3mm

Different kind of devices devices: ≥0.13 * h + 0.3mm (h is the maximum height difference of neighboring components)

The distance between components that can only be patched manually: ≥1.5mm

The above suggestions are for reference only, according to the PCB process design specifications of their respective companies.

3. Pay attention to the distance between the wires or components and the edge of the board

Note that the leads or components cannot be too close to the edge of the board, especially in the single-sided board. The general single-sided board is mostly a paper board, which is easy to break after being stressed. If you connect or put components on the edge, it will be affected.

4. Placement of IC decoupling capacitors

Decoupling capacitors need to be placed near the power port of each IC, and as close to the power port of the IC as possible. When a chip has multiple power ports, decoupling capacitors must be arranged for each port.

5. The treatment of line corners

Normally there will be a change in thickness at the corners of the line, but when the line diameter changes, some reflections will occur. The corner method is the worst for the thickness of the line, the 45-degree angle is better, and the rounded corner is the best. However, the rounded corners are more troublesome for PCB design, so it is generally determined by the sensitivity of the signal. Generally, a 45-degree angle is enough for signals. Only those very sensitive lines need to use rounded corners.

6 .It is best not to hit the pad on the via, otherwise it will easily lead to solder leakage.

7. The width of the lead on both sides of the component pad should be the same.

8. If the lead is smaller than the pad of the plug-in, you need to add teardrops.

Adding teardrop has the following benefits:

1. Avoid the sudden decrease of the signal line width and cause reflection, which can make the connection between the trace and the component pad tend to transition smoothly.

2. Solve the problem that the connection between the pad and the trace is easily broken by the impact force.

3. The installation of teardrops can also make the PCB circuit board look more beautiful.