PCB design mistake 1: Overlap of weld pad
- The overlap of the pad (except for surface welding) means the overlap of holes. In drilling process, drill holes will be broken due to multiple drill holes, resulting in damage to holes.
- The two holes in the multi-layer plate overlap, such as one hole position for the isolatingpad, and the other for connection pad (thermal welding pad), so that the film is shown as isolate pad,lead to PCB damage.
PCB design mistake 2:The abuse of the graphic layer
- Some useless connections were made on some graphic layers, which were originally designed as four layers, but five layers of lines were designed, resulting misunderstanding in PCB design.
- It saves time in PCB designing the time graph. Taking Protel software as an example, we use Board line to draw lines, and use Board layer to draw marking lines.In this way, when we make film, we fail to select the Board layer and miss the connection.Or it will be short circuited due to the selection of Board layer’s annotation line, so the graphic layer should be kept intact and clear when PCB designing.
- Violation of conventional design, such as componentside at Bottom layer, welding side at Top layer, causing inconvenience.
PCB design mistake 3:The character setting
- The character covered SMD welding pad bring inconvenience to PCB’s E-test and component welding.
- The design of characters is too small, resulting in difficulties in screen printing. Too big characters overlap and difficult to distinguish.
PCB design mistake 4: The setting of the aperture of a single side pad
- The single side pad usually does not drill. If the hole needs to be marked, its apertures should be designed to be zero.If the value is designed, the hole coordinates will appear when drilling data is generated, and there will be a problem.
- Single side pad need drilling, should be specially marked
PCB design mistake 5:Draw pad with a filling block
- Usingfilling blocks to draw pads can be checked through DRC when designing lines,but it is not suitable for processing. Therefore, solder pad cannot directly generate solder resist data.When the solder mask printing, the area of the filling block will be covered by solder resist, resulting in the difficulty of device welding.
PCB design mistake 6:The ground and power layer are both thermal pad and the connection line
Because of the design of a power layer is negative layer,it is the opposite of the actual printed board,and all the wires are isolated lines, and the designer should be very clear.It should be careful when drawing several sets of power supply or isolation line of several kinds of land. It should not leave a gap, short the two sets of power, and do not block the area of the connection (a group of power is separated).
PCB design mistake 7:Definition of processing layer is not clear
- The single layer PCB design is on the TOP layer. If it is not stated, it is possible that the boards made are not equipped with devices.
- For example, a four layer board is designed with TOPmid1 and mid2 bottom four layers, but it is not placed in such order, which requires instructions.
PCB design mistake 8:There are too many filling blocks in PCB design, or filling blocks are filled with very thin lines.
- The films will miss data, and the data is incomplete.
- Because the filing block is drew on line by line in the process of plotting data processing, the amount of data produced will be quite large, which increases the difficulty of data processing.
PCB design mistake 9:Surface mounting pad is too short
This is for E-test, for too dense surface mount components, the distance between the feet is very small, and the pad is also quite thin,to install test pins, the upper and lower (left or right) positions must cross placed.If the pad design is too short, though it will not affect the components installation, it will make the test needle wrong.
PCB design mistake 10:The space between large area grids is too small
The edge between the large grid lines is too small (less than 0.3mm).In PCB manufacturing process, drawing process is prone to produce a lot of broken films on the board after finishing film development, causing breakage.