The overlap pad

1, pad (except for the surface mounting pad) overlap, which means the vias overlap, the drill bit will be broken because of multiple drilling in the same area during the drilling process, then resulting in via damage.
2, 2 vias overlap in multilayer flexible PCB board, such as one via is isolation pad, the other via is connection pad (flower pad), so it will be performed to be isolation pad after negative film, then resulting in scrapped.

multilayer flexible pcb


Abuse of graph layer
1, there is some useless circuits connection on the certain pattern, it is designed to be over 5 layer board while it only should be 4 layer pcb board which make misunderstanding.
2, just to keep simple design, let’s take Protel for example, we layout all useful circuits by Board layer, while layout label circuit with board layer as well. And then when we export the Gerber data, there will be open circuit happened because we didn’t choose board layer and omitting the circuits; or there will be short circuit happened because of selecting the label circuit on board layer, so we must keep the original graph layer complete an clear.
3, contrary to conventional design, such as the component surface was designed in the Bottom layer, soldering surface design on Top layer, causing inconvenience.

Misplacing of the legend
1, the legend covers the SMD pads, causing inconvenience to the PCB on-off test and components soldering.
2, the legend was designed too small, resulting in difficulties in screen printing, or larger legends will be overlapped each other, it is difficult to distinguish.

Via diameter design for the single-sided pad
1, single-sided pad is generally no need drilling, it should be marked if drilling, and the diameter only should be designed to zero. Otherwise there will be the coordinate of the via when gerber file generated, this will lead to problems.
2, If drill on single-sided pad, there should be special mark.

Fill the pad with padding
The pads can be inspected by DRC when designing the circuit, but not ok for processing. Therefore, the solder pad can’t directly generate solder mask data. When the solder paste is applied, the pad area will be covered by the solder mask, resulting in the device is difficult to solder.

There is thermal pad and connection circuits on the ground layer
If the power supply was designed as thermal pads, the pattern on the ground layer and the real flex printed circuit boards is opposite, all the circuits are isolated, which the designer should be very clear about this. By the way here, layout a few groups of power or several of the isolation circuits should be careful, do not leave any gap, avoid the two groups of power short-circuit, also can’t block the connecting area (to force a group of power be separated).

The definition of processing is not clear
1, single-sided flexible PCB was designed on the TOP layer, if we process without any specification, top layer and bottom layer is opposite producing, so the finished printed circuit boards will be so difficult to solder.

single sided flexible pcb


2, for example, a four-layer flexible PCB boards layer order is: TOP, mid1, mid2 bottom, but the processing is not placed in this order, which requires to specify before manufacturing.

There is too much fill block or too thin fill block in flexible PCB design.
The Gerber date will be lost or incomplete if there are too much fill block or using to thin fill block, because we layout the fill block one by one when the gerber file generated, so the gerber data too large to deal with.

SMT pad is too short
This is for the on-off electric test, for the too dense surface-mount components with fine pitch, and the pads are very thin as well, when install the test pins, it must be up and down (left and right) staggered position, if the pad is designed is too short, although does not affect the components installation, but will not cross-set the testing pins.

Large area grid spacing is too small
In the PCB manufacturing process, the figure turn process after the film is easy to produce a lot of film attached on to the board, resulting in disconnection of the line between the large line of the same line between the edge is too small (less than 0.3mm).

A large area of copper foil is too close to the edge frame
A large area of copper foil from the outer frame should be at least ensure the spacing to be more than 0.2mm, because if milling to the copper foil will cause it turn up and then make solder-off problem happened.

Outline design is not clear
Some customers design the outlines without overlap in the Keep layer, Board layer, Top over layer, so the flexible PCB manufacturers is too difficult to determine which one should be the correct outline.

Graphic design is not uniform
It will cause the pattern plating uniform and affect the quality.

Using grid lines when the cooper area is too big to avoid foaming when SMT soldering.