Design Rules

Generally the same rules govern the design of flexible and rigid PCB's. Listed below are some factors relating solely to flexible boards.

• Pad design should take into account the method of anchorage. On unplated boards this should be by adding tags to the pad. For plated through product the through hole plating will act as the anchor.
• Traces should be tapered into pads by means of a teardrop. Ninety degree bends in traces should be avoided.
• Traces should be routed tangentially between holes to gain maximum space. Where possible route traces on the component side and maximise solderable land on the solder side.
• Avoid square or rectangular holes where possible as these will increase cost. This applies to the covercoat as well as the board itself.
• Maximise land around via holes.
• Where the circuit is required to bend, tracking should follow the direction of the bend. Do not route tracks tangentially to the bend and try to design the circuit to be single sided in this area.
• Generally, covercoat apertures should be designed to be smaller than the component lands by 0.2mm diameter (approximately). When considering the hole size in relation to the solderable land area the same rules as those used for rigid PCB apply.
• Plane and copper fill areas should be crosshatched to improve flexibility.
• Allow a nominal 0.5mm clearance from the profile edge to the nearest conductor.