Glossary

Ri g id-f le x T ea r s top s
A circuit containing both rigid and flexible areas. The rigid lay-ers have conductors and plated through-holes connecting them to other layers. Copper, polyimide, or Teflon guards that are located in the innercorners of polyimide-insulated flex circuits in order to prevent propagation of tears. S ele cti ve p la tin g Throu g h-ho les
A method of plating flex circuits so that only the circuit’sthrough-holes and surrounding pads are plated. This greatly adds to a circuit’s flexibility. Holes that are drilled through the layers of a flex circuit in orderto have component access to those layers. Connection from one layer to the next is provided by plating the through-hole walls with a thin layer of copper. St a tic a pp l ic a tion
The use of a flex circuit in an environment that requires flexingduring installation and maintenance, but not in operation. Trim l in e
The area defined by a design engineer as the final cut-out areaaround a flex circuit. St eel ru le di e ( SRD )
T rim Line A tool used in a punch press, consisting of steel cutting bladesin a pattern, embedded into a maple plywood base. Un b ond e d a r eas
A flex circuit design technique that involves providing an insulat-ing layer between every conductive layer of a flex circuit, but with no adhesive bonding between the insulating layers in cer- tain areas of the circuit. This technique improves circuit flexibility. Stiff e n e r
Flexible or rigid pieces of material (usually polyimide or FR-4)added to flex circuits to reinforce them for component mount- ing. There are no conductors on stiffeners, as compared to rigid- flex circuits. Vi a
A plated through-hole with no cover access holes that providesconnection for internal layers. Su bs tr a t e
A layer of insulator bonded on one or both sides with foil. T a n ge ncy
A condition that occurs when the edge of a stiffener or coveraccess hole is flush with the edge of a through-hole. T hrough-Ho l e Stiffener 30