Flex Circuits Design Guide
32Pages

Precision Flexible Circuitry for Medical Implants & Diagnostics, Defense, Aerospace & Other Critical ApplicationsDesign Guidelines for Highly Reliable Flexible Printed Circuits Optimized for Manufacturability >

Compared to discrete wiring, or ribbon cable, a flex circuit offersa customized repeatable routing path within your assembly. This gives you dependability where you need it. A flex circuits longevity can reduce service calls. > ҕ Sp a c e a nd w e i g ht r e duction : A single flex circuit can replace sev-eral hardboards, cables, and connectors. Standard practice for flex boards is to cover the conductors withpolyimide. This dielectric layer protects your circuits far beyond the capability of simple soldermask. Other base and cover materials are available for a broad range of ambient...

Ri g id-f le x Pin s Fin e l in es > Hybrid hardboard/flex circuits can have up to sixteen layers. They replace bulky wire harnesses with compact, robust design. Minco can braze or solder pins to circuits, either through holes or as extensions to conductors. 0.002" conductors and spaces are possible. Stiff e n e r s Conn e ctor s Shi el din g > An inexpensive alternative to rigid-flex. Built-in connectors speed your assembly.Optional epoxy potting seals between the circuit and connector. Solid or patterned shield planes reducenoise and control impedance of signallines. Use matched impedance...

IPC 6013, MIL-P-50884 - Type 4ՕTwo or more conductive layers with either flexible or rigid insulation material as insulators between each one; outer layers may have covers or exposed pads.Rigid-flex has conductors on the rigid layers, which differentiates it from multilayer circuits with stiffeners. Plated through-holes extend through both rigid and flexible layers (with the exception of blind and buried vias). Rigid-flex costs more than a standard circuit with stiffeners.ՕAccess holes or exposed pads without covers may be oneither or both sides. Vias or interconnects can be fully covered...

Circuit s iz e / s t a nd a rd p a n el s iz e: 10.5 җ 22" max./12 24", 16.5 ח 22" max./18 24", 267 x 559mm max./305 x 610mm, 419 x 559mm max./457 x 610mm P la tin g m e thod s: Panel, selective, thruhole, blind via, buried via L a y e r s: 16 maximum. P la tin g m a t e ri als: Solder, hard gold, soft gold, tin, nickel, elec-troless nickel with immersion gold (ENIG), OSP Conductor width/ s p a c e: 0.0015ה(0.038mm) minimum /0.0015(0.038mm) minimum. > Ho le di a m e t e r ( p la t e d ): 0.002Ԕ(0.051mm) minimum. In s u la tion r es i s t a nc e: 100 M minimum @ 25C (77аF), assuming 0.010"...

When specifying testing, consider your needs carefully. Over-specification can greatly increase circuit cost. Minco encourages electrical testing. It is required on all multilayer, rigid-flex, and factory-formed circuits that are fabricated to MIL-P 50884, and certain classes of IPC-6013.See the table below for information on MincoҒs test capabilities.Minco can meet your marking requirements. Our legend marking system offers silkscreen-like printing usinga durable white ink that meets IPC-TM-650 industry standards. This system allows us to incorporate date code and serial num- bering, along...

The nomograph on the facing page will help you determine themaximum allowable current capacity (in amperes) of a conduc- tor. Reprinted from IPC-2221 (and MIL-STD-2118), the nomo- graph shows current for various conductor thicknesses, width, and temperature rises. A ss umption s > 1.The nomograph is valid only for conductors with a polyimidecover layer җ not exposed conductors.2.The conductor thickness includes copper plating. Be awarethat plating may add 0.0005" (13m) to 0.0014" (36յm) of thickness. Selectively plated circuits do not have significant plating over conductors. The nomograph...

Example # 1: A current of 1 amp with ҽ oz. copper and 30Ctemperature rise will require a conductor width of 0.040Д.Example # 2: A 0.140" wide conductor etched from 1 oz. copper(0.0014") will produce a temperature rise of 10C at 2.7 amp. 34323028262422 Note: square mil = 6.4516x10^-4 square millimeter 13 size="-1">

D e fin e circuit p a r a m e t e r s b y a pp l ic a tion Sp e ci al con s id e r a tion s for ri g id-f le x > It may be helpful to use a paper template to represent the circuit.Experiment with bending and forming the template to optimize shape and fit. When designing the final shape, consider how the circuits will lay out on a processing panel (nestingӔ). The greater the number of circuits per panel, the lower the cost.Another consideration concerns rigid-flex. While Minco is capa-ble of building a traditional rigid-flex board for you it may not be your best choice. Multilayer or...

B e nd r a diu s ( f le xi b i l ity ): Single-layer:6 circuit thickness (minimum) Double-layer:12 ח circuit thickness (minimum) Multilayer:24 circuit thickness (minimum)Circuit thickness is approximately 0.006" (0.150mm) per layer. Single-layer circuits are the best choice for dynamic (flex-in-use)applications. Two or more layer circuits are best suited to static applications, with flexes only during installation.Several problems can arise when a circuit is bent sharply.Compression can cause wrinkles in the cover coat on the inside of the bend.Stretching can result in tears in the cover...

G e n e r al r e quir e m e nt s for p a d s , a cc ess ho lesa Vi as nd a nnu la r rin gs > Minco can provide circuits with covers that have noaccess holes exposing the vias (called 'tented vias'). Minco can also provide blind and buried vias in multi- layer and rigid-flex circuits. Blind vias connect the top or bottom conductor layer to adjoining layers, but the via does not extend through all layers. A buried via only connects internal layers and is not exposed in the finished circuit. Blind and buried vias increase circuit cost, but they free up space for additional conductors on the...