Standard Design Recommendations

Tolerances

You are not limited to the tolerances listed in this section. Tighter tolerances are achievable, but often at a higher cost. Accordingly,more relaxed tolerances will typically cost less. Even with relaxed tolerances, a flex circuit will have a uniformity that is impossible toattain with conventional wiring. The flexibility of materials constructing a flex circuit allow it to be more compliant than rigid circuits, soit is not always necessary to specify tight tolerances across all dimensions.

Trimmin g

Each trimming method has advantages and disadvantages. Routing and laser trimming provide hard tooling (punch and die) toler-ances for small quantities of circuits. Laser trimming is also capable of complex cutouts not feasible with other methods. Steel rule dies(SRD) are best for intermediate quantities and tolerances. Chemical milled dies (CMD) offer tighter tolerances than SRDs for an incre-mental increase in cost. Hard tooling (punch and die) is recommended for tight tolerances, complex circuits, and/or high quantity. Formore specific information on SRD, punch-and-dies and CMD, see the Glossary at the end of this guide. Circuit dim Out l in e dim e n s ion s ( profi le to le r a nc e) Ho le -to- b ord e r dim e n s ion s C l u s t e r toc e n s ion ininch SRD CMD Punch a nddi SRD CMD Punch a nddi l u s t e r§ es( mm ) † e / lase r e / lase r 1 ±0.015 (0.38) ±0.010 (0.25) ±0.003 (0.08) ±0.015 (0.38) ±0.010 (0.25) ±0.007 (0.18) ±0.003 (0.08) 5 ±0.020 (0.50) ±0.015 (0.38) ±0.007 (0.18) ±0.020 (0.50) ±0.015 (0.38) ±0.012 (0.30) ±0.007 (0.18) 10 ±0.025 (0.63) ±0.020 (0.50) ±0.012 (0.30) ±0.025 (0.63) ±0.020 (0.50) ±0.017 (0.43) ±0.012 (0.30) 15 ±0.030 (0.76) ±0.025 (0.63) ±0.017 (0.43) ±0.030 (0.76) ±0.025 (0.63) ±0.022 (0.55) ±0.017 (0.43) 20 ±0.035 (0.88) ±0.030 (0.76) ±0.022 (0.55) ±0.035 (0.88) ±0.030 (0.76) ±0.027 (0.69) ±0.022 (0.55)
† Round circuit to next highest increment.§ Represents from a group of holes to a group of holes. Holes within a group will have a tolerance of ±0.003" (0.08mm). Note: Dimensional tolerances are given in inches. See Glossary for definition of profile tolerance.

So l d e r thic k n ess

Minco follows IPC-6013 requirements of coverage and solderability for solder coatings.

Conductor width, thickness, and spacing

See the nomograph on pages 12 – 13 for calculating the necessary conductor width and spacing. Minco can provide a 0.004" (0.10mm)minimum conductor width/spacing (0.0025"/0.063mm minimum at higher cost) on 1 oz. (25µm) copper and 0.005" (0.13mm) minimum conductor width-spacing on 2 oz. (50µm) copper (for thicker copper, consult Minco). For best producibility, design circuit conductors atleast five times wider than they are thick.Tolerances for conductor width depend on whether the copper is plated or unplated. Copp e r thic k n ess P la t e d copp e r Unp la t e d copp e r ½ oz. ±0.001" (25µm) ±0.001" (25µm) 1 oz. ±0.002" (50µm) ±0.001" (25µm) 2 oz. ±0.003" (75µm) ±0.002" (50µm) 3 oz. ±0.004" (100µm) ±0.003" (75µm) 18