FLEX CIRCUITS DESIGN GUIDE

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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 to attain with conventional wiring. The flexibility of materials constructing a flex circuit allow it to be more compliant than rigid circuits, so it is not always necessary to specify tight tolerances across all dimensions. Trimming Each trimming method has advantages and disadvantages. Routing and laser trimming provide hard tooling (punch and die) tolerances 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 incremental increase in cost. Hard tooling (punch and die) is recommended for tight tolerances, complex circuits, and/or high quantity. For more specific information on SRD, punch-and-dies and CMD, see the Glossary at the end of this guide. Circuit Outline dimensions (profile tolerance) Hole-to-border dimensions Cluster to dimension in inches(mm)† SRD CMD Punch and die /laser SRD CMD Punch and die /laser cluster§ 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. Solder thickness 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 at least five times wider than they are thick. Tolerances for conductor width depend on whether the copper is plated or unplated. Copper thickness Plated copper Unplated copper 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
Standard Design Recommendations Materials This table lists the materials and material thicknesses that Minco has available. Minco’s standard materials are in boldface. If the material or thickness is not listed, consult Minco at 763.571.3121. Material function Material type Sizes/thickness available Flexible insulator Kapton* and other polyimide films † 1/2 mil (12.5μm), 1 mil (25μm), 2 mil (50μm), 3 mil (75μm), 5 mil (125μm) Rigid substrate (rigid-flex) FR-4 Variety of thicknesses between 0.003" (0.08mm) and 0.125" (3.18mm) Polyimide Variety of thicknesses between 0.003" (0.08mm) and 0.125" (3.18mm) Conductor Copper 1/4 oz. (9μm), 1/3 oz. (12μm), 1/2 oz. (18μm), 1 oz. (35μm), 2 oz. (71μm), 3 oz. (107μm), 5 oz. (175μm), 7 oz. (254μm), 10 oz. (356μm) Different forms of copper Half-hard, rolled-annealed, electro-deposited Beryllium copper 3 mil (75μm): half-hard and quarter-hard 4 mil (100μm): half-hard Cupro-nickel (70/30 alloy) 0.625 mil (15μm), 0.9 mil (22μm), 1.3 mil (33μm), 1.9 mil (48μm), 2.3 mil (58μm) Nickel 2 mil (50μm), 3 mil (75μm), 5 mil (125μm) Silver epoxy ‡ Adhesive § Modified acrylic 1/2 mil (12.5μm), 1 mil (25μm), 2 mil (50μm), 3 mil (75μm), 4 mil (100μm) Modified epoxy 1/2 mil (12.5μm), 1 mil (25μm), 2 mil (50μm), 3 mil (75μm), 4 mil (100μm) Phenolic Butyral 1 mil (25μm) Pressure-sensitive adhesive (PSA) 1 mil (25μm), 2 mil (50μm), 5 mil (125μm) Pre-impregnated material: FR-4, polyimide 2 mil (50μm), 8 mil (200μm) Stiffener Copper, Aluminum, and other metals Variety of thicknesses available Polyimide glass FR-4 See “Rigid substrate/Polyimide glass” above Variety of thicknesses between 0.005" (0.13mm) and 0.125" (3.18mm) Polyimide 1/2 mil (12.5μm), 1 mil (25μm), 2 mil (50μm), 3 mil (75μm), 5 mil (125μm) * Kapton is a registered trademark of DuPont for polyimide. Dielectric strength of plain Kapton film is 3500-7000 volts/mil (0.025mm) depending upon material thickness. Kapton/modified acrylic has a dielectric strength of 3500 volts/mil (0.025mm) and a temperature rating of -65 to 150°C, although circuits will discolor after long-term exposure at 150°C. For special applications, Minco can use an adhesive that will withstand temperatures of 150°C continuous, and 200°C short-term. † Other polyimide films are available for special applications. ‡ Material is applied as an alternative to standard copper layers. § In general, Minco recommends 0.001" (25μm) of adhesive on the cover material per 1 oz. (35μm) of copper (including plated copper). There may be special circumstances where more is required. Consult Minco for details. 19
Page 1 and 2: FC302(A) FLEX CIRCUITS DESIGN GUIDE
Page 3 and 4: How to Get Started 1. Understand Ho
Page 5 and 6: Design Options Rigid-flex Hybrid ha
Page 7 and 8: Design Guidelines Manufacturing a f
Page 9 and 10: Design Guidelines Circuit types Rig
Page 11 and 12: Minco’s General Capabilities Test
Page 13 and 14: Minco’s General Capabilities Cond
Page 15 and 16: Standard Design Recommendations How
Page 17: Standard Design Recommendations Hol
Page 21 and 22: Value Added Design Options Stiffene
Page 23 and 24: Value Added Design Options Custom a
Page 25 and 26: Request a Quote Artwork checklist M
Page 27 and 28: E2E — Engineer to Engineer Early
Page 29 and 30: Glossary Impedance The measurement
Page 31 and 32: Next Steps Minco welcomes the oppor

FLEX CIRCUITS DESIGN GUIDE

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