DESIGN GUIDE Version 1.0 Printed Polymer Design Guide www.we-online.com Keypads Switches P-Cu Cu P-P P-P P-LSL P-LSL P-P P-P P-Cu P-Cu D P-P P-LSL P-LSL P-D Copper width Overlap polymer to copper Distance to other electrical potential Solder mask clearance P-Cu Cu ≥ 0.20 mm Overlap polymer to copper P-Cu ≥ 0.15 mm P-Cu ≥ 0.15 mm Distance to other electrical potential P-P ≥ 0.5 mm P-LSL ≥ 0.25 mm P-D ≥ 0.15 mm D ≥ 0.3 mm P-P ≥ 0.50 mm Solder mask clearance P-LSL ≥ 0.25 mm Distance between carbon and dielectric Copper thickness (total) ≤ 50 µm Dielectric width Contact resistance ≤ 20 Ω Copper thickness (total) ≤ 50 µm Contact resistance ≤ 20 Ω Basics The print is used as a passivation of the copper to prevent from oxidization and to achieve a constant contact resistance during the lifetime. The contact resistance is influenced by the contact material and the contact pressure and is normally < 20 Ω. Two areas with a different electrical potential are shorted by conductive rubber mats or metal contact springs. 02 www.we-online.com Switches are used with sliding contacts; two contact areas of different electrical potentials are shorted by the slider. Resistors Outer Layers Resistors Inner Layers Ag-Cu P-Ag P-LSL Ü blocked for vias B B P-Cu L L Resistor length L ≥ 2 mm Resistor width B ≥ 1.5 mm Ag-Cu ≥ 0.25 mm Overlap resistor to silver P-Ag ≥ 0.15 mm Solder mask clearance P-LSL ≥ 0.25 mm Overlap polymer to copper Ü 0.20 mm Overlap polymer to copper P-Cu ≥ 0.15 mm Overlap silver to copper Copper thickness (total) ≤ 50 µm Distance to other electrical potential ≥ 0.5 mm Resistor values Resistor tolerance Dissipation at environmental temperature: ≤ 40°C 100 Ω – 750 kΩ +/- 30 %* ≤ 50 mW/mm2 * +/-5 % with laser trimming Basics Printed resistors are built by printing a polymer ink with a specific conductivity between to copper pads. The thickness of the resistors is 20 µm in standard. With an adjustment of the resistors by laser trimming a lower tolerance can be reached. 03 Special Applications Potentiometer Heating Resistor Surface Finishing HAL HAL lead-free ENIG Immersion Tin Keypad – Switches – Resistor on outer ayer – Resistor on inner layer Potentiometer – – – Application Heating resistor on outer layer – – – Heating resistor on inner layer Contact plug – Shielding print – – – Non-standard layout configuration can be checked for feasibility by our product management. Feasibility is possible in many cases. Würth Elektronik Schopfheim GmbH & Co. KG Circuit Board Technology An der Wiese 1 79650 Schopfheim · Germany Tel. +49 7622 397-0 Fax +49 7622 397-122 [email protected] www.we-online.com DIENECK ARPRINZEN 1014.FLY Contact us!