Sil-Pad Design Guide All statements, technical information and recommendations herein are based on tests we believe to be reliable, and THE FOLLOWING IS MADE IN LIEU OF ALL WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING THE IMPLIED WARRANTIES OF MARKETABILITY AND FITNESS FOR PURPOSE. Sellers and manufacturers only obligation shall be to replace such quantity of the product proved to be defective. Before using, user shall determine the suitability of the product for its intended use, and the user assumes all risks and liability whatsoever in connection therewith. NEITHER SELLER NOR MANUFACTURER SHALL BE LIABLE EITHER IN TORT OF IN CONTRACT FOR ANY LOSS OR DAMAGE, DIRECT, INCIDENTAL, OR CONSEQUENTIAL, INCLUDING LOSS OF PROFITS OR REVENUE ARISING OUT OF THE USE OR THE INABILITY TO USE A PRODUCT. No statement, purchase order or recommendations by seller or purchaser not contained herein shall have any force or effect unless in an agreement signed by the ofcers of the seller and manufacturer. Registered Firm ISO 9001:1994 Certicate QSR-219 QS-9000 Third Edition Certicate Number, QSR-QS-017 2000-2001 Rev. 060100 Copyright The Bergquist CompanyThe Bergquist Company established the standard for contamination of elastomeric thermally conductive insulation material with the the solder. development of Sil-Pads over 20 years ago. Sil-Pads were Cleaning baths developed as a clean, grease-free alternative to mica and grease. must also be Now, a complete family of materials is available to meet the avoided to prevent diverse and changing requirements of todays design engineer. wash-out of the interface grease, MICA AND GREASE causing a dry joint Mica insulators have been in use for over 30 years and are still and contamination commonly used as an insulator. Mica is inexpensive and has of the bath. excellent dielectric strength, but it is brittle and is easily cracked or Assembly, soldering broken. Because mica used by itself has high thermal impedance, and cleaning thermal grease is commonly applied to it. The grease ows easily processes must be performed in one process while the greased and excludes air from the interface to reduce the interfacial insulators are installed off-line in a secondary process. If the grease thermal resistance. If the mica is also thin (2-3 mils), (50-80 m), is silicone based, migration of silicone molecules occurs over time, a low thermal impedance can be achieved. drying out the grease and contaminating the assembly. Silicone migration onto electrical contacts can result in pitting of the However, thermal grease introduces a number of problems to contacts and loss of electrical conductance. For this reason, silicone the assembly process. It is time-consuming to apply, messy, and based, thermal grease has not been used in telecommunications difcult to clean. Once thermal grease has been applied to an systems. electronic assembly, solder processes must be avoided to prevent Why Choose Sil-Pad Thermally Conductive POLYIMIDE FILMS Polyimide lms can also be used as insulators and are often combined with wax or grease to achieve a low thermal impedance. These polyimide lms are especially tough and have high dielectric strength. Sil-Pad K-4 , K-6 and K-10 incorporate polyimide lm as the carrier material. CERAMIC INSULATORS Other insulation materials include ceramic wafer insulators which have higher thermal conductivity than mica. They are often used thicker (20-60 mils), (.5 to 1.5 mm) to reduce capacitive coupling while maintaining a low thermal impedance. Drawbacks to ceramic insulators are high cost and they are rigid like mica and crack easily. Also, ceramic beryllia use requires careful handling since inhalation of beryllia dust can cause lung inammation (berylliosis). At Bergquist s Cannon Falls, MN manufacturing facility, a Sil-Pad material runs through a 3-story coating press.