Liquid Dispensed Thermal Interface Materials (TIMs)

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Overview: This roundtable will discuss how effective thermal management is key to ensuring consistent long-term performance and reliability in electronic devices. With an increasing variety of electronic applications demanding smaller packaging, higher power, and lower cost, the need for innovative high performance, low cost thermal solutions continues to grow.
While there are many pad-form solutions available on the market, ever-increasing customer costs inherent with designing, documenting, shipping, storing, managing and assembling a multitude of die-cut parts in varying sizes continues to challenge design engineers. Join a panel of thermal management experts during this roundtable, where they will discuss how high performance liquids with unique characteristics are designed to improve overall thermal performance and reliability for thermal engineers.

Moderator:
Mark AmbergMark Amberg, Market Manager
Mark Amberg has been with The Bergquist Company, now a division of Henkel AE, for 18 years. He has held the roles of Automotive Market Manager and Automotive Business Development Manager for the last ten years.

Panelists:
Lonnie HelgesonLonnie Helgeson, Product Line Manager
Lonnie Helgeson is the Product Line Manager overseeing the Gap Filler product line for Henkel. His responsibilities include the identification and prioritization of strategic business opportunities to enhance the Liquid Thermal Interface Materials (TIMs) portfolio. With over thirty years of experience in the high tech market, he offers great insight in this fast paced globally competitive marketplace.

Ryan VerhulstRyan Verhulst, Scientist Engineer
Ryan Verhulst is a Research & Development engineer working on thermal interface materials. He has been with Henkel (formerly Bergquist) for 8 years. His education is in material science and he has experience working with ceramic powders, adhesives and sealants, and a wide variety of polymer chemistries.

John TimmermanJohn Timmerman, Scientist Engineer
John Timmerman is a senior research engineer with Henkel, whose main focus is high performance thermal interface materials, thermally conductive adhesives, and EMI absorbing materials. He has been with Henkel for 8 years and graduated from the University of Washington in 2003 with a Ph.D. in chemical engineering, where he researched thermal cycling of composite materials.

Tom HarrisTom Harris, Field Applications Engineer
Tom Harris, Field Applications Engineer, uses his Process Engineering, Automation and Customer Service Experience to assist Henkel AEH customers implement and troubleshoot Automated Liquid TIM Dispensing in their manufacturing processes. Working closely with his fellow Product Management Group Colleagues, he also directs Henkel’s Dispense Alliance Program, and Automated Dispensing Technical Knowledge-base. He holds a Six Sigma Green Belt as well as an M.B.A. and B.S. in Engineering.

The following are questions presented to the speaker by the attendees during the webinar, along with answers to each.

What is the typical cure time after application?
Answer: The cure time after application depends on the specific material being used and the temperature it is being cured at. Some materials will cure in 1min or less at room temperature, while others can take days to cure. In general, silicone gap fillers usually cure in 1-8hr at 25C.

If solvents are used to clean the component, will the TIM absorb the solvents causing change in its properties?
Answer: It is important that the substrates are clean, so we do suggest cleaning with a solvent. The solvent should be completely evaporated before the liquid material contacts the substrate. In general, the amount of solvent that could remain on a substrate won’t be enough to significantly change the TIM properties. With that being said, the best practice is to make sure all the solvent has evaporated.

What materials are TIMs made from?
Answer: The TIMs are typically a dispersion of thermally conductive ceramics in a polymer matrix. Metal oxide ceramics in conjunction with silicones are very common.

Are liquid TIMs reworkable? And can they be removed cleanly from devices / heat sinks?
Answer: Some liquid TIMs are more reworkable than others depending on their chemistry and mechanical properties. In general, most silicone gap filling materials will present some degree of reworkability.

Does this TIM bleed out over time and temperature gradient (i.e. silicone oil)?
Answer: Some TIMs, especially simple greases will show silicone bleed out over time. Most reactive gap filling TIMs are formulated to eliminate bleed out.

What is the price range of the dispensing machines?
Answer: Ranging from approximately $50,000 for desk-top units to $150,000 for automated pass through systems.

Are there challenges in dispersing thermal fillers?
Answer: Separation, wear, high viscosity and shear thinning are all issues in dispensing typical TIMs.

How are Liquid Dispense TIMs different than thermal grease?
Answer: Thermal grease is a type of liquid dispensable TIM. Thermal grease is non-reactive and is subject to pump out and dry out in an application. Most gap filling materials react to form an elastomeric material after dispensing while the thermal greases stay a liquid.

I need a TIM that doesn’t dry out for reasons I can’t go into right now. Is there such a TIM? And if so, can this liquid TIM have high performance?
Answer: Many liquid TIMs, particularly reactive gap fillers, won’t dry out over time. These TIMs are available with a wide range of thermal performance.