Below are the questions asked during the event, along with their respective answers.
Q: Do you see the trend in moving to Pads form or liquid form in the future 5G arena for the thermal applications?
A: The trend will depend on the specific application within the 5G application. The three criteria that customers will be looking at are (a) Thermal solution (b) Ease of production and rework (c) Cost. Personally, my opinion is moving towards more to 1 part Gel and Pads to meet the thermal impedance requirements esp with the reduced bondline and together with ease of manufacturing and rework. 1 part Gel and Gap Pads are easily removed and cleaned up esp. during manufacturing and field rework which allow minimum time. However, there will be special cases where other thermal solutions will be required.
Q: How does Henkel (as a vendor) ensure the reliability of the thermal materials to meet the customer requirements?
A: We (in Henkel) performs reliability testing with our thermal materials such as 85C/85RH, Temperature cycling (or Temperature shock), 150 C constant temperature over 1000 hrs to ensure the material characteristics do not degrade. In addition, we also work with customers to perform vibration testing (with their profile) to ensure gap stability over time. We also worked with customers on-site in their qualification testing to ensure the thermal solution meets their needs and expectations.
Q: With regard to Si products, is Si extraction more of a concern today than in past & how are we addressing this perceived issue in new 1k/ 2k TIM development?
A: Yes and no. Silicone migration is still some concern esp. cosmetics in the field. We have improved different processing esp. treatment in raw materials in reducing silicone migration volume and maintaining the low modulus requirements.
Q: Are 5G PCBA designs evolving using contoured HS or typical falt heat spreaders that require very large gaps, thus thick Si-based TIMs that typically have corresponding high extraction values?? Or, are they moving to dedicated HS using thinner BLTs?
A: Depending on customers, the trend in 5G has been going to thinner BLTs in reducing thermal impedance.
Q: Are gap pads the principal method of thermal management for small cells?
A: Yes and no. Both Gap Pads and Liquid solution such as 1 part Gel have been used in the thermal management for small cells.
Q: Shore hardness 75 value is very high, what about the conformability, when different thickness pads are used?
A: The shore hardness is 000 @ 75 … not shore 00. The TGP 7000ULM comes in 40 mil (1 mm) to 125 mil (3.125 mm)
Q: What is meant by ‘tunable modulus’?
A: For a curable Gel (CGEL), we can tune the modulus in the Gel product. For example, a specific customer wants a lower modulus in an existing product, we can quickly modify the formulation and create another product without going through major development.
Q: What does the (1K) and (2K) represent for thermal gel and thermal gap filler?
A: 1K means 1 part liquid (or Thermal Gel as we call it) and 2K means 2 parts liquid (part A and part B) for thermal gap filler where one of the two parts contains the catalyst for curing.
Comment: Modulus- but tuned versions also require a new IDH, if my experience at Henkel holds true- this can be an effort in futility & months process.
A: Yes. IDH will be required. Depending on the business case and approval, sometimes it can be done via MOC for a similar product with a small change.
Q: Does Henkel have any thermal solution for pluggable modules like QSFP/QSFP-DD?
A: Depending on the application. We do not have a solution for TIM 1 (means within the chip itself). I would strongly suggest to touch base with your Henkel contact and see what we can do for you in the QSFP/QSFP-DD for more info. Thanks!
Q: What is the range of target modulus needed for low stress?
A: Depending on the system and customer requirements, I have seen 8psi to 35 psi as the target for low stress.
Q: Advise on 2k materials – the K values are the same for each Part.
A: Typically, the final product is where the K values are reported in the TDS. They should be very similar for each part A and B. However, that will depend on the product itself.