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Frequently Asked Questions (FAQ)

Indigo: Thermal Performance

Q: What is the bond line thickness (BLT)?
Q: Does the die need preparation, e.g. chip metallization or polishing?
Q: How does Indigo compare to the new solders?
Q: How does Indigo compare to greases?
Q: What thermal specs do you have, and how may we obtain them?
Q: Can you package one of our lids or thermal test vehicles (TTVs) with Indigo so we can test the thermal performance?
Q: Chips are getting hotter. Will Indigo be more valuable in the future?
 

Indigo: Other Technical Questions

Q: When fully solid, is it "tacky" at room temperature?
Q: What is the melting point?
Q: Since Indigo is a metallic liquid at operating temperature, are there electrical shorting concerns?
Q: How is Indigo so compatible for a wide range of CTE's? What's the CTE of Indigo?
Q: Most PCMA's have reliability problems with pump-out, drip-out, shake-out, corrosion, and the formation of intermetallic compounds. How does Indigo prevent or avoid all of this?
Q: How may we obtain reliability data?
Q: Are there, or will there be, organics in Indigo?
Q: Is Indigo lead-free and otherwise compliant with the ROHS Directive?
Q: Does Indigo require bonding to a copper lid, or will it work with AlSiC?
Q: I seem to recall the product being available in sheet form. Is it also available in a paste?
Q: How may we obtain an installation guide?
Q: How may we obtain samples of Indigo?
 

Polara

Q: What is the difficulty of incorporating Polara into my product?
Q: What does Polara cost?
Q: Polara and Indigo both cost more than copper lids and a good particle-filled grease. How do they save money?
Q: How much power consumption does Polara take to pump heat?
Q: The wireless communication industry continues to grow. Do you have any solutions for heat concerns in wireless devices, as they become more compact and more data-intensive?
 
Q: What is the bond line thickness (BLT)?
A: The bond line thickness is customizable to the needs of the customer, including any sizes and finishes involved.
 
Q: Does the die need preparation, e.g. chip metallization or polishing?
A: Simply a bare die is preferable for our system, since the PCMA can wet the silicon directly. Also, no special polishing is required. The more flat and polished the surfaces are, however, the thinner the BLT can be made. With any interfacial heat transfer situation, a smooth flat surface will enhance performance, but not in excess of that which is typical of Indigo.
 
Q: How does Indigo compare to the new solders?
A: Soldering is a viable alternative for materials with relatively close CTEs. Indium-based solders have been used for attaching integrated heat spreader lids to silicon dies. This is possible because such solders are highly compliant and mitigate the mechanical stress that would otherwise cause damage to the die or the bond during thermal cycling. Obtaining this compliance, however, requires a BLT of 7-10mil or higher; the quantity of indium required for such a thickness results in significant cost.
 
Q: How does Indigo compare to greases?
A: Indigo provides dramatically superior performance. Click here for details
 
Q: What thermal specs do you have, and how may we obtain them?
A: The data sheet provides specifications and environmental test data.
 
Q: Can you package one of our lids or thermal test vehicles (TTVs) with Indigo so we can test the thermal performance?
A: Absolutely, yes. This is the best way for our customers to get a really clear picture of why Indigo is a winner versus other choices.
 
Q: Chips are getting hotter. Will Indigo be more valuable in the future?
A: Increasingly higher-wattage and hotter applications will indeed benefit greatly from Indigo's higher performance. The higher the wattage, the greater the temperature drop. Its performance also provides more design flexibility for future thermal solutions.
 
Q: When fully solid, is it "tacky" at room temperature?
A: When in solid phase, the material is not tacky but quite solid, similar to solidified solder.
 
Q: What is the melting point?
A: Although Indigo fully reflows at 60•C, a minimum of 70°C is recommended for complete reflow
 
Q: Since Indigo is a metallic liquid at operating temperature, are there electrical shorting concerns?
A: There are no reasonable shorting concerns: Indigo's PCMA material does not migrate out of the joint, even when subjected to significant shock or vibration.
 
Q: How is Indigo so compatible for a wide range of CTE's? What's the CTE of Indigo?
A: Because the Indigo liquidus is at 60•C, it can serve as a high-performance TIM between materials of different thermal expansion characteristics. There is no metallurgical bond, but rather a compliant liquid, so mechanical stress is not transmitted between materials as could with a soldered joint. The CTE of Indigo in its solid form has not been measured since it is liquid at operating temperature.
 
Q: Most PCMA's have reliability problems with pump-out, drip-out, shake-out, corrosion, and the formation of intermetallic compounds. How does Indigo prevent or avoid all of this?
A: Indigo is the result of years of innovative research and thorough testing, and represents a true breakthrough in long-term PCMA TIM reliability. Indigo uses several pioneering approaches and techniques, some patented, and some proprietary, to address all known problems of migration, oxidation, and corrosion.
 
Q: How may we obtain reliability data?
A: The data sheet details the current environmental testing results.
 
Q: Are there, or will there be, organics in Indigo?
A: Indigo provides an all-metal heat path for outstanding performance compared to organic materials. Pressure sensitive adhesives are located near the perimeter of the thermal interface.
 
Q: Is Indigo lead-free and otherwise compliant with the ROHS Directive?
A: Yes, Indigo is lead-free and fully compliant with the Restriction on Hazardous Substances.
 
Q: Do you plan to offer lid + TIM together?
A: Indigo is available as a preform; however there is manufacturing interest in creating a combination of Indigo and heat spreader lid. Contact us for details.
 
Q: Does Indigo require bonding to a copper lid, or will it work with AlSiC?
A: You can use AlSiC. One of the benefits of a compliant interface like Indigo, though, is that non-CTE matched materials like copper may be used for higher performance.
 
Q: I seem to recall the product being available in sheet form. Is it also available in a paste?
A: Indigo is solid at ambient temperatures to facilitate transport, handling, and assembly. Consequently, there is no paste form; additionally, the need for mitigation components requires a preform or foil deployment.
 
Q: How may we obtain an installation guide?
A: This document is available here.
 
Q: How may we obtain samples of Indigo?
A: At present, Indigo is available for the Intel Core 2 form factor.

Indigo also may be fabricated to the specific application and customer requirements (NRE charges may apply).

Contact us
for details.
 
Q: What is the difficulty of incorporating Polara into my product?
A: Very little, as Polara is built and deployed using standard manufacturing and assembly processes. Integration may be discrete, package-level, or die-level as needed.
 
Q: What does Polara cost?
A: The cost depends on the specific customer requirements; in volume applications Polara costs less than a dollar per square inch.
 
Q: Polara and Indigo both cost more than copper lids and a good particle-filled grease. How do they save money?
A: Both Polara and Indigo deliver higher performance than a simple copper lid with a grease TIM. Compared to other products of comparable performance, Enerdyne Solutions technology costs less. Overall thermal solution cost is significantly lower with Polara or Indigo due to their high performance, allowing typical cost reductions in the heat sink, fan, or other elements of the back-end thermal solution of several dollars.
 
Q: How much power consumption does Polara take to pump heat?
A: Although it depends on the application, for a die it would take about 5-10% of the power used for the chip. Polara's efficiency, one should note, enables it to pump much more heat than it generates on its own, resulting in excellent performance and control of hotspots.
 
Q: The wireless communication industry continues to grow. Do you have any solutions for heat concerns in wireless devices, as they become more compact and more data-intensive?
A: Yes. In conjunction with Washington State University, we have built prototypes for Gallium Arsenide (GaAs) technology that proves application of Polara to GaAs RF amplifiers can double thermal performance, reducing junction temperatures by 30•C.[i] To provide for acceptable lifetimes, small form factors, correct operation, and potential for increased power, an effective cooling solution becomes increasingly necessary in wireless applications.

[i] George La Rue, Mohamed Osman, Deuk Heo, Chris Macris, "Ultra-High T hermal Performance GaAs RF Amplifier: Final Report" (July 2005).

 

 

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