Insights From Leading Edge



IFTLE 66 3M / IBM Seek to Improve Thermal Underfills; TSMC in Back End Packaging, Again

New thermal underfills for 3D chip stacking

Earlier this week 3M and IBM announced that the two companies "plan to jointly develop the first adhesives that can be used to package semiconductors into densely stacked silicon "towers" [...] which will make it possible to build [...] commercial microprocessors composed of layers of up to 100 separate chips." While giving little technical detail, they announced that this proposed program could "potentially leapfrog today’s current attempts at stacking chips vertically" and offer low power solutions for "makers of tablets and smart phones". IBM was quoted as saying that IBM scientists are "aiming to develop materials that will allow us to package tremendous amounts of computing power into a new form factor — a silicon "skyscraper." The picture that came along with the press release is shown below. It certainly makes it look like the chips are actually being simply glued together, but if this is 3D stacking with TSV then this would be a chips-last solution, and certainly that cannot be done with more than two layers at a time. My assumption was that this was an oversimplification for the non-technical press release.

With the help of 3M and IBM I have made contact with Herve Gindre, division vice president at 3M Electronics Markets Materials Division, and Bernie Meyerson VP of research at IBM, to clarify exactly what is being proposed.

3M’s Gindre indicates that indeed what we are talking about is basically a thermally-enhanced underfill, which he says "will help conduct heat through 3D multichip stacks and/or away from heat-sensitive components circuits." 3M will staff the program in the semiconductor division of its Electronic Market Materials business, which currently provides temporary bonding solutions and CMP consumables to the 3D market place. Gindre points out that 3M will be focusing their "years of commercial experience in composites, nanotechnology, adhesives and thermal interface materials" on the current problem.

IBM will be running the program out of its semiconductor business unit. VP Meyerson declined to share much detail on timing or technology, which is to be expected since the program hasn’t even started. In terms of thermal performance specifications Meyerson offered that "we clearly wish to exceed current thermally conductive adhesive specifications to the point where the newly developed adhesive solutions at worst match those of silicon."

IFTLE will be following any further developments in this interesting program.

TSMC continues to scope out high-end IC packaging opportunities

Digitimes reports that TSMC has undertaken in-house high-end packaging of ICs, produced by its foundry processes, for fabless IC design houses in the US and Europe [link]. This would obviously create competition for Amkor, ASE, SPIL, STATs and other subcontractors.

At the last several TSMC spring Technology Symposia, in Silicon Valley, TSMC announced plans to expand its efforts in IC packaging. [see PFTLE 30, "Foundry TSV are comin’ -- TSMC makes their play for a biggerportion of the pie"] They have been doing wafer bumping, wafer sort, and wafer-level chip-scale packaging on a limited scale for years. At present, the company has two wafer bumping facilities, located in Hsinchu and Tainan. They are expanding their bumping and wafer-level chip-scale packaging technology and have announced copper pillar bump technology on 100μ bump pitch and will be manufacturing silicon interposers with TSV for 3D stacking. TSMC has announced that it is developing the interposers for Xilinx next-generation FPGAs and is in fact bumping them in-house rather than having that done at one of Taiwan’s OSATS [see IFTLE 23, Xilinx 28nm Multidie PPGAâ??¦" and IFTLE 43, "IMAPS Device Pkging Highights: 3D IC"].

According to that Digitimes report, "fabless IC design houses are willing to have TSMC responsible for front-end foundry and back-end packaging services although TSMC’s packaging ASPs are higher than those of IC packaging/testing service providers." They conclude that this is because these fabless IC design houses like the convenience of a one-stop solution and worry about lower yield rates due to outsourced packaging. However, their sources add that "interestingly, so far, no Taiwan-based IC design houses have accepted TSMC’s higher quotes for packaging services."

Indications are that TSMC can generate gross margins of 50-60% for foundry services but even with their higher prices only 20-30% for packaging services. Thus some are questioning why they would expend precious equipment capex on the packaging side.

Whatever your take is on this new information, it is clear that TSMC is slowly but surely moving into what was before a clearly defined packaging and assembly space.

Update on Lester Lightbulb and the LED space

Several of you have tried to leave comments on IFTLE 63, "Bidding Adieu to Lester Lightbulb" and one of you was actually peeved enough that you couldn’t, that you contacted our editor Jim Montgomery. Thanks for that, because it exposed a flaw in the new software that appears to be blocking comments. Jim says they are working on it. One issue appears to be my reported price for the EnduraLED 60W equivalent. One reader claims he has found them for $39 and even $19. Jim got interested in this and tells me that he can now find them for both prices in different parts of the country. All I can tell you is that the Home Depot price on the day the blog was written was $47. The one that I now have installed actually cost me $49.99 since I bought it locally (and still have the receipt). Anyway, my point is not that the price would never come down, but rather how far down it had to come to make purchase of this device a good business decision vs the CFLs. Both bulbs are still glowing brightly — as well they should, well past my lifetime expectancy if I am to take their marketing propaganda seriously.

Two other readers sent me email indicating that my concern over the life expectancy of the components in the bulb were well-placed, and that this certainly was not taken into account by Philips in their lifetime claims. I guess only Philips can answer that question.

For all the latest on 3D IC and advanced packaging stay linked to IFTLEâ??¦â??¦â??¦â??¦â??¦â??¦â??¦â??¦â??¦â??¦â??¦â??¦â??¦â??¦..

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