A new investigation suggests that Apple’s recent range of MacBook Pro laptops could be affected by failing chips due to bad materials and thermal stress.

So called Nvidia ‘bad bumps,’ the tiny balls of solder that hold a chip to the green printed circuit board it sits on, will eventually crack, causing major problems for any computer user, and have adversely affected the chip manufacturer in recent months.

Dell and HP were among computer manufacturers who suffered, Nvidia took a $200 million charge over the problem in July.

Apple MacBook Pros were thought to be immune to the problems associated with the Nvidia chip, but research by The Inquirer suggests otherwise.

The Inquirer points out the ‘bumps’ are virtually invisible to the naked eye, about 100 micrometers in diameter, similar to the diameter of a human hair.

To complicate things, they are permanently sandwiched between the chip die and the green fibreglass carrier, the bumps literally solder the two together. They are then covered with an epoxy-like material called underfill.

To discover if the MacBook suffers from ‘bad bumps’ The Inquirer, bought a MacBook Pro off the shelf, disassembled it, desolded the chips, sawed them in half, encased them in lucite, and ran them through a scanning electron microscope equipped with an X-ray microanalysis system.

Investigating the Macbook Pro's bad bumps

A brand new 15-inch Macbook Pro, purchased in California, revealed ‘bad bumps’ according to lab tests by The Inquirer, backed up by detailed screen shots on their website.

The MacBook Pro motherboard was revealed to have three chips on it, the Intel CPU on the bottom, the Nvidia MCP79 chipset, and the Nvidia G96 CPU. The MCP79 is marketed under the name 9400M, and the G96 is called a 9600M GT GPU say The Inquirer.

The bumps have two possibilities, new and old, good and bad respectively. According to Nvidia documentation, the 'bad bumps' consist of mostly lead, 95% lead (Pb) in fact, with the remainder being tin (5% Sn). That is why they are called high-lead bumps. The newer 'good bumps' are called eutectic.

The extensive report includes numerous images and graphs to back up The Inquirer’s claims and a revealing follow up email correspondence between the author and Mike Hara, Vice President of Investor Relations and Communications at Nvidia.

Nvidia has vehemently disagreed with the allegations, calling them "untrue". Michael Hara, vice president, investor relations and communications at Nvidia told CNET The Inquirer's "initial analysis of problems with some of the older chips was already flawed" and that the original problem announced on July 2 was rectified. "When you build a device, it's the material properties and everything in combination that leads to the robustness of the design. What we call the 'material set'" said Hara, "It's a combination of the underfill (a kind of a glue that helps hold the chip down) and the bump together that creates that stability in that connection. A more robust underfill would have taken the stress off the bumps and kept that (original problem) from happening. What we did was, we just simply went to a more robust underfill. Stopped using that (previous) underfill, kept using high-lead bumps, but we changed the underfill. And now we don't see the problem."

Nvidia has also issued a written statement: "The GeForce 9600 GPU in the MacBook Pro does not have bad bumps. The material set (combination of underfill and bump) that is being used is similar to the material set that has been shipped in 100's of millions of chipsets by the world's largest semiconductor company (Intel)."

Click here to read the original article at The Inquirer.

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