Two teardown experts offer an explanation of the function of thermal paste-an excess of which, in part, prompted iFixit to suggest Apple may have a quality-control issue.
performed a teardown of a new Apple MacBook Pro
Feb. 25, a
day after Apple released the new line
Intel's second-generation Core "Sandy Bridge" processors and Advanced Micro
Devices Radeon graphics chips-the team was surprised to find details that
raised questions about quality.
that has us a little concerned about the new models is their quality control,"
iFixit wrote on its site. "A stripped screw near the subwoofer enclosure and an
unlocked ZIF socket for the IR sensor should not be things found inside a
completely unmolested computer with an $1,800 base price."
The team also
came across considerable amounts of thermal paste, prompting a "Holy thermal
paste!" comment and the suggestion that only time will tell if "the gobs of
thermal paste applied to the CPU and GPU will cause overheating down the road."
teardown images, it looks as though toothpaste had been liberally applied to some
of the machine's more high-tech bits. What exactly is this stuff?
is used for conducting heat from the processor to the heat sink," Miroslav
Djuric, iFixit's director of technical communication, told eWEEK via e-mail.
"The processor needs to have the best connection possible to the heat sink, but
microscopic pockets of air-caused by very slight manufacturing differences
between chips and heat sinks-prevent that connection [from being] effective
(air is an insulator)."
citing Wikipedia, that aluminum, a common ingredient in thermal paste, is 8,000
times more efficient than air at conducting heat.
service manager at Rapid Repair, another company that often performs teardowns,
also helped fill in the picture.
"A fine layer
of thermal paste enables high-powered processors in your computer to quickly
and evenly offload their waste heat by filling the tiny imperfections where
your processor and heat sink meet," Vronko told eWEEK in an e-mail. "Like a
thin layer of glue between interlocking puzzle pieces, their thermal connection
is greatly enhanced by proper application. Just like puzzle pieces though,
too much thermal paste acts as a buffer pushing the processor and heat sink
apart and making for a sloppy ineffective connection."
Checking out the iFixit images
, Vronko agreed that there
appears to be too much paste applied to the CPU and GPU, which might, taken
with the stripped screw, imply that "the quality control processes ensuring
uniformly correct procedures during assembly may need some review."
In the short term,
it's not likely to cause any failures. However, "reduced efficiency in the
cooling system typically causes the fans to run more often and at higher
speeds, increasing noise and power consumption," Vronko explained. "It could
also block the processors from achieving their maximum performance, slowing its
use in demanding applications, and can waste battery power. Improper cooling
can also be hard to diagnose in typical usage, as its effects may appear as
random underperformance or quirks with video performance."
and Djuric noted, however, that this is just a single instance; only one
notebook was taken apart.
worth noting that the cooling efficiency and design in Apple's notebooks are
typically among the best, and a well-designed cooling system could essentially
suffer a minor fault without noticeable impact to the user," said Vronko.
that he couldn't recall ever seeing that much thermal paste in an Apple product
before, and that "like everything else in life, the manufacturing process for
electronics is not perfect."
Noting that he
has a background in manufacturing engineering-which perhaps makes him more
sympathetic than the average consumer to the challenges of manufacturing-Djuric
pointed eWEEK to a graphic of a project triangle: a triangle with "good" at its
top and "fast" and "cheap" at each bottom corner.
like all other design/manufacturing companies, strives for the center of that
graph," said iFixit's Djuric. "But the center is near-impossible to achieve."
respond to a request for comment.