John, your chances are not good

By Charles Miller

Modern hard disks are miracles of engineering, but honestly; there are times I believe the miracle is that they work at all. As is the case with other mechanical devices, hard drives do have a finite life. When a new automobile rolls off the assembly line it begins a journey that will ultimately end the day that car is worn out and consigned to the junkyard. The situation is exactly the same with hard drives; every single one of them begins to deteriorate and wear out starting the day it is put in use.

Hard disk failures are now becoming much more commonplace than in the past and one of the reasons I see for this is that manufacturers of hard disks have been mandated to stop using lead in the manufacturing process. Getting lead out of our environment is a good thing, but adding just a tiny bit of lead to the tin used in printed circuit boards was what retarded an exotic form of corrosion. Without lead and exposed to electromagnetic action, tin used in circuit boards forms microscopic “tin whiskers” and when these tiny metallic threads break off inside a hard disk they can cause the disk to fail prematurely.

So far the manufacturers have been stymied in coming up with a solution to this conundrum: Unless they leave the lead in the manufacturing process for hard drives they will die prematurely, but unless we get the lead out of our environment they say we are all going to die. Without the ability to use lead in the manufacturing process, many hard disks eventually contaminate their own sterile environment inside the drive where any contaminants at all can crash the disk.

My friend John asked me why he could not just open his failed hard drive to clean out the contaminants. It is difficult to find the right analogy to describe how clean the environment inside a hard disk has to be. Compared to the inside of a hard drive the most sterile hospital operating room is utterly filthy. Any particle of dust over half of a micron is big enough to do damage to a drive, but how many people really understand the size of a micron? (A human hair is about 100 microns thick.)

Try to imagine the following diagram. There are three circles, one is the size of a large beach ball, next to it is a smaller one the size of a baseball, and next to that an even smaller one the size of a grape. Now visualize the space under a door, just enough of a crack to be able to slip through an envelope, so long as it did not contain more than one or two sheets of paper. The biggest circle, the beach ball, represents a magnified view of a human hair relative to the other circles. The baseball circle represents the relative size of a particle of dust, and the grape-size circle is the size of a particle of cigarette smoke. The letter under the door represents how little space there is between the read/write heads in a hard disk and the magnetic surface of the disk. There is only enough room for a few molecules of air to pass between the magnetic heads and the disk surface, so when some foreign matter as big as a particle of smoke gets inside the disk the result is similar to grinding a pebble in the track of a sliding glass door. Inside a hard disk any foreign matter such as a molecule of perfume can cause a catastrophic failure.

Back to my friend’s question about could he fix his own failed hard drive: Even when it is considered clean, the air we breathe can be full of pollen, plant spores, mold, smoke, skin flakes, bacteria and other airborne particulates. Outside of the factory or a Class 100 clean room it is just impossible to open a hard disk for service without introducing hundreds or thousands more damaging contaminants. John, your chances are not good.

Charles Miller is a freelance computer consultant, a frequent visitor to San Miguel since 1981 and now practically a full-time resident. He may be contacted at 044-415-101-8528 or email FAQ8 (at)


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