There are two kinds of coffee filter. Is either kind lint-free?
This question is not specific to any particular device, unless bits of fabric are devices. I ended up answering it myself in some ad hoc tests of various materials used to clean things, and wondering about a questions raised by my informal research.
In many instructions a lint-free cloth is specified, and the suggestion that a coffee filter can serve as the lint free cloth is included. There are two kinds of coffee filter: one is the flat-bottomed, ruffle-sided, typically white filter that was ubiquitous in the heyday of Mr. Coffee coffee makers. Melitta popularized the cone-shaped filter, a sort of cylinder with a hockey-stick-shaped seam that closes the bottom and makes an oblique-angle turn upwards, extending to the top edge of the filter. They can be white or unbleached. They are very popular in coffee-drinking and electronics-cleaning circles.
My internet search did not cough up any wisdom about or attention to this microprocessor-maintenance life-or-death matter, which might mean both types of filter are suitable for cleaning components. I did see many instances of Melitta-style filters used in tasks that call for lint-free cloth, among which no harm appeared to have been done, but that is not proof that they're lint-free. I found no instances of Mr. Coffee-style filters used for anything at all.
I wetted various aspirants to lint-free status and rubbed them against a tightly woven black cotton fabric. I documented their lintiness under certain conditions in a photograph, which I will happily share if ifixit provides a way to do it.
A Melitta-brand cone style coffee filter shed fibers like a buffalo in springtime.
A Mr. Coffee-style coffee filter released a significant amount of fiber, but was markedly less generous than the Melitta filter.
RATING: Fair to Poor
An old chamois cloth used to dry cars several dozen times gave up a lot of DNA
A new cotton towel did leave lint on the shirt, but it was hard to see.
RATING: Seems okay to me, but don't take my word for it.
A polyester microfiber cleaning cloth held onto its molecules like a dilettante clings to treasured pretensions
My undertaking answered my question and posed a few new ones. Who started the rumor that coffee filters are lint-free? Given that they shed like molting cockatoos, why don't coffee filters have a reputation dropping lint that sets electronics on fire, shorts circuits or otherwise fails and bricks our electronic loved ones, as promised?
What I learned: Neither type of coffee filter can be considered lint-free when wetted in water and rubbed against dry, tightly woven cotton fabric. An old genuine chamois was almost as bad as the Melitta cone filter. A new cotton towel was less prone to shed lint than all but the microfiber cloth. A polyester microfiber cloth won the day, leaving nothing detectable behind.
What to clean your logic board with:
a) probably any absorbent material at hand, since people have been using coffee filters without disastrous consequences since the dawn of DIY computer repair
b) if you don't want to leave lint on your heat sinks and circuitry, a microfiber cloth. A cotton cloth isn't a bad bet, based on my findings. Test yours by wetting it and rubbing against smooth fabric in a contrasting color to determine its likelihood of leaving lint all up in your stuff.
A picture of my lint-testing outcomes, in black-and-white and color, pretty much answered my original question. It also raises new questions.