Cleanliness in screw-based assembly


The elimination of tiny particles while fastening screws during component assembly is a new feature of quality as even particles, measuring just 100µm can cause a malfunction. The screwdriving assembly process can produce hazardous particles through friction or abrasion. Vacuum sources are recommended at every point where abrasion or friction can occur

Specks of metal contamination can cause serious damage to miniature circuit boards

As miniaturisation of components has progressed, the damage potential of small particles of contamination has grown with equal significance. For Deprag, a specialist in the field of screw fastening assembly, technical cleanliness for such components has become a key requirement.

In miniaturised technology, the elimination of tiny particles while fastening screws during component assembly is a new feature of quality. If, when a circuit board is being assembled, a microscopic piece of steel – invisible to the naked eye – escapes, a disaster is sure to happen. A short-circuit will occur if the tiny fragment accidentally connects two of the conducting tracks.

As assembly parts become ever smaller even microscopic particles, measuring a mere 500, 200, or just 100µm, can cause a malfunction. Which is why what has become known in joining technology as “technical cleanliness” is of increasing importance in the design and building of screw fastening assembly systems.

The technical requirements are becoming stricter, according to Jürgen Hierold, sales manager, for Deprag Schulz, a specialist in screwdriving technology and plant engineering based in Amberg, Germany. As early as the 1980s, Deprag was successfully tackling this problem. The machine tool builder was supplying renowned US manufacturers with screwdriving systems for diskette drive assembly units. “Assembly conditions corresponded more or less to sterile room requirements,” recalls Hierold. “That was a challenge for us as machine tool makers.”

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