Story-Headerimage
2 min reading time
Story 141 – 1990 – Products

Why it’s a big deal

Sheet for leadframes must be absolutely fault-free

Microchips use filigree conductor tracks made of copper alloys – the lead frames. The absolutely flawless surface of strips used for this purpose is crucial. Wieland takes a number of measures to ensure that they have the required high quality.

Integrated circuits, usually in the form of microchips, have become indispensable. They are used in PCs, laptops and smartphones as well as in space rockets and large servers - or even in children's toys or fully automatic coffee machines. The supply and discharge of the signal and control currents for the chips are carried out with copper alloy conductor tracks, the lead frames. They are usually punched from strips by the manufacturers, and in the case of particularly filigree lead frames they are also etched.

The challenge lies in the tiny dimensions: Leadframe conductor tracks are often only 50 micrometers, i.e. 0.05 millimeters thin. Later, a so-called bonding wire is applied to them for connection to the chip, which in turn has only half that diameter. This only works if the leadframe - and thus also the original copper alloy strip – has no defects whatsoever. Even the smallest impressions, dirt or dust are not acceptable.

For Wieland, this means that absolute cleanliness on all rolls and rollers must be ensured in the production of these strips. Surprisingly, even mosquitoes are among the disturbing factors: The insects like to cool their trunks on the copper strips – and are then rolled in as well. This is a serious problem which can be successfully counteracted by installing blue light lamps.

In addition, all strips for leadframe production are extensively checked for possible defects. The surface inspection system (OIS) is one of the tools used here. It is installed after each pickling process, runs automatically and inspects the strip on both sides. Faulty spots are automatically detected, electronically marked on a "surface map" and cut out during the last production step, the slitting.

Thanks to the enormous effort in the search for the smallest defects or damage, Wieland ensures that customers in leadframe production only receive strips which reliably meet the extreme quality requirements in this area.

The filigree nature of leadframe tracks requires extremely thin strip without any defects. A complex surface inspection system (OIS) ensures this.