PCB manufacturer Leicester UK
printed circuit boards Leicester
item2a
6
pcb burr removal

Subject:
Further innovative engineering has led Leicester Circuits LTD to develop a unique chemical process step to enable the production of burr free Plated Half-Holes for use as component smd pads.

Situation:
Many component manufacturers are now utilising organic substrates for circuitry contained within component housings e.g. Oscillators and DC-DC Converters. These products make use of the holes at the edge of the pcb to make contact with the motherboard and effectively create a surface mount pad from a Plated Half-Hole.

Problem:
During manufacture it is necessary to rout through the middle of the plated through barrel of the hole leaving no excess copper either as a burr or a plug in the remaining half-hole. This operation is very difficult to complete without some residue using normal production methods.

Solution:
Leicester Circuits LTD fully evaluated the use of mechanical methods for profiling/routing the half-hole and it was found that standard routing methods always resulted in the copper wall on the back side of the hole (rout entry) pulling from the laminate, resulting in a copper burr. Various cutters were evaluated using a range of speeds/feeds and backing and entry boards but the result was always the same. Routing from the centre of each hole was tried and found to offer a partial solution but increased processing time meant that this was not a viable option.
It was determined that this would be better achieved with the introduction of an additional chemical process step. This new process flow route was fully investigated, trialed and evaluated resulting in significantly improved yields. This process change is company confidential but has led to a significant improvement in quality and has eradicated the burring issue.

Evaluation:
Large numbers of circuits have now been produced using this method of production and new customers have been won on the back of this innovative process step. Leicester Circuits LTD have now begun to evaluate the production of product requiring smaller Plated Half-Holes and will continue to develop this process further. This revised process flow is now available to all customers and our engineering department will ensure that all products with this feature will be subjected to this new process route

Approvals

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LEICESTER CIRCUITS LTD
48 Boston Road
Gorse Hill Industrial Estate
LEICESTER LE4 1AA
UK

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