A change to a manufacturing process enabled radio frequency screening cans for use on electronic products to be produced quicker and cheaper.

When a customer approached Photofabrication Services for a quote to produce RFI screening cans, the company found that changing the manufacturing process and specifying a RoHS-compliant finish enabled parts to be formed and spot-welding after plating, resulting in a substantial reduction in both cost and lead-time.

Photofabrication Services, a photochemical milling company, has the capability to manufacture virtually any component from sheet metal ranging from 0.05mm to 1.5mm in thickness.

Model to finished part

One class of components where chemical milling is often the preferred method of manufacture is RFI (radio frequency interference) screening cans for use on electronic products.

The majority of screening cans are manufactured from 0.25mm to 0.5mm thick metal, and often bear the name of the customer etched into the surface.

Photofabrication also offers its customers crucial technical advice, such as when a potential customer recently needed a price-sensitive RFI screening can set.

The set comprised three parts, each of which was different in design and form.

One of these parts was to be spot-welded. The base metal was mild steel, which was initially to be hot tin dipped.

However, this type of plating is not compliant with the RoHS (Restriction of the use of certain Hazardous Substances, 2002/95/EC) Directive.

After considerable thought and discussion with the customer, Photofabrication proposed changing the plating from hot tin to dull nickel.

The benefit of this was that the lead-time and cost of plating were reduced by virtue of the way the parts were etched in sheet form – using retaining tabs to hold the matrix of components together – and then dull nickel plated in the form of an etched sheet.

Photofabrication could then form the parts using half-etched fold lines and fly presses. Through its experience with previous projects, Photofabrication has found that dull nickel is the only type of plating for which forming post-plating is successful when using hard tooling.

Spot welding

Finally, there remained the need to spot weld the RFI screening can. Spot welding is usually performed pre-plating, as there is a risk that the protective properties of the plating will be compromised if welding is carried out post-plating.

However, with dull nickel-plated mild steel, the spot welding process creates a nickel-iron alloy that offers improved corrosion resistance compared with mild steel. Because the environmental application was neither hostile nor external, the corrosion protection for the spot welded component was more than adequate.

As a result of the modifications to the component plating specification and manufacturing process, the cost of the RFI screening can set was cut by 31percent and the lead-time was also reduced.

Furthermore, dull nickel offers a much better finish than hot tin, so the parts benefited from a far more attractive appearance.

With the plating specification and manufacturing process proven, the customer was able to place the order with confidence – and was subsequently delighted with the final parts. 

For more information, visit www.photofab.co.uk