a b s t r a c tElectroplated tin finishes are widely used in the electronics industry due to their excellent solderability, electrical conductivity and corrosion resistance. However, the spontaneous growth of tin whiskers during service can result in localised electrical shorting or other harmful effects. Until recently, the growth of tin whiskers was successfully mitigated by alloying the tin with lead. However, restriction in the use of lead in electronics as a result of EU legislation (RoHS) has led to renewed interest in finding a successful alternative mitigation strategy.Whisker formation has been investigated for a bright tin electrodeposit to determine whether whisker growth can, at least partially, be mitigated by control of electroplating parameters such as deposition current density and deposit thickness. The influence of substrate material and storage at 55°C/85% humidity on whisker growth have also been investigated.Whisker growth studies indicate that deposition parameters have a significant effect on both whisker density and whisker morphology. As deposition current density is increased there is a reduction in whisker density and a transition towards the formation of large eruptions rather than potentially more harmful filament whiskers. Increasing the tin coating thickness also results in a reduction in whisker density. Results demonstrate that whisker growth is most prolific from tin deposits on brass, whilst that from tin deposits on rolled silver is greater than that observed for tin deposits on copper.

PurposeMicrofluidic or “lab‐on‐a‐chip” technology is seen as a key enabler in the rapidly expanding market for medical point‐of‐care and other kinds of portable diagnostic device. The purpose of this paper is to discuss two proposed packaging processes for large‐scale manufacture of microfluidic systems.Design/methodology/approachIn the first packaging process, polymer overmoulding of a microfluidic chip is used to form a fluidic manifold integrated with the device in a single step. The anticipated advantages of the proposed method of packaging are ease of assembly and low part count. The second process involves the use of low‐frequency induction heating (LFIH) for the sealing of polymer microfluidics. The method requires no chamber, and provides fast and selective heating to the interface to be joined.FindingsInitial work with glass microfluidics demonstrates feasibility for overmoulding through two separate sealing principles. One uses the overmould as a physical support structure and providing sealing using a compliant ferrule. The other relies on adhesion between the material of the overmould and the microfluidic device to provide a seal. As regards LFIH work on selection and structuring of susceptor materials is reported, together with analysis of the dimensions of the heat‐affected zone. Acrylic plates are joined using a thin (<10 μm) nickel susceptor providing a fluid seal that withstands a pressure of 590 kPa.Originality/valueMicrofluidic chips have until now been produced in relatively small numbers. To scale‐up from laboratory systems to the production volumes required for mass markets, packaging methods need to be adapted to mass manufacture.

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