Mould insert fabrication of a single-mode fibre connector alignment structure optimized by justified partial metallization

Abstract

In this report, we present a new method for generating a high-density (2D) droplet array using double-layered polydimethylsiloxane (PDMS) templates containing honeycomb microwells. Without external flow control, a dropleton-template (DOT) was created by utilizing capillary forces associated with the interfacial tension between the aqueous and oil phases. The DOT process involved three simple steps: (1) vacuum-assisted filling of microwells; (2) excess water removal; and (3) covering the droplet array with oil. To demonstrate the concept of the DOT, we generated spherical water droplets 147, 191, 238, 326 and 405 μm in diameter from corresponding microwells with lengths of 200, 300, 400, 600 and 800 μm, respectively and a height of 76 μm (up to ~1 0,000 droplets on a template 25 × 25 mm). Two important factors, including the aspect ratio (height-to-length ratio) of the microwell and the interfacial tension of the two phases, were investigated to understand how those factors affect the shape of the droplets ('sphere' or 'dome'). All the droplets were spherical up to an aspect ratio of 0.55. The droplets were dome-shaped for aspect ratios above 0.82. For a 1 mM sodium dodecyl sulfate (SDS) solution, the use of mineral oil (which had the highest interfacial tension studied) produced spherical droplets, but dome-shaped droplets were produced by corn oil and oleic acid.

Design and prototyping of self-centering optical single-mode fiber alignment structures

“…An insertion loss down to 0.1 dB is achievable in case care is taken to control the protrusion of the fiber in the alignment structure and in case index matching gel is applied. In addition, a metal mould was created from the DPW prototypes using electroplating [41] to assess the compatibility of our designed SCAS with the replication technology of hot embossing. This replication is currently ongoing and the reliability of the replicated parts will be characterized.…”

“…The fabrication of a metal mould from a DPW master comp onent was investigated in collaboration with the Karlsruhe Institute of Technology (KIT). Here DPW prototypes were used as sacrificial master components in an electroplating process that forms a nickel negative of the proto type [41]. With the nickel mould insert created successfully, the next step is to replicate the SCAS in high-performance polymers (PEI, PSU) by means of hot embossing [24,28].…”

Replication of self-centering optical fiber alignment structures using hot embossing

“…To avoid these possible errors, we have developed a justified partial metallization process for the mould formation. 18 This process requires the polymer prototype to be attached to a copper substrate. A dip method was used to apply adhesive to the prototype structure, which is subsequently pressed against the copper substrate.…”

“…To ensure that the electroforming starts by filling the small through-holes and only after filling those, covers the rest of the structure, a seed layer is deposited on the structure with physical vapour deposition through a mask. 18 This allows us to avoid defects like void spaces or loose parts in the electroformed nickel mould. The final step of the mould insert fabrication consists of cutting the mould insert to its desired dimensions by wire electron discharge machine cutting.…”

“…unable to remove with laser ablation. 18 This will cause the SCAS replicas' spring cavities (shown in Fig. 2(b)) to not be fully open over the whole depth of the structure, thus increasing the spring-constant (stiffness) and the force required to insert a fiber in the SCAS.…”