OSRAM’s filament looking LED application note. Link here (PDF)
SOLERIQ® L38 (GW T3LxF1) is a filament LED with a beam angle of 360deg for indoor retrofit lighting applications. It combines the advantages of modern LED technology with the aesthetics of traditional light bulbs.
The construction of the SOLERIQ® L38 consists of a ceramic based frame with two alloy connectors at both ends. A number of highly efficient LED chips (depending on the lumen package) is mounted on the ceramic based frame and they are electrically connected through wire bonding, covered by a colored diffused silicone resin.