A new packaging technique using a film carrier for laser diode arrays

This paper reviews a new packaging technique for laser diode (LD) arrays. This technique uses a new film carrier which has high-density inner leads and fanned-out microstrip line patterns on polyimide film. The film carrier is used to connect the LD array to peripheral circuits, such as LD drivers. There is less mutual inductance between lines on the film carrier than with the conventionally used airing structure which comprises bonding wire and an alumina (Al₂O₃) circuit board. This structure can reduce the electrical crosstalk between channels on the LD array with high-density interconnection. A 4-channel LD array sub-module is fabricated employing the above technique, and demonstrated. The module has good frequency characteristics over a bandwidth of 2.3 GHz. The electrical crosstalk between adjacent LDs is less than -30 dB at 1 GHz. This value is about 10 dB lower than with the conventional wiring structure