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Precise assembling of VCSEL or laser modules Disclosure Number: IPCOM000239594D
Publication Date: 2014-Nov-18
Document File: 1 page(s) / 30K

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Precise assembling of VCSEL or laser modules

    Today, the common way of assembling high power VCSEL modules consists of the following steps: VCSEL-arrays (in the following also called "chips") are soldered on a submount using Au-Sn solder. Then these submounts are soldered to a heat sink using SAC solder. The heat sink is usually made of a metal (e.g. copper).

    The position accuracy of the VCSEL arrays on the heat sink is influenced by the precision of the different steps. Since these assembly steps are independent of each other, errors add up and lead to an overall alignment accuracy of the VCSEL arrays with respect to the heat sink that may be large (100┬Ám or more).

    The reason for this is that the precision is determined by a long tolerance chain which includes: the precision in the first solder step (AuSn on submount), the positioning of the metallization layers on the top and the bottom of the submount, the positioning accuracy of the solderstop on the heatsink and the accuracy of the 2nd solder step (where mainly SAC is used which shows self-alignment).

    In some applications it is required that the positions of the VCSEL arrays on the heat sink are precisely aligned with respect to each other.

    To achieve this, it is required that the different steps entering the tolerance chain must not be independent on each other, but rather use the same reference feature.

  It is proposed to overcome the above mentioned issues by the following steps:
only one submount or frame...