Advanced Packaging

Waferlevel-Packaging

Wafer level packaging (WLP) is a highly parallel process for the hermetical housing of micro mechanical and micro optical components. Based on our longtime experience in this field we offer a WLP “off the shelf” concept, from design up to pilot production. A technology transfer to high volume Foundries is an additional option. This concept guarantees the advantages of cost reduction and risk minimization for the customer.
The verification of the inner pressure in a waferlevel package can be a stringent demand to estimate the expectable lifetime of a product. To date, there is no generally usable method for a cheap and sufficiently precise application to all kinds of MEMS. However, for resonant structures, ISIT has developed the "Neon ultra-fine leak test" based on measuring the Q-factor of an electromechanical oscillator (dampening effect of the enclosed gases), which allows to detect extremely small leak rates and to forecast the pressure increase over a product's lifetime. (Semi Guideline 4446 "Evaluating Hermeticity of MEMS Packages").
To maintain a vacuum in a very small package, outgassing and desorption of gas molecules from the inner surfaces has to be controlled. So-called "getter" films allow to absorb free molecules of the most frequently found gas species, like an in-situ pump that remains active through the whole lifetime of a product.