Part 7: Metrology for Molding of 3D Chip Stacks

Series: Advanced Packaging - Multi-Sensor Metrology for Every Process Step

A standard method for encapsulating electronic components is molding, in which wire-bonded, soldered or glued microelectronic structures are protected with a thermomechanically tailored, robust encapsulation material. Using mold processes, microelectronic modules can be produced with very high reliability even under extreme operating conditions.

In molding, there are two different processes: transfer molding and compression molding. In both processes, SiO2-filled epoxy resins are used for encapsulation. Transfer molding is a standard technology for high volume production of highly reliable packages. This technology can be used for both leadframe and PCB-based applications. Compression molding is a novel alternative process to transfer molding. Thanks to the short flow distances, it is possible to encapsulate molding on a larger surface area than transfer molding. Therefore, this process is particularly suitable for the large-area embedding of ICs and is preferably used for the production of reconfigured wafers. In combination with suitable re-wiring technologies, compression molds can be used to produce highly integrated single and multi-chip packages in wafer or panel geometry.

After the encapsulated chips have been released from the carrier, solder bumps are mounted on the rear contact surfaces in a following process.

FRT's multi-sensor tools combine various measurement methods and sensors to measure a wide range of surface properties such as 3D topography, flatness, roughness and thickness of encapsulated chips, as well as warpage and deformation under thermal load with high precision. Another application is the measurement of defects after the molding process. Defects are, for example, dimples and voids in the mold which can occur during the encapsulation process.

Due to the multi-sensor concept we follow, the 3D surface measuring tools of the established MicroProf® series can be equipped with point and area sensors for topography measurement as well as with layer thickness sensors. A combination of different measuring tasks in one measuring tool is therefore possible with ease. We are convinced that modern measuring tools must be flexible, retrofittable and future-oriented. For this reason, we have developed the FRT multi-sensor concept, which enables us to adapt your measuring tool to the changes in your demands. Imagine the advantages of a measuring tool that combines several measuring technologies such as confocal microscopy, chromatic methods and atomic force microscopy in a single uncomplicated workflow. With its experience in measurement technology, FRT offers solutions for your special Advanced Packaging applications.

By adding the thermo unit to the MicroProf®, you can measure the surface topography of encapsulated chips under controlled thermal load. This is essential because changes in the microelectronic components due to thermal load can lead to functional failures or even breakdowns. Both fully automatic measurements of the surface topography at different temperatures and dwell times at constant temperatures are fully adjustable.

Whether laboratory, development, quality assurance or production - FRT offers the suitable measurement technology for your application from Advanced Packaging. Do not hesitate to contact us if you have any questions. Our experts will be glad to help you solve your measurement tasks by creating the best possible system configuration for you.


Interested in latest posts of this series? Click below.

Part 1/8: Metrology for Semiconductor Lithography

Part 2/8: Metrology for TSV Fabrication

Part 3/8: Metrology for RDL, UBM and Solder Bump Fabrication        

Part 4/8: Metrology for Carrier Bonding/ Debonding, Backside Thinning and Nail Reveal

Part 5/8: Metrology for Wafer Dicing

Part 6/8: Metrology for 3D Chip Stacking

Part8/8: Metrology for Every Process Step in Advanced Packaging

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