Advanced packaging at the back-end semiconductor manufacturing characterizes various equipment capabilities per device requirement. High resolution imaging for inspection system during die attach process has gained its interest to feature automated selections during in-line processing. Increasing yet stringent requisites of today’s applications give us leading indicators of market’s demand at more functionality in a smaller and complex package. In light with the technology trend, vision inspection system is a well-known challenge. Instead of using a high magnification microscope off-line after assembly processing, leadframe inspection feature uses optical image-based system to recognize real-time feedback on lead-related defects. Such leadframe inspection activation provides good accuracy, monitoring process integrity in real-time for quad-flat no-leads (QFN) leadframe packages. This paper presents how leadframe inspection at die attach machine takes advantage of simultaneous detection of early die attach defect manifestations.

Technological change has brought the global market into broad industrialization and modernization. One major application in the semiconductor industry demands safety and high reliability with strict compliance requirement. This technical paper focuses on the package design solution of quad-flat no leads (QFN) to mitigate the leadframe bouncing and its consequent effect of lifted wire and/or non-stick on leads (NSOL) defects on multi-wire ground connection. Multi-wire on single lead ground (or simply Gnd) connection plays critical attribute in the test coverage risk assessment. Cases of missing wire and/or NSOL on the multi-wire Gnd connection cannot be detected at test resulting to Bin1 (good) instead of Bin5 (open) failure. To ease the failure modes mechanism, a new design of QFN leadframe package with lead-to-diepad bridge-type connection was conceptualized for device with extended leads and with multiple Gnd wires connection. The augmented design would provide better stability than the existing leadframe configurations during wirebonding. Ultimately, the design would help eliminate potential escapees at test of lifted Gnd wire not detected.

Parameter optimization is not only the key to find the most favorable and best solution as variable chances of failure modes may happen at extreme case conditions at unexpected period. Packaging design robustness is much resilient to establish a satisfactorily good quality product and sustain a long-term goal of a remarkable process capability. This paper presents leadframe            design solution of quad-flat no leads (QFN) to address mold flash defect caused by leadframe bouncing during wirebonding. An inverted pyramid configuration was conceptualized to              provide better stability than the standard configuration during wirebonding process and other concerned assembly processes due to the shift of the center of gravity moving closer to the full metal part.

This paper presents the reformation and fabrication resolved on the wire clamp and top plate (WCTP) design to eliminate the presence of lead finger bouncing resulting to high rejection of non-stick on leads (NSOL). Problem experienced was that the hollow or half-etched portion of the leadframe at the top and bottom units caused its bouncing effect. With the aim to improve localized massive NSOL defect, WCTP has been modified to provide positive bias to support its hollow part or the half-etched part of the leadframe at the top and bottom of the units. The re-designed WCTP was fabricated, extending its clamping with enhanced vacuum on top and bottom rows. The implementation of the improved WCTP design reduced the defect with 88 % improvement with the defect reduction during the lot runs.

Strips that have undergone tape saw singulation will not be completed without the ultraviolet (UV) curing process. To detach the units from the tape, the singulated strips have required further assistance to be loaded for UV cure. Otherwise, hard-to-pick units will be the outcome and sticky residues were usually observed to be attached on the units. Since tape sawn strips requires UV cure, suppliers were asked to engage on upgrading their machine to equip the singulation machine with UV cure. The principle is that after sawing, the singulated strips will be washed and dry normally at the spinner. Then instead of unloading the singulated strips, the machine will pass it first to the inline UV cure machine and then unload when successfully completed the whole process. Through adding the UV curing process in the package singulation sequence, singulated strips unloaded are now ready for the next succeeding process. That way, it would be much help to lessen the handling of sawn strips from one machine to another. The introduction of inline UV cure has simplified the process by automation which increased the security of the units’ quality as well as the productivity of manpower.