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shift during transfer molding. However, mechanical components, such as springs. quantify the die positioning and its
this concept does not solve an essential However, by considering glass fibers for accuracy, TGVs were produced in the test
cause of die alignment inaccuracies: the the alignment structures, this perspective dies and the mounting wafer substrates
die placement. changes: for glass fibers without surface to be used as alignment marks (Figure 4
Modified GEFOP by passive die defects, fracture strengths greater than and 5). The metric used for qualification of
alignments. The modified GEFOP 1GPa can be found in the literature [4]. the alignment error of each of the designs
presented here is based on the usage of T he pr i ma r y obje ct ive of t h is shown in Figure 4 was the standard
passive die alignment structures. The investigation was to reduce the alignment deviation of the die position measurements.
spring-like die alignment features are error after die placement. In order to Results. First, the spring elements
placed on two adjacent sides of the open shown in Figure 4 were examined
cavities (Figure 4). When the dies are for their suitability. For this purpose,
placed, the alignment devices spring in a glass substrate was processed with
and precisely align the die in relation
to the mounting substrate. As in the
conventional GEFOP concept, after the
die placement all gaps are filled with the
EMC, which is then cured and processed
like a normal reconstituted wafer.
Methods. T here a re t wo mai n
considerations for modified GEFOP
wafers with passive die alignment
features: 1) Design of such features, and
2) Accuracy measurement of die position.
Both are discussed below.
Glass is prone to brittle fracture Figure 4: Schematic drawings of the GEFOP designs
if not free of surface defects such as tested in this work (in red color). At the bottom left of Figure 5: A SEM micrograph of glass die mounted in
the glass substrate with passive alignment features.
the image (in green color) are alignment marks used
micro-cracks. Therefore, it may not be as reference for the measurement of the cavity and The red arrows indicate the alignment marks used in
normally seen as a structural material for the test die position. the measurement of the die position.

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