Visual Inspection
Visual Inspection - The Concept
Due to the delicate nature of the product and the varied stresses endured during
it's fabrication, dicing and arrival to it's finished form, each individual chip
requires a level of visual inspection to remove defective product. Flaws in the
finished product usually originate at either the fabrication stage or are caused
by physical mishandling during the separation process. Although the origins of
each flaw may sound clear-cut, the ability to visual inspect finished product
requires a lot of skill and training which is greatly aided by experience.
Mintech staff have long term experience combined with a high level of investment
in training, enhanced inspection abilities ensure that die can methodically run
through this process with necessary speed and also the required degree of
accuracy. Due to the varied nature of the product and the many different levels
of inspection that can to be performed it is vital to have 100% confidence in
the inspectors ability to identify a flaw in relation to the visual standard
being imposed by the order. For example the same defect may pass to MIL STD 883
Condition B, but fail to MIL STD 883 Condition A.
Visual Inspection - The Process
To perform visual inspection at Mintech the member of staff must be deemed
competent. This competency is only attained after 100 hours intensive training.
All inspectors are graded on their ability to inspect and must prove competency
in their current field in order to progress to inspecting more complex devices.
For example all inspectors begin approved to inspect simple transistors and
diodes, it may actually take years to receive approval to inspect a complex IC.
All product at Mintech receives 2 inspections, the first inspection occurs after
the product is placed in it's end container where rejects are removed and
replaced with acceptable product. The second inspection occurs as a final
quality check, commonly known as final Q.C. This is performed by a senior member
of staff with long term experience in all product types. Achieved by methodical
organisation and by retaining a long-term workforce Mintech maintains a fast
efficient visual inspection route able to meet the demands of new products.
Visual Inspection - Capabilities
- MIL STD 750 - method 2072 for transistors
- MIL
STD 750 - method 2073 for diodes
- MIL STD 883 - method 2010 condition A or B for
Integrated Circuits
- ESA SCC Specifications (1)
- Customer Specifications
Specialised Wafer Inspection
With the increased use of dice ring foil format,
customers need to be able to use hybrid assembly machines which detect only dice
that are both electrically and visually acceptable. Whilst this has been
standard for dice in waffle trays it has not been possible for dice on Ring
Foil. Mintech has developed a unique system for the inspection and inking of
visually imperfect dice whilst on Ring Foil. By the use of special inks we can
ensure that dice detection systems at the hybrid assembly stage only pick up the
good dice.