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.

Die Technology 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 Die Technology 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 Die Technology 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 Die Technology 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. Die Technology 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.