Cytech Systems Lab Case Details EVI: The First Line of Defense for Quality Control

March 22, 2023

According to data analysis, the risk of manufacturers purchasing counterfeit components, expired components, mixed batch components, improperly handled components, recycled components and defective components in the free market has increased from the previous 0.5—1.5% to 5—10%.
Therefore, various testing methods have become indispensable quality monitoring methods to ensure the safety of the supply chain. This is also the original intention of the establishment of the“Cytech Systems Lab" column. On the one hand, it helps customers warn of risks and protects the safety of their supply chains; on the other hand, it also conveys accumulated experience to the entire industry.
The high-standard quality laboratory upgraded by Cytech Systems not only has decapsulation , but also covers basic testing such as EVI (External Visual Inspection) and X-ray Inspection.
So, let’s take a deeper look at EVI.

What is EVI?
EVI, the full name is External Visual Inspection, refers to confirmation of the number of chips received, inner packaging, humidity indication, desiccant requirements and appropriate outer packaging. Secondly, the appearance of a single chip is inspected, which mainly includes: chip type, year, country of origin, whether it has been re-coated, the state of the pins, whether there are traces of re-polishing, unknown residues, the location of the manufacturer's logo, etc.
EVI is mainly based on testing standards to determine whether the chip is brand new, refurbished, and whether the pins are tinned or oxidized. Since the microscopic geometric morphology of the material surface largely affects many of its technical properties and usage functions, observing the surface morphology of the material provides convenience for studying the morphological structure of the sample, helps monitor product quality, and improves product workmanship. 
Generally speaking, both users and manufacturers attach great importance to the appearance defects of products, especially for industries such as electronics, precision hardware, printing, and plastics. Therefore, EVI has become a very important part of quality control.

What does EVI include?
Check that the model, specification, manufacturer, and origin of the components must comply with the design requirements, and the outer packaging must be intact;
The contents of package inspection include: scratches, stains, damage, underfill, spillage, etc.;
The contents of printing inspection include: typos, offsets, missing prints, multiple prints, blur, tilt, displacement, hyphenation, double-layer printing, no font, etc.;
The contents of pin detection include: missing pins, damaged pins, pin spacing, pin width, pin curvature, pin span, pin length difference, pin standing height, pin coplanarity, pin tilt etc.

Why is EVI the first line of defense for quality control?
Components will have obvious characteristics during the production process, and these characteristics can be used as "fingerprints" to identify the authenticity of components. For example, recycled components may have their original information overwritten and reprinted, and often these components will leave evidence on the outside. According to relevant testing standards, EVI can determine whether the chip is brand new, refurbished, whether the pins are tinned, oxidized, etc. Generally speaking, common counterfeit component types will leave visible evidence on the outside.

Cytech Systems Lab Case

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Cytech Systems Shenzhen Laboratory

There are 3 typical EVI cases.

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Case 1: The pin of an ADI sample changes color
Sample model: LT1374CR#TRPBF
Sample testing instructions: The self-inspection defective rate is 100%. The solder ends are yellowed. The yellowed areas and shape are irregular. This may be caused by oxidation or discoloration caused by the plating solution not being cleaned.

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Case 2: The printed information on the label of a certain ST sample is inconsistent with the actual product
Sample model: SEA05TR
Sample testing instructions: The label shows that the printing is SEA05, and the material printing is SEA5. The information on the label is inconsistent with the actual product, and this batch of materials is judged to be a high-risk material.

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Case 3: An NXP sample has skewed pins and exposed copper
Sample model: MC33GD3100EKR2
Sample testing instructions: The self-inspection defective rate is 100%, and there are no scratches in the exposed copper area, so the exposed copper is caused by the electroplating process. The skewed positions of the pins are irregular and the degree of skew at different positions is inconsistent. This is most likely caused by improper material handling.

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