What does AQL 0.65 % mean?

AQL stands for Acceptance Quality Limit. The AQL value is used in sampling inspections to decide whether a production batch is accepted or rejected. This is based on sampling plans as described in ISO 2859-1 for attributive inspections, among others. Here, not every single component is inspected, but a defined random sample is taken from a batch and evaluated.

An AQL of 0.65 % means simplified: Within a statistical sampling inspection plan, a certain quality level is accepted at which a limited number of defective parts within the sample can still lead to the acceptance of the entire batch. The actual inspection decision, however, depends on several factors: the lot size, the selected inspection level, the sample size and the permissible number of acceptances and rejections.

It is important to note: AQL 0.65 % does not mean that a lot is free of defects. Nor does it mean that a maximum of exactly 0.65% defective parts are contained in the delivered batch. AQL is a statistical procedure for lot acceptance based on a random sample - not a 100% inspection of every single component.

How is AQL 0.65% applied in practice?

In an AQL inspection, a randomly selected sample is taken from a production batch. This sample is tested. An AQL inspection plan is then used to decide whether the entire batch is accepted or rejected. The sample size is not arbitrary. It usually results from

• the lot size,
• the inspection level,
• the selected AQL value,
• the inspection type,
• and the defined acceptance and rejection limits.

This means that not every part is automatically inspected. With AQL random sample testing, it always remains a random sample test with a residual risk for the customer.

Why is AQL 0.65 % not sufficient for critical electronic components?

In the case of frequency-determining components such as oscillating crystals, SMD oscillating crystals, clock crystals and quartz oscillators, a single faulty component can have a considerable impact on the end product. Possible consequences are, for example

• unstable oscillation of the oscillator circuit,
• unstable clock frequency,
• communication errors,
• increased power consumption,
• shortened battery life,
• field failures,
• complaints,
• service costs,
• or loss of image with the end customer.

Especially in applications such as smart metering, IoT, IIoT, wireless, medical technology, industrial electronics, automotive, sensor technology and safety-relevant electronics, quality is not just a statistical indicator. Quality determines the reliability of the entire end product.

But what exactly does QTL 0.65% mean?

Example: In a delivery batch of 10,000 units, only 200 units are randomly tested according to an AQL 0.65% test plan that is standard in the industry, with normal testing and General Inspection Level II. If up to 3 defective parts are found in this random sample, the entire batch of 10,000 pieces can still be accepted and delivered. The batch is only rejected if there are 4 or more faulty parts in the random sample. However, this does not mean that the customer only has 3 defective parts in the delivery lot of 10,000 pieces? It only means that although 3 defective parts were found in the random sample of 200 pieces, the entire lot can be delivered to the customer. The delivery lot can therefore contain many more defective parts than just the 3 that were found in the random sample. This means that the recipient of the goods has a quality problem. PETERMANN-TECHNIK therefore deliberately goes further: we only deliver products that have been 100% tested in order to not only statistically assess the risk for our customers, but to actively minimise it to our 0 ppm target.

Why are PETERMANN-TECHNIK products 100% tested?

The products supplied by PETERMANN-TECHNIK GmbH go beyond the usual AQL random sample testing in the industry and rely on 100% testing for all oscillating crystals and oscillators. This means that not just a random sample, but every single relevant component is tested before it is delivered to the customer.

Our aim is to reduce the quality risk for our customers to 0 and to consistently anchor the demand for 0-ppm orientated quality in the process. While an AQL inspection statistically assesses whether a batch can be accepted - regardless of the actual defective parts - PETERMANN-TECHNIK's 100% inspection takes a different approach: defects should not be statistically accepted, but systematically recognised and avoided.

For our customers, this means

• greater reliability in series production,
• lower risk of faulty components in the field,
• more stable product performance,
• less risk of complaints,
• better planning capability,
• higher end customer satisfaction,
• and greater technical differentiation from competitors.

Why is PETERMANN-TECHNIK the right partner for 0-ppm-orientated quality?

PETERMANN-TECHNIK GmbH is the right partner for customers who expect not only statistical sample quality, but also maximum process and product reliability for oscillating crystals, SMD oscillating crystals, clock crystals and quartz oscillators. We do not see quality as an afterthought, but as an end-to-end process - from technical advice and the right product selection to 100% testing of the supplied components.

In our view, the industry-standard AQL value of 0.65% is not sufficient and is not enough for electronics applications. The customer does not need a statistically accepted probability of error, but a component that functions reliably in its application. Today ^. Tomorrow ^. at any time and for decades to come!

This is why PETERMANN-TECHNIK relies on tested quality, technical application expertise and 100% testing. In this way, we support our customers in developing safe, durable and high-performance electronic products. Our quality standards are clear: we do not want to manage our customers' risk, but minimise it to a 0 ppm target.

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