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The Importance of Incoming Quality Control of PCB Components

April 4, 2016

 by Renaud Anjoran

Warning about static sensitive device

In an earlier article we emphasized the importance of production planning for PCB manufacturing. Another critical success factor is controlling components before PCB assembly (incoming quality control) and segregating bad components.

Identifying defective components as early as possible

The quality of the final product directly depends upon the quality of the components that go into it; therefore, it is essential that all parts are inspected before they are used in any final assembly. A procedure for inspecting all incoming components and parts is necessary as this is the stage where any faulty parts delivered by the supplier should be identified and put to one side and quarantined, thus preventing them from entering the store's stock.

Over an extended period of time, we have witnessed Chinese companies’ take a relaxed approach to their incoming inspection processes which has impacted the quality of products made. Consequently, this impacts product quality as well as the overall company profitability and efficiency due to scrap or rework requirements.

Component incoming quality control should include the following checks:

  • Correct part numbers and identification marks
  • SMT components are inspected for proper reel packing and solder band quality
  • Inspection of sealing and manufacturer's identification marks (manufacturer seals the device packet in Inert atmosphere)
  • Date of manufacture is checked thoroughly (components older than 6 months are not accepted)

In general, all production materials should be subjected to inspection. All material and parts should be tested or inspected according to specified engineering drawings or technical data sheets.

 

Electrostatic Discharge (ESD)

Some of the components will be sensitive to electrostatic discharge and mishandling of components by inspectors could damage components during the actual inspection process. Therefore, it is paramount that safe handling procedures are in place and implemented by all staff that need to contact the actual components.

Electrostatic discharge or commonly referred to as ESD can occur in a number of different forms with the most common being through human contact with sensitive devices. Some of the other sources of ESD that should be considered at IQC are:

  • Close proximity of synthetic materials such as Styrofoam and other packaging materials
  • Rapid movement of air such as compressed air

Both of these scenarios should be avoided within the inspection area.

Certain components may require specialized inspection equipment such as digital cameras, digital scales, scanners, and microscopes. Whatever the equipment required, it is important that the components are checked using that specific item. Otherwise, defective components could be accepted simply because the inspection equipment is misused.

All IQC should be carried out in accordance to a sampling plan, for example; ANSI ASQ Z1.4 – 2008 STANDARD, LEVEL II, SINGLE SAMPLE with an acceptance quality limit (AQL) of: Critical Defects: 0.4%, Major Defect: 0.65%, Minor Defect: 1.0%.

Other aspects to look out for are RoHS compliancy of any product being delivered to the factory; this particularly applies to any solder related products.


 

22 Signs Of Good Factory Management in China eBook

Topics: Process Improvement

Renaud Anjoran

Renaud Anjoran

15 years experience in China.
Partner, China Manufacturing Consultants.
Worked with hundreds of factories in China.
Certifications: ASQ CQE & CRE; ISO 9001 & 14001 lead auditor.
Author of well-read blog, Quality Inspection Tips.

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