Factory Auditing & Assembly Line Evaluations

Exponent conducts engineering audits of manufacturing facilities to help ensure suppliers follow best practices in manufacturing processes and quality control.  Our auditing programs have been developed from our extensive background in failure analysis and are designed to help the manufacturer improve performance of the process and quality of the product while minimizing the risk of field failures.  While our engineers have a strong background in ISO 9001 auditing techniques and principles, the value we provide comes from our knowledge on how products fail in field and how the manufacturing process can contribute to such failures.  As such, the focus of our audits is process-oriented, where the root of most manufacturing problems occurs, rather than only the quality system associated with the process.

In addition to full factory audits, which include an evaluation of the entire manufacturing process from incoming material quality control (IQC) to outgoing quality control (OQC), Exponent frequently visits manufacturing lines as part of our root-cause analysis investigations.  After examining failed products and understanding the symptoms, it is frequently extremely useful to examine the manufacturing process to understand what role, if any, various manufacturing and handling processes could have played in the failure.  This includes contamination, mechanical defects and deformation, tolerance errors, physical and chemical control parameter settings, etc.

Exponent audits are intended to help assess whether factories are following good manufacturing practices, including the following procedures:


  • Real-time process monitoring and QA
  • Statistical process control
  • Implementation of controls and tests for known failure modes
  • Defective parts removal and destruction
  • Records/record keeping
  • Quality of documentation
  • Inventory control
  • Periodic sampling and testing
  • Final inspection and check
  • Proper packaging
  • Product returns and failure investigations

The typical output of an audit includes an audit report and action item list, where observations are made and possible corrective actions suggested.  The significance of each observation is given a ranking to help the client and vendor focus on the most pressing items first in implementing corrective actions.

In addition to manufacturing audits, Exponent engineers often assist clients in helping develop quality process audit (QPA) documents to facilitate the client’s vendor and supply chain management program.  Quality process audits (QPA) and quality system audits (QSA) are designed to give relative scoring to multiple vendors.

The QPA is a document that Exponent creates with a separate spreadsheet in a workbook for each of the steps in the manufacturing process based on our experience with such technologies.  Each of the spreadsheets contains up to ~50 questions which are scored 0, 1 or 2, depending on the observations at the factory.  We issue an overall audit score as well as an audit score for each of the manufacturing steps.  Using this methodology, a pass, conditional pass, or fail can be given to various vendors based on scores obtained.

Portions of the MLCC QPA document created by Exponent are shown here as an example:

Factory audits conducted for clients in the past include:


  • Battery cell (a range of chemistries)
  • Battery pack assembly
  • Metal casting
  • Polishing/grinding/finishing
  • Surface treatment
  • Connectors
  • Capacitors
  • Inductors
  • Resistors
  • Varistors
  • Flip chips
  • Clean room evaluation
  • Semiconductor fabs
  • Multi-layer boards (PCB)
  • LED and LCD displays
  • PCBA
  • Adhesive application and curing
  • Metal forming
  • Anodization
  • System assembly
  • Injection molding
  • Ambient light sensor plating

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