SMT NADCAP AC7120 Audit Requirements

SMT NADCAP AC7120 Audit Requirements
NADCAP is a certifICation system for special project management systems of national aviation and aerOSPace companies and national defense contractors or authorized projects AC7120 is an audit standard PCB assembly, covering pcb assembly and manufacturing process, such as CAD (Computer Aided design) data, programming, component placement, AOI (Automated Optical Inspection) or X-ray machine inspection, wave soldering, reflow soldering, manual welding, assembly, cleaning, coating and sealing, final test (flying probe, needle bed, boundary test, functional test), rework, etc
AC7120 audit is mainly divided into two parts: file audit, which mainly checks whether the working procedures and specifications meet the requirements of audit terms, and whether they are complete and sufficient; The effectiveness of implementation is mainly to check whether it is effectively implemented through model making (customer requirements, industry requirements) and meets archive requirements.
2.1 Basic audit requirements
Circuit board

Although AC7120 is an audit requirement for process compliance PCB assembly manufacturing technology, there are some basic requirements that can be generally used for other production line control, such as:
a) Personnel requirements: IPC of operators and inspectors, visual examination certificate; Familiar with various specifications and locations; Work as required.
b) Data requirements: specified in the design drawings; Conform to ESD (electrostatic discharge)/MSD (humidity sensor) control; Identification and control of use expiration date, opening expiration date and subcontract expiration date; Enter the required agency acceptance; Periodic tests in use.
c) Equipment requirements: maintenance checklist; Authorized personnel operate the equipment; Configuration of various monitoring equipment; Test and save each shift;
d) Process requirements: meet international or industrial standards; Confirmation and test after each process; Program control; Rationality of process method;
e) Environmental requirements: temperature, humidity, ESD requirements in EPA (electrostatic protection area), noise, illumination and cleanliness.
These required files will be reviewed by the auditor during the audit and verified item by item during the on-site audit.
2.2 Quality control requirements
2.2.1 Focus on quality system
AC7120 professional audit is always based on the implementation of the requirements of the organization's quality control system, specifically involving: quality manual, procedure and file control, personnel qualification, environmental requirements, data control, supplier control, first article identification, nonconforming product management and corrective measures, the effectiveness of QA (quality assurance, quality assurance) personnel, internal audit, combined with process audit requirements, will be audited and implementation evidence will be required.
2.2.2 Pay attention to the effectiveness of corrective measures
Pay attention to the effective implementation of corrective measures for nonconformities and the verification of results in the last review process. If the corrective measures have not been effectively implemented and maintained for a long time, AC7120 professional audit will issue two serious nonconformities: one is repetitive problems, and the other is that the system cannot maintain the effectiveness of the corrective measures.
2.2.3 Attention to traceability
Any data must be traceable to the original manufacturer's batch number, especially COC must be attached to the first article report. All data on the site must have subcontracting labels, indicating: data name and specification, original package validity, batch number, opening validity, subcontractor, and data batch number must be transplanted together with the work order. The archives of all products shall be kept permanently, and all on-site production records shall be kept for more than 5 years.
2.3 Requirements for process discipline
2.3.1 ESD control
Electrostatic control is the first control of EPA area: the hardware facilities (floor, table mat, chair, etc. must be made of anti-static materials), equipment grounding and other objects in this area should be made of anti-static materials (turnover box, trash can, tweezers, oil suction pen). If there is no condition to use the anti-static data, the ion blower should be included during the operation.
Static control of electrostatic discharge data, anti-static pocket, wear anti-static wrist strap when taking and placing.
Electrostatic control personnel, daily check anti-static shoes and wrist test.
2.3.2 MSD control
The humidity sensitive equipment needs to identify the liquid level, dry according to the original manufacturer's prompts before assembly, and follow the assembly and use requirements within the service life of the workshop.
2.3.3 PCB cleaning
Because PCBs involve many processes, there is still some time to complete the assembly after welding the first side It is applicable to manufacturers who deliver complete machines. PCB veneer needs to be cleaned after commissioning, and PCB is usually cleaned more than 8 hours after welding At this time, the cleaning effect can no longer remove the polychlorinated biphenyls on the surface, which is the most effective. In retrospect, NADCAP AC7120 stipulates that polychlorinated biphenyls should be cleaned within 8 hours after welding If water cleaning or half water cleaning is used, a drying time of 4 hours is required, which will greatly limit the process cycle of the production line. Therefore, vapor phase cleaning can be considered
2.3.4 Rework and repair control
In the industry standard, there is only one limit on the number of rework and repair, but NADCAP AC7120 emphasizes that rework is not allowed, and the customer must be consulted during repair.
The process discipline requires mainly to review the effectiveness of on-site implementation, which is also the focus of AC7120 audit. During the on-site audit, attention shall be paid to whether the provisions are correctly traceable, whether the implementation is accurate and in place, whether the records are complete, and whether the operators can obtain the latest and effective guidance files. All specified requirements are commitments of the organization and must be realized in the process.

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