Recently, a company approached the EMPF Training Center with a request for training on Failure Analysis of printed circuit board assemblies (PCBAs). Normally, the EMPF would recommend the standard Reliability Testing and Failure Analysis course, but this company was interested in a slightly different curriculum focus to meet their needs. The company making this inquiry is a world class manufacturer of printed circuit boards (PCBs) with a number of international manufacturing facilities. Their interest is based on the need to understand how their customers (the users and assemblers of PCBAs) approach failure analysis of assemblies. Their objective is to use their increased knowledge base to act as a partner with their customers when assembly failures are encountered. This avoids the common situation where the PCB assembler and the PCB manufacturer are often at odds with the root cause of assembly failures. 

Based on the company’s requirements, a customized and expanded curriculum on the topic of Failure Analysis of PCBAs was developed. The custom curriculum covers nine main topics:

1. Scanning Electron Microscopy: Training on the theory of operation and applications of Scanning Electron Microscopy (SEM) is presented. Case studies where an analysis with SEM is applied to a PCBA failure are presented and the students are given an opportunity to use the SEM located in the EMPF’s Analytical Laboratory, on their own samples.

2. Energy Dispersive X-ray Spectroscopy: Training on the theory of operation and applications of Energy Dispersive X-ray Spectroscopy (EDX) is presented. The capabilities of EDX are described, as well as techniques that are available to avoid the limitations of EDX. Students are also given an opportunity to work with EDX in the EMPF’s Analytical Laboratory.

3. Solderability Analysis: Training is provided on the solder wetting requirements for PCB solderable surfaces. Solderability test methods provided in IPC documents are presented, including solder float testing and wetting balance testing. The use of X-ray Fluorescence (XRF) on PCB solderable surfaces to indicate potential solderability problems is covered. Finally, a discussion of best practices for storage of PCBs, solders, and flux materials, and the potential effects of poor storage practices on solderability, is provided.

4. Sequential Electrochemical Reduction Analysis: Training on the theory and applications of Sequential Electrochemical Reduction Analysis (SERA) is presented. The requirements for samples undergoing SERA testing are explained and the oxides that can be quantified are described. A laboratory experience is provided for the students using XRF and SERA techniques.

5. PCB Fabrication Defects: Defects in the manufacture of PCBs and the manner in which they manifest as defects in PCBAs are presented. The effects of surface finish defects, solderability defects, solder resist defects, drilling defects, and contamination defects on PCBAs are presented. Cross-sectional analysis techniques are described and the application of Scanning Acoustical Microscopy on multi-layer PCBs is explained.

6. Thermal and Thermo-mechanical Testing: The effects of coefficient of thermal expansion mismatches and mechanical creep as a result of thermal stress testing is presented. Common temperature profiles used in thermal stress testing on PCBAs are described.

7. Design for Manufacturability: The effects of bow and twist on the long term reliability of PCBAs are described and methods to avoid failures caused by bow and twist are presented. The benefits and drawbacks of the use of laser-cut micro vias on Ball Grid Array package sites are explained.

8. Rework and Repair: IPC standards on the topic of rework and repair of PCBAs are presented. Common materials, equipment, and techniques used by PCBA assemblers for rework and repair are explained as well as the effect on long-term reliability of PCBAs that undergo rework and/or repair.

9. Lead Free Soldering and Analysis: The effects of processing PCBAs using lead free solders are presented. Specific information on the differences in metallurgical structures of solder joint between lead-bearing and lead free solders is included. The effect of lead contamination on lead free solder joints is explained. Tin whiskers and the current state of research on tin whiskers are discussed. Defects that occur more commonly when PCBs are exposed to lead free solder processes are presented, including outgassing, delamination, and land lifting.

Customized training courses are available through the EMPF, both at our location and at your facility. To discuss your organization’s specific training needs, schedules for standard courses, or to register for a course, please contact the Registrar at (610) 362-1295 or via email at registrar@empf.org