With the popularity of mobility devices, large of electronics are used in Internet of Things (IoT) and Internet of Vehicles (IoV) applications, especially the new product: electric vehicles (EV) adopts lots of electronics as well. Because this industrial revolution, automotive electronics face the harder challenge than fuel vehicles, and printed circuit board (PCBs) is still the key component of electronics which needs to be paid more attention. Validation of automotive PCB not only can follow up the requirement with the IPC-6012DA verification specifications, which established by the international organization IPC—Association Connecting Electronics Industries, but also has to meet the compliance with customized specifications from various OEMs and Tier 1 supplies in order to ensure that the product quality already satisfied the high reliability requirement.

From experience in automotive PCB verification, DEKRA iST has converged most of the quality problems of PCB through more critical testing items:
 
  • Connectivity issue
The most commonly connected issues are Plating Through Hole (fig.1) and cracked Blind(fig. 2) or Buried Hole, causing an abnormal, electrical open circuit.
Fig. 1 Cracked Plating Through Hole wall  Fig. 2 Blind Hole cracked at the bottom

For the abnormal described as above, Thermal Shock Test (TST) could verify PCB’s potential problems caused by sudden exposure to temperature differences, the changing rate of contact resistance would not exceed the standard. As for automotive PCB verifies that in addition to the temperature change conditions, the current is increased to simulate the use state to make the test environment more stringent.
 
  • Insulation Issue
The most common issues resulting from poor surface insulation or abnormalities in process/materials are decreased insulation resistance to cause poor insulation. The extent of serious electrical anomalies caused by short circuits can be seen in fig.3 & fig.4.
Fig.3 Abnormal Insulation 
between surface traces  
Fig.4 Conductive Anodic Filament(CAF) 
between via holes

The most common acceleration factors to verify for insulation include temperature, moisture and bias; in any kind of test conditions, the main purpose is to verify that the automotive PCB meets the required standard. Each component supplier for automotive PCB has the specifications and methods for the test. It is important to follow the standard and to ensure that your product and process abilities can meet high-reliability requirements; these are the goals of each company.
 
  • Delamination or laminate crack issue 
Automotive PCBs have begun to implement concept of green environment. Although the adoption of lead-free process is relatively slow, during the verification, automotive PCB also encounters the similar failure mode, just like the RoHS implement of ICT industry in 2006. However, the material and manufacturing processes of automotive PCB must be verified with a higher level of reliability.
Fig.5 Reflow simulation facility Fig.6 Delamination image of PCB through SAT

To verify the delamination of PCB, the reflow simulation test can be used to verify the heat resistance of the PCB. The key parameter of this method is the profile of the temperature of the reflow oven corresponding to the actual board temperature, as for the temperature requirement, IPC and IEC standards or the specification from the component suppliers can be followed. Another important point is the inspection method after reflow simulation, includes visual inspection or SAT (Scanning Acoustic Tomography) could find the abnormal spot, these are for non-destructive analysis. Then the next step could use destructive analysis (Micro-section) find the abnormality and root cause to improve PCB manufacturing process.

As for automotive PCB verification, DEKRA iST is experienced in offering the comprehensive testing services to customer, expertise service and verification methodology planning etc. 

 

Contact:Mr. Peng | ext:7501

E-mail :  web_PCB@dekra-ist.com