Issue link: https://iconnect007.uberflip.com/i/963057
APRIL 2018 I PCB007 MAGAZINE 29 Cracks in the PCB such as distorted zones around plated through-holes (PTH), at inter- faces, or in the bulk material must be stud- ied. Cracks in the resin could result from tem- perature degradation, high pressure, bending and/or mechanical load. In addition, the per- formance of the PCB material at high voltages needs to be investigated. All of this is neces- sary to guarantee the isolating properties of the PCB. Figure 12 shows an overview of typical failures in PCBs which could produce shorts and current leakage. Figure 11: Material and design qualification by SIR measurements at worst case conditions in closed housings. (Source: Bosch) Figure 12: Failure modes inside the PCB. Humidity-induced failures will gain importance due to increased field load (especially in Asian markets). (Source: Bosch) Automotive Electronics | AE/EAI1 | 12/10/2017 Bosch GmbH 2017. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights. Load capability of design elements on PCB: Test vehicle according to standard IPC-9202 5 6 7 8 9 10 11 12 13 0 30 60 90 120 150 Log IR (W) Time (hour) A4d-1 A4d-2 A4d-3 A4d-4 A4d-5 A4d-6 50V Critical structures Uncritical structures Heat dump cycle (25/55 °C, 90-100% r.h.) Conductive anodic filament (CAF), hollow fibres Cracks in resin by mechanical load and T-degradation Electronics | AE/EAI1 | 12/10/2017 Bosch GmbH 2017. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights. Core – prepreg High pressure CAF failure High stress Hollow fibre