PTH Lifetime Predictor for TC

Leveraging on results obtained from earlier Thin Cu Plating project, this project aimed to establish a popular equation to predict PTH lifetime, focusing on PWB used in the telecommunication equipment, computers and servers. Using finite element method (FEM) and applying Box-Behnken experimental design, seven PWB factors were initially analysed, by simulating pressures acting on several PWB models, under various operating environments. The relationships of these factors were established to derive the PTH lifetime predictor for TC (Temperature Cycling). Thermal cycling tests (TCT) were performed to compare the physical time to failure with the simulated one. 

Project stage: 
Lead company: 
Fujitsu

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Idea Information

Background: 

The lifetime of the printed circuit board and your product is very dependent on how long the PTH will last.  The PTH reliability is dependent on several variables such as the thickness of the board, the quality and plating in the hole, the thickness of the plating as well as connection interface between the in inner layer and the PTH. There is no currently no mathematical predictor established to predict PTH lifetime.

Problem: 

The conventional approach to predict PTH lifetime is to perform Accelerated Temperature Cycling which is very time consuming. For BGA/LGA solder joint, the modified Coffin-Manson equation has been established to predict its lifetime. For PTH, there is currently no such accelerated equation.

 

PCB PTH

BGA/LGA Solder joint

Temperature Cycling Test (ATC)

Conventionally-used

Conventionally-used

FEM Simulation+Life prediction

Established in Thin

 Cu plating PJ

2012-2014

Established in

Mechanical Fatigue Test PJ

2009-2011

Life prediction by

 accelerated equation with  

 parameters(factors)

 

 

No popular Equation

2015-2018?

Norris-Landzberg Equation

(Modified Coffin-Manson Equation)

Definition Information

Goals / Benefits: 

This project aims to establish a popular equation to predict PTH lifetime, focusing on PCB used in the telecommunication equipment, computers and servers.

This equation can be used to give a more accurate prediction of the product warranty period and cost based on the product’s operating environment. It can also be used to find PTH critical design factors to fine-tune the PTH design at the early PCB design stage, bringing improvement to product lifespan.

 

Approach: 

Leveraging on results obtained from earlier Thin Cu Plating project, this project uses final element method (FEM) to simulate the pressures acting on several PCB models, under various operating environments. Temperature cycling tests will then be performed on the PWB and the results compared with the FEM data collected to determine the accuracy of the equation to be established.

Seven PCB factors will be simulated at three levels using Box-Behnken design. Phase 1 with 2 sets of 62 runs will analyse the effects of these factors and the various interactions between two factors. Using the data analysed in Phase 1, Phase 2 will refine the factors for further FEM simulation runs so as to better understand the effects and the interactions of the factors. The relationships of these factors will then be established and subsequently optimized to derive the PTH lifetime predictor for TC.

Phase 1 Factors

 

Phase 2 Factors

Public