Attila Geczy, Márta Fejos and László Tersztyánszky
This paper aims to reveal the causes and find an efficient method to compensate the shrinkage to reduce failure costs. Reflow-induced printed circuit board (PCB) shrinkage is…
Abstract
Purpose
This paper aims to reveal the causes and find an efficient method to compensate the shrinkage to reduce failure costs. Reflow-induced printed circuit board (PCB) shrinkage is inspected in automotive electronics production environment. The shrinkage of two-sided, large PCBs results in printing offset errors and consequently soldering failures on smaller components during the reflow soldering of the second PCB side.
Design/methodology/approach
During the research, the investigations had to adapt to actual production in an electronics manufacturing plant. A measurement method was developed to approximate the overall shrinkage of the given product. With the shrinkage data, it is possible to perform an efficient compensation on the given stencil design in computer-aided manufacturing environment.
Findings
It was found that even with the investigated lower-quality PCB materials, the compensation on the stencil significantly reduces the quantity of failures, offering an efficient method to improve the yield of the production.
Research limitations/implications
Research was oriented by the confines of production (fixed PCB sources, given PCB materials, reflow process and production line), where an immediate solution is needed. Future investigations should be focussed on the PCB parameters (different epoxy types, glass-fibre reinforcements, etc.).
Practical implications
The optimised production reduces overall failure costs. The stencil re-design and application is a fast and efficient way to immediately act against the shrinkage-induced failures. The method was successfully applied in automotive electronics production.
Originality/value
The paper presents a novel approach on solving an emerging problem during reflow.
Details
Keywords
Oliver Krammer, László Jakab, Balazs Illes, David Bušek and Ivana Beshajová Pelikánová
The attack angle of stencil printing squeegees with different geometries was analysed using finite element modelling.
Abstract
Purpose
The attack angle of stencil printing squeegees with different geometries was analysed using finite element modelling.
Design/methodology/approach
A finite element model (FEM) was developed to determine the attack angle during the stencil printing. The material properties of the squeegee were included in the model according to the parameters of steel AISI 4340, and the model was validated by experimental measurements. Two geometric parameters were investigated; two different unloaded angles (45° and 60°) and four overhang sizes of the squeegee (6, 15, 20 and 25 mm).
Findings
It was found that the deflection of the blade is nearly homogenous along the length of the squeegee. This implies that the attack angle does not change significantly along the squeegee length. The results showed significant differences between the initial and the attack angle. For example, the angle of the squeegee with 15 mm overhang size and with 60° initial angle decreased by more than 5° for a specific squeegee force of 0.3 N/mm; resulting in an attack angle of 53.4°.
Originality/value
The attack angle during the printing is considerably lower than the initial angle as a result of the printing force. The papers, which were dealing with the numerical modelling of the stencil printing presumed that the squeegees were having their initial angle. This could have led to invalid numerical results. Therefore, we decided to investigate the attack angle during stencil printing for squeegees with different initial geometries to enhance the numerical modelling of stencil printing.