Purpose

The purpose of this paper is to investigate the effect of different viscosity models (Cross and Al-Ma’aiteh) and different printing speeds on the numerical results (e.g. pressure over stencil) of a numerical model regarding stencil printing.

Design/methodology/approach

A finite volume model was established for describing the printing process. Two types of viscosity models for non-Newtonian fluid properties were compared. The Cross model was fitted to the measurement results in the initial state of a lead-free solder paste, and the parameters of a Al-Ma’aiteh material model were fitted in the stabilised state of the same paste. Four different printing speeds were also investigated from 20 to 200 mm/s.

Findings

Noteworthy differences were found in the pressure between utilising the Cross model and the Al-Ma’aiteh viscosity model. The difference in pressure reached 33-34% for both printing speeds of 20 and 70 mm/s and reached 31% and 27% for the printing speed of 120 and 200 mm/s. The variation in the difference was explained by the increase in the rates of shear by increasing printing speeds.

Originality/value

Parameters of viscosity model should be determined for the stabilised state of the solder paste. Neglecting the thixotropic paste nature in the modelling of printing can cause a calculation error of even approximately 30%. By using the Al-Ma’aiteh viscosity model over the stabilised state of solder pastes can provide more accurate results in the modelling of printing, which is necessary for the effective optimisation of this process, and for eliminating soldering failures in highly integrated electronic devices.

中文翻译：

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锡膏流变行为和印刷速度对模板印刷影响的数值研究

目的

本文的目的是研究不同的粘度模型（Cross和Al-Ma'aiteh）和不同的印刷速度对有关模版印刷的数值模型的数值结果（例如，模版上的压力）的影响。

设计/方法/方法

建立了有限体积模型来描述打印过程。比较了非牛顿流体性质的两种粘度模型。在无铅焊膏的初始状态下将Cross模型拟合到测量结果，在相同焊膏的稳定状态下拟合Al-Ma'aiteh材料模型的参数。还研究了从20到200 mm / s的四种不同的打印速度。

发现

发现在使用Cross模型和Al-Ma'aiteh粘度模型之间的压力之间存在显着差异。对于20和70 mm / s的打印速度，压力差分别达到33-34％，对于120和200 mm / s的打印速度，压力差分别达到31％和27％。差异的变化可以通过增加印刷速度来增加剪切速率来解释。

创意/价值

对于焊膏的稳定状态，应确定粘度模型的参数。在印刷建模中忽略触变膏的性质会导致大约30％的计算误差。通过使用Al-Ma'aiteh粘度模型在锡膏的稳定状态上可以在印刷建模中提供更准确的结果，这对于有效优化此过程以及消除高度集成的电子设备中的焊接失败是必需的。