Rheological characterization of solder pastes for surface mount applications

Kolli, Venkata Giri; Gadala-Maria, Francis; Anderson, R.

doi:10.1109/96.641510

Cited by 26 publications

(8 citation statements)

References 13 publications

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“…The drop in viscosity could have been due to the sample fracturing either at the interface or at the bulk material. A previous study by Kolli et al (1997) on solder pastes, observed internal slip in the bulk of the solder paste sample about midway between the gap heights, ultimately leading to the expulsion of part of the sample. The author also found that the time at which this internal slip occurred was approximately ten seconds after the test was underway and thereafter, shear fracture was observed to take place in the samples.…”

Section: Effect Of Surface Roughness Of Parallel Plate Geometry On Thmentioning

confidence: 93%

“…The formation of wall-slip is usually seen as a source of error in the rheological measurements and various steps have been taken to eliminate or reduce wall-slip (Kolli et al 1997). However, in some cases the wall-slip is important because most material production involves flow through some form of complex geometry which is surrounded by walls.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of wall-slip effect on lead-free solder paste and isotropic conductive adhesives

Durairaj

Mallik

Seman

et al. 2009

Sadhana

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Slippage due to wall depletion effect is well-known in rheological investigation. The aim of this study was to investigate the influence of the paste microstructure on slip formation for the paste materials (lead-free solder paste and isotropic conductive adhesives). The effect of different flow geometries, gap heights and surface roughness on the paste viscosity was investigated. The utilisation of different measuring geometries has not clearly showed the presence of wall-slip in the paste samples. The existence of wall-slip was found to be pronounced when gap heights were varied using the parallel plate geometry. It was also found that altering the surface roughness of the parallel plate measuring geometry did not significantly eliminate wall-slip as expected. But results indicate that the use of a relatively rough surface helps to increase paste adhesion to the plates and to a certain extent inducing structural breakdown in the paste. Most importantly, the study also demonstrated on how the wall-slip formation in the paste material could be utilised for understanding of the paste microstructure and its flow behaviour.

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Section: Effect Of Surface Roughness Of Parallel Plate Geometry On Thmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Investigation of wall-slip effect on lead-free solder paste and isotropic conductive adhesives

Durairaj

Mallik

Seman

et al. 2009

Sadhana

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show abstract

“…The most commonly used method to capture the rheological behaviour is through a shear/hysteresis loop test, which entails viscosity measurements where the shear rate increases from a minimum to a maximum value and then returns back to the minimum. The hysteresis loop test has been used to measure the thixotropic behaviour of the solder paste in Kolli et al ’s (1997) and Durairaj et al ’s (2004) studies. This measurement does not provide sufficient time for the viscosity to reach a steady value.…”

Section: Rheological Measurementsmentioning

confidence: 99%

Rheological characterization of non-Brownian suspensions based on structure kinetics

Vachaparambil

Mårtensson

Essén

2018

SSMT

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Purpose The purpose of the paper is to develop a methodology to characterize the rheological behaviour of macroscopic non-Brownian suspensions, like solder paste, based on microstructural evolution. Design/methodology/approach A structure-based kinetics model, whose parameters are derived analytically based on assumptions valid for any macroscopic suspension, is developed to describe the rheological behaviour of a given fluid. The values of the parameters are then determined based on experiments conducted at a constant shear rate. The parameter values, obtained from the model, are then adjusted using an optimization algorithm using the mean deviation from experiments as the cost function to replicate the measured rheology. A commercially available solder paste is used as the test fluid for the proposed method. Findings The initial parameter values obtained through the analytical model indicates a structural breakdown that is much slower than observations. But optimizing the parameter values, especially the ones associated with the structural breakdown, replicates the thixotropic behaviour of the solder paste reasonably well, but it fails to capture the structure build-up during the three interval thixotropy test. Research limitations/implications The structural kinetics model tends to under-predict the structure build-up rate. Practical implications This study details a more realistic prediction of the rheological behaviour of macroscopic suspensions like solder paste, thermal interface materials and other functional materials. The proposed model can be used to characterize different solder pastes and other functional fluids based on the structure build-up and breakdown rates. The model can also be used as the viscosity definitions in numerical simulations instead of simpler models like Carreau–Yasuda and cross-viscosity models. Originality/value The rheological description of the solder paste is critical in determining its validity for a given application. The methodology described in the paper provides a better description of thixotropy without relying on the existing rheological measurements or the behaviour predicted by a standard power-law model. The proposed model can also provide transient viscosity predictions when shear rates vary in time.

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“…(16)(17)(24)(25)(26) Among the surprising phenomena observed during the flow of these multi-phase materials, the wall depletion effect (apparent slip at the wall) is probably one of the most important. (27) Kalyon et al (27) have shown that the contribution of slip to the overall flow rate is negligible in a given range of shear stress, depending on the behavior of the material (shear thinning or thickening).…”

Section: Characterization Of a Concentrated Suspension Using The Penementioning

confidence: 99%

A Penetroviscosimeter for Newtonian and Visco-Plastic Fluids

Picart¹,

Manceau²,

Fauré³

2001

Instrumentation Science & Technology

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The penetration test has been widely used by engineers to characterize the behavior of materials such as soils, fresh concrete, or concentrated suspensions. These approaches provide related measurements to rheological properties by means of empirical parameters. The present paper, based on Bikerman's works,(1) describes an analytical method for a penetration test, for Newtonian or Binghamian fluids.Characteristics of the flow between the bowl and the plunger are determined using an end effect correction method. In the case of Newtonian fluids, the theoretical developments are validated by experiments on a standard material. The material density is also determined using the same measurements.For the Bingham behavior, the total set of equations is presented. The limiting cases of low and infinite velocity are studied and applied to a very concentrated suspension. The viscosity and the yield stress are compared to the results of capillary and vane shear experiments. The same order of magnitude is found. However, we show here that these properties are only equivalent ones for this material, due to the slip motion observed at the penetrometer walls.

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Rheological characterization of solder pastes for surface mount applications

Cited by 26 publications

References 13 publications

Investigation of wall-slip effect on lead-free solder paste and isotropic conductive adhesives

Investigation of wall-slip effect on lead-free solder paste and isotropic conductive adhesives

Rheological characterization of non-Brownian suspensions based on structure kinetics

A Penetroviscosimeter for Newtonian and Visco-Plastic Fluids

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