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Method for a flux and solder paste viscosity measurement

IP.com Disclosure Number: IPCOM000012349D
Publication Date: 2003-Apr-30
Document File: 3 page(s) / 97K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a flux and solder paste viscosity measurement. Benefits include an improved development environment and improved performance.

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Method for a flux and solder paste viscosity measurement

Disclosed is a method for a flux and solder paste viscosity measurement. Benefits include an improved development environment and improved performance.

Background

              A poor correlation exists between the viscosity measured using a commercially available viscometer and the actual stencil printing performance of materials such as fluxes and solder paste. This disparity occurs because commercially available viscometers do not simulate the actual forces that act on fluxes and solder paste during stencil/screen printing.

              A commercially available solution uses the Archimedes screw concept to apply a shear force to the flux/solder paste while measuring the flux/solder paste viscosity (see Figure 1).

General description

              The disclosed method is a flux and solder paste viscosity measurement. The method includes an apparatus for measuring the viscosity of stencil-printed fluids.                                          The key elements of the method include:

•             Use of Newton’s concept of viscosity to measure the instantaneous viscosity that represents the actual forces that act on the fluids during stencil/screen printing

•             Design of the apparatus to measure the viscosity of fluid when shear force due to screen/stencil printing is applied

•             Mathematical simplification and assumptions made to Newton’s concept of viscosity to determine the viscosity of the fluid under shear force due to screen/stencil printing

Advantages

              The disclosed method provides advantages, including:

•             Improved development environment due to simulation of the actual conditions that act on screen-printed fluids/paste, providing a more accurate viscosity measurement by using Newtonian principles

•             Improved performance due to a more accurate viscosity measurement

Detailed description

      Newton’s concept of viscosity is applied to measure the instantaneous viscosity that represents the actual forces that act on the fluids when stencil/screen printing. The shear force exerted on the flux is measured using a force sensor that is attached to the squeegee (see Figures 2 and 3). The shear force sensor is connected to a shear...