Further enhancements to Speedline MPM's Rheometric Pump

Soldering & Surface Mount Technology

ISSN: 0954-0911

Article publication date: 1 April 2000




(2000), "Further enhancements to Speedline MPM's Rheometric Pump", Soldering & Surface Mount Technology, Vol. 12 No. 1. https://doi.org/10.1108/ssmt.2000.21912aad.021



Emerald Group Publishing Limited

Copyright © 2000, MCB UP Limited

Further enhancements to Speedline MPM's Rheometric Pump

Further enhancements to Speedline MPM's Rheometric Pump

Keywords: Speedline MPM, Pumps

Speedline MPM's Rheometric Pump Print Head system (Plate 8) has been further enhanced by a series of technological refinements. The pump system now features variable volume actuator (VVA) technology to offer unsurpassed levels of paste control, deposition accuracy and repeatability.

Plate 8MPM VVA Rheopump

The Rheometric VVA Pump Head applies paste, which is fed from a patented air-tight chamber, directly to a board. As it moves across a stencil, the combination of pneumatic pressure applied to the paste cartridges and friction between the paste and stencil causes the paste to continuously roll and mix within the chamber.

Speedline MPM's patented balanced control print head and tactile sensor technology is also used to ensure that the head and board are aligned exactly at all times. It also allows the head to "float" across the stencil and adapt to the changing topography of the board to constantly maintain a consistent seal with the stencil surface. The result is that a precise bead of paste is "pumped" directly into the stencil apertures. This is separated cleanly from the main body of paste in the chamber by the tips of a metal shear blade beneath the Rheometric VVA pump head. This also dramatically reduces paste waste by as much as 30-50 percent because no excess paste is left on a board during printing.

Unlike conventional squeegee-based printing, major problems stemming from consistency variations in having solder paste rolling on to the stencil in open air are completely eliminated because the paste is fully protected within the sealed print head and only comes into contact with the stencil at the point of application.

The viscosity of the paste is maintained through a unique, sealed circular chamber design that does not allow for dead spots or exposure to the air. Key to VVA technology is the use of specialised U-cupped pistons which maintain consistent chamber pressure distribution across the opening. At the end of the print stroke, the pistons retract, relieving pressure in the chamber for greater material control and less paste waste.

The Rheometric VVA pump head system also uses new Permalex impregnated metal squeegee blades and polyurethane-based sidedam composites for superior print deposition and longer wear characteristics. The blades also enhance the rolling action of the paste within the Rheometric chamber.

The Rheometric VVA pump head system accepts 6oz, industry standard paste cartridges, eliminating the need for special packaging or messy refilling of bladders. And to minimise paste costs, proximity sensors are used to ensure that the paste cartridge is completely empty before replacement.

The Rheometric VVA pump head comes in 8, 10, 12, 14 and 16-in. head sizes to allow it to adhere to a large variety of board and stencil sizes. New under-stencil supports also prevent small paste smears from being left on the stencil surface in unsupported areas.

The Rheometric VVA pump head can be quickly removed for cleaning or re-installed after refrigerated storage using Speedline MPM's Quick Disconnect system. These quick disconnects, combined with the elimination of stencil cleaning, result in a significant reduction in cycle times and an equally dramatic gain in through-put.

The Rheometric VVA pump head option is currently available on Speedline MPM's Ultraprint 3000, 2000 and AP printers, and will be available on the Ultraprint 500 in quarter three of 1999. The pump head is also offered as an upgrade for existing printers in the field.

For further information please contact: Zoe Oliver, Speedline Technologies, Unit 1, Pincents Kiln Industrial Park, Reading RG31 7SD, UK. Tel: +44 (0) 118 930 1400; Fax: +44 (0) 118 930 1401; E-mail: zoliver@speedline.cookson.com

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