Dipping Paste combines solder spheres and flux vehicle.

Press Release Summary:

Comprising of Sn96.5/Ag3.0/Cu0.5 with solder powder size of 4-24 microns, LFM 48 N paste suits package warpage and package-on-package fluxing applications during reflow. Paste delivers consistent dipping transfer characteristics coupled with strong tack performance to hold large devices firmly in position on high speed Pick and Place systems. It features designed Open Time in dipping tray of 8 hr (at 23°C and 50% RH) and up to 8 hr process window time between dipping and reflow.

Original Press Release:

New Dipping Paste from Almit Addresses Device Warpage & PoP Applications

At National Electronics Week, Stand C18, Almit Ltd is launching a new dipping paste featuring strong tack performance and wetting force to cater for significant package warpage and Package-on-Package fluxing applications during reflow.

Almit's new LFM 48 N Dipping Paste is a powerful alternative to gel pastes traditionally used in BGA PoP (Package-on-Package) stacked device applications and is ideal for holding larger area devices that often exhibit warpage during reflow. The new paste is a combination of ultra-fine solder spheres and a flux vehicle optimised for a long open time in a dipping tray. It offers reliability advantages to board assemblers at both solder melt and peak reflow temperatures.

LFM 48 N is expressly designed to deliver consistent dipping transfer characteristics coupled with a strong tack performance to hold large devices firmly in position on high speed Pick & Place systems. It deploys Almit's proven low-voiding, thermally stable flux technology to guarantee a strong wetting force between molten solder and pad areas. This force is maintained throughout the entire reflow cycle to eliminate de-wetting tendencies and thereby eliminate the likelihood of open circuit interconnections arising from the warping force of the package.

"Increasingly in BGA PoP applications, we see the devices are getting thinner to minimise overall component height, and this makes them more prone to warping during reflow," explains Peter Martin, MD of Almit.

In PoP assembly, the first device is placed into wet solder paste on the PCB. The next device to be stacked is typically dipped into gel flux and then placed on top of the first. Here, LFM 48 N delivers superior performance and greater reliability, especially where warpage during reflow of the first device impacts the ability of the solder balls on the underside of the second device to reflow successfully across an enlarged gap. "Using a dipping paste rather than just a flux simply adds more paste to the process and guarantees a better joint," Martin points out.

Almit's new no-clean, lead-free LFM 48 N Dipping Paste formulation comprises Sn96.5/Ag3.0/Cu0.5 with a solder powder size of 4 to 24 microns (Almit size 'N'). It features a designed Open Time in a dipping tray of eight hours (at 23°C & 50% RH) and up to eight hours process window time between dipping and reflow.

Almit Ltd can be seen at National Electronics Week on Stand C18.

Almit contact
Chris Ward
Almit Technology Ltd
Unit 7 Forest Row Business Park
Station Road
Forest Row
East Sussex
RH18 5DW
Tel: +44 (0)1342 822844
Email: chris@almit.co.uk

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