Progressive Energy Dynamics: Key to Low Standoff Cleaning

Progressive Energy Dynamics: Key to Low Standoff Cleaning The AAT Advantage PED The Science of Cleaning

1. What’s the Problem ? • Space under components is shrinking • Interconnect densities are increasing • Performance requirements are increasing • Lead-free & no-clean are harder to clean • Fluxes are fully filling small gaps

Fluid Flow Theory – • Cleaning Small Gaps • Depends on 2 things - - - • Physical properties of the cleaning agent • (surface tension, density and viscosity) • 2. Higher energy fluid delivery • (flow rate and impact velocity) • Energy Delivered is dependent on equation for Kinetic Energy • Kinetic Energy @ the surface = mass x velosity2 @ the surface

How much energy does it take to clean tight spaces? • Interfacial pressure differential calculation NOTE: if θ is greater than 90˚, as with water on waxy surface, the force becomes negative or repulsive. If surface is wetted, force pulls the fluid into the gap. planar cylinder γ = surface tension Θ = contact angle of liquid at surface R = radius meniscus

2. Fluid Flow Theory – Small unfilled Gaps • Relationship between gap size and capillary force for water on glass Interfacial pressure difference at equilibrium psi 10 Planar: Cylinder: 1 0.1 0.01 0 20 40 60 Gap/diameter, mils

Surface effects in tight spaces retard fluid flow (computer model of flow in 50 micron gap) Component

And that’s the easy stuff!

3. Fully Filled Gaps are Much Harder (Resistors, Capacitors, LCC’s, QFN’s)

3. Fluid Flow Theory – Filled Gaps • 3 steps are required to remove a fully blocked gap: 1 Outer solvent depleted zone softened 2 Liquid jet with sufficient energy forms flow channels 3 Bulk residue is eroded & dissolved by fluid flow Steps 2 & 3 require substantial Energy

Research leading to PED

1 3 4 5 6 2 Final Rinsing Pre-Wash Chemical Isolation Rinse Dryer Wash 4. Inline Progressive Energy Dynamics Approach (PED) Treatment system • PED Works in a standard in-line configuration

4. Inline Progressive Energy Dynamics Approach • New approach to design in-line cleaner • Involves a manifold design with increasing energy at each manifold Pre-wash Wash 1 Wash 2 Wash 3 Low Energy Jet Medium Energy Jet High Energy Jet Highest Energy Jets Heat & wet penetrate form flow erode surfaces outer layer channels flux

4. Inline Progressive Energy Dynamics Approach • Wash section equipped with progressive energy dynamics Soften Outer Shell Create Flow Channels Erode Flux Residue

4. Inline Progressive Energy Dynamics Approach • AProgressive Energy Designis: • A fluid delivery system • Recognizes the 3-step process required to clean flux-filled spaces • Delivers only what is needed at each step: 961 I/O “glass on glass” Flip Chip

Progressive Energy Dynamics: Key to Low Standoff Cleaning

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