1. The Science of Cleaning Green
Progressive Energy Dynamics
(The Key to Low Standoff Cleaning)
The Science of Cleaning Green

2. 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 fillng small gaps

3. Fluid Flow Theory – Cleaning Small Gaps Depends on 2 things. . .
1. 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 the surface = mass x the surface

4. 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

5. 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
Gap/diameter, mils

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

7. And that’s the easy stuff!

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

9. 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

10. Research leading to PED

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

12. 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

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

14. Inline Progressive Energy Dynamics Approach
A Progressive Energy Design is:
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