Cleaning Process Options

1. Cleaning Process Options Solvent Selection

2. Why do we Clean? • We clean to ensure product reliability • remove ionic / acidic contamination and particulates that can cause problems in use of the product • We clean to prepare surfaces • remove oils and flux residues that can inhibit the bonding of conformal coatings / insulation coatings • remove flux residue from underfill areas • prepare surfaces for bonding or coating • We clean to meet specification requirements • because it is in the contract

3. Was No-Clean technology developed by Military Intelligence? The phrase “No-Clean” is incorrect. These types of fluxes and pastes correctly should be referred to as “Synthetic” Fluxes Many “Synthetic” fluxes and pastes are cleaned Steve Stach / AAT

4. No-Clean Fluxes really are Synthetic Fluxes • Traditional fluxes are limited • Rosin fluxes must contain rosin • Inherently sticky • not as printable for Fine Pitch • Water solubles must be water soluble • Shorter printing life, less tack • harder to process -must be cleaned • Synthetic Fluxes have no formulary restrictions • Can be formulated to optimize the process • Printability, tack, printing life, cleaning or no clean Steve Stach / AAT

5. Flip Chip cleaning prior to under-fill improves reliability by preventing under-fill voids and delamination Delamination of under-fill will cause premature solder failure Under-fill Void traps foreign matter and concentrates physical force Steve Stach AAT

6. Lead free soldering requires stronger fluxes/cleaning or nitrogen oven inertion No-lead residues are discolored due to higher temperature profiles

7. Vapor Degreasing LENIUM GS, 3M HFEs Aqueous ALPHA 2110 HYDREX SP / SP-50 KYZEN 4520 ZESTRON AC200 Semi-Aqueous BIOACT EC-7R AXAREL 32 / 36 / 46 BIOACT SC-22 Types of Cleaning Options Evaporative Solvents IPA, Acetone, MEGASOLV JB, AXAREL 2200

8. Cleaning Technologies with Differing Benefit Trade-offs • Aqueous Cleaning • Evaporative Solvent Cleaning • Semi-aqueous Cleaning • Vapor Degreasing • Out-Sourced Cleaning

9. Cleaning Options • Aqueous • Water Wash with Water Rinse • Semi-Aqueous • Hydrocarbon Wash / Water Rinse • Vapor Degreasing • Heated Solvent Vapor Wash and Rinse • Evaporative Solvents • Hydrocarbon Wash and Rinse • Contract Cleaning • Contractor Responsible for Part Cleaning

10. Cleaning Trade-offs

11. Aqueous Cleaning • Advantages • Low VOCs • Cleans Most Contamination • Chemicals Inexpensive • Equipment low to Moderately Expensive • Short process cycle - inline • Disadvantages • Wastewater Treatment / Neutralization • High Energy Cost • Medium to Long Process Cycle - Batch • Government Restrictions on Water Use

12. Evaporative Solvents • Advantages • Easy to use • Chemicals Relatively Inexpensive • Process Time Under 20 minutes • Good for Cleaning Stencils / CCAs / Misprints • Disadvantages • High VOC Content • Safety concern, Flammable/combustible • Waste Disposal • Can just move dirt around

13. Semi-Aqueous Cleaning • Advantages • High VOCs, but Low Evaporation • Cleans Most Contamination • Chemicals Moderately Expensive • Many Products are Biodegradable • Disadvantages • Moderate Energy Cost • Medium to Long Process Cycle • Good Machines Are Expensive

14. Vapor Degreasing • Advantages • Solvent is Continuously Recycled • Cleans Most Organic Contamination • Process Time Under 10 Minutes • Excellent for Cleaning Fine Pitch / BGAs / Blind Holes / Machined Parts • Disadvantages • Not so good for polar soils • Low to Moderate Energy Cost • Chemicals Must Be Handled Carefully • Chemicals Expensive & volitile • Systems can can become acidic with water contamination • VOC issues

15. Contract Cleaning • Advantages • Contract Professional Manages the Cleaning Process • No Chemicals to Buy; No Maintenance • No Permits to Meet • No Equipment to Purchase • Disadvantages • Not many