Solvent Selection Cleaning Process Options Why do

Solvent Selection Cleaning Process Options

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

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

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

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

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

Vapor Degreasing LENIUM GS, 3 M HFEs Aqueous ALPHA 2110 HYDREX SP / SP-50 KYZEN 4520 ZESTRON AC 200 Semi-Aqueous Types of Cleaning Options Evaporative Solvents IPA, Acetone, MEGASOLV JB, AXAREL 2200 BIOACT EC-7 R AXAREL 32 / 36 / 46 BIOACT SC-22

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

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

Cleaning Trade-offs

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

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

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

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 become acidic with water contamination – VOC issues

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