PROCESS CONTROL AT BENCH TOP CLEANING, HOW NOT TO KILL A CIRCUIT BOARD Russell Claybrook MicroCare Central Region Sales Manager
Reliability Experts Say: Manual soldering and cleaning processes are among the least controlled processes in printed circuit board assembly. As a result, they create special challenges to both quality and long term reliability. TO KILL A CIRCUIT BOARD: PERILS IN MANUAL SOLDERING & CLEANING PROCESSES Cheryl Tulkoff, ASQ CRE DfR Solutions Austin, TX USA
Today I Will Show You How To: Implement Process Control at Bench Top Cleaning Perform Localized Cleaning Reduce Solvent Usage Minimize Cleaning Labor Reduce Worker Exposure to Chemistry Improve Cleanliness
MANUAL CLEANING AT THE BENCH If flux residues must be removed manually, a four step process of wet, scrub, rinse, and dry is recommended. Use some form of dispensing system for the solvent to control the flow and volume. Ensure that the material is fresh and pure each time and never sits in a typical dispense or spray bottle since those bottles are rarely, if ever, cleaned. Brushes used in the process should be routinely replaced. TO KILL A CIRCUIT BOARD: PERILS IN MANUAL SOLDERING & CLEANING PROCESSES Cheryl Tulkoff, ASQ CRE DfR Solutions Austin, TX USA
WHY IS PROCESS CONTROL AT THE BENCH TOP VITALLY IMPORTANT TO PRODUCT RELIABILITY? Contamination is believed to be one of the primary drivers of field issues in electronics today. It induces corrosion and electrochemical migration or ECM. Contamination-related failures are frequently intermittent in nature. This intermittent behavior may manifest itself as no-fault-found (NFF) returns, is driven by selfhealing behavior and is, therefore, very difficult to diagnose. These failures are pervasive and have been observed on batteries, LCDs, PCBAs, wiring, switches, under coatings, over coatings, etc. The problem is expected to get worse as continued reductions in pitch between conductors makes future packaging more susceptible TO KILL A CIRCUIT BOARD: PERILS IN MANUAL SOLDERING & CLEANING PROCESSES Cheryl Tulkoff, ASQ CRE DfR Solutions Austin, TX USA
WHY IS PROCESS CONTROL AT THE BENCH TOP VITALLY IMPORTANT TO PRODUCT RELIABILITY? Contd. Increased use of leadless and bottom termination components (QFN, land grid array, etc.) results in a reduction in standoff height which reduces the efficiency of cleaning... Contaminants are concentrated under these low standoff devices. TO KILL A CIRCUIT BOARD: PERILS IN MANUAL SOLDERING & CLEANING PROCESSES Cheryl Tulkoff, ASQ CRE DfR Solutions Austin, TX USA
Localized Cleaning BACKGROUND Many electronics manufacturers add moisture-sensitive components to circuit boards after a water wash process. Hand-soldering these parts to a clean board demands a secondary cleaning process that is reliable, compatible with current chemistry, repeatable, efficient and safe! The same secondary cleaning process applies at all board level rework & repair areas. The fluxing process is critical, but often left to operators to determine quantity and application method. This is true also at rework bench tops. Because of the low viscosity of liquid fluxes, many manufacturers have moved to tacky fluxes for component addition and rework in an effort to prevent flux residue migration beyond the area of concern on a board.
Localized Cleaning contd. Localized cleaning is required to prevent solubilized flux migration. With the vast array of fluxes, coatings, labels, adhesives and other chemicals in use, help is needed to define solutions and recommend materials for specific cleaning applications.
Wet, Scrub, Rinse & Dry / Some Cleaning Methods: Using a Menda Bottle, Acid Brush and/or Scraping Tools is a Sloppy, Uncontrolled Process Solvent Becomes Contaminated Thorough Rinsing is Impossible! If You Can t Rinse, You Can t Clean!
Another Predominant Cleaning Method: Sloppy, Wasteful Operator Exposed to Chemistry/ Requires Fume Extraction Scrubbing Poor, Rinsing Great Very Expensive!
Better Process = Better Cleaning Wet Scrub Rinse Dry
The Trigger Grip Cleaning System A Unique Tool Enforces Best Process: Wet, Scrub, Rinse and Dry Saves Time Lowers Costs Improves Quality Offers Outstanding Reliability & Performance, Warranted 2 Years
The Trigger Grip Cleaning System is Key to Process Control Implementation Controls Amount and Flow of Solvent / Precise Dispensing Provides Means for Measuring Amount of Solvent / Process Control Definition Allows Brush & Syringe Attachments to be Defined for Specific Cleaning Tasks / Process Control Definition Localizes Cleaning to Rework or Component Addition Areas Allows Use of Modified Trigger Grip Cleaning Method to Further Minimize Contamination Migration
The TriggerGrip Cleaning System Attachments These Tools Are akey Part of the TriggerGrip cleaning System Brushes Or Syringe Tips Are Compression Fit And Slip Into Place Quickly And Easily Slo-flo Brushes Further Reduce Solvent Consumption and Help Localize Cleaning Brushes Are Sized For Large Or Small Cleaning Applications
MicroCare Electronics Products MicroCare Corporation 595 John Downey Drive New Britain, CT 06051 Office: (860) 515-3011 Toll Free: 800-638-0125 www.microcare.com