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PCB cleaning | clean boards – electronic assemblies

8 factors to get the best results and succesfully clean boards – electronic assemblies

  1. Determine which part on the boards needs cleaning. The part which needs being cleaned drives the cleaning process. To determine this easily take this in consideration;
    • What is the source of circuit board contamination
    • Are there areas where cleaning flied can enter of is trapped?
    • Are there any components which can be affected by the PCB cleaning process?
    • Are there secondary post cleaning steps like wire bonding or coating?
    • Which level of energy is needed to penetrate, wet and flush away soil(s)?
    • What are the through put rates?
  2. Determine the chemical nature of the soil(s) which needs being cleaned?
    • Will the PCB cleaning agent remove the soil(s)
    • Check the Soil Classifcation; is
      • Highly Soluble in Cleaning Agent – easily cleaned
      • Soluble in Cleaning Agent – Time and Temperature are key factors
      • Marginally soluble in Cleaning Agent – Requires strong cleaning agents
  3. Processing Condition;
    • Soak and Hot Reflow profiles may oxidize and harden soils.
    • Multiple reflow conditions can be harden the soils before circuit board cleaning.
    • Baking soils before cleaning harden soils
  4. Bottom Terminated Components
    • When the Gap Heights less than 75µm will reduce soil levels and it is easier to clean
    • A low gap heights require stronger mechanical forces and longer cleaning time
  5. You need to keep in mind the Material Compatibility with the Engineering PCB cleaning agent.
    • Metallization’s may interact (react or corrode) with aggressive cleaning agents
    • Part markings can degrade from both cleaning agent and applied energy
    • Cleaning agent can entrap Non-hermetically sealed components
    • Key factors are cleaning time, cleaning concentration, temperature and impingement
    • Staking components, bonding and coatings may
  6. The PCB Cleaning Agent must be matched to the soil(s) you want to clean. When a soil is hard to clean you require a stronger cleaning agents. So when the cleaning agent is not matched perfectly you will not remove the soil. Key facts to make a match is concentration and temperature.
    Also keep in mind that soil can change the properties of the cleaning agent as they load. And Controlled losses (drag-out- is crucial for long tank life.
  7. Cleaning the Machine
    • To penetrate the low gaps you need to apply impingement energy
    • A function of applied impingement energy is Wash Time
    • Low gaps may not clean at low applied energy
    • You’re improving the cleaning rate when using High flow intermixed with strong impingement
  8. You need to Control the Process
    • Controlled additions of the cleaning agent and water will optimize the performance
    • Critical soil load is the point at which cleaning drops of
    • The steady state is the balance between lose and replenishment real time