SURFACE MOUNT PROCESS
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    • THROUGH-HOLE ASSEMBLY - SELECTIVE SOLDERING
    • Cleaning 'No-Clean' flux residues and other contaminants
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  • FAQ
    • Solder paste handling
    • Type 3 or Type 4 Solder Paste
    • Cleaning a misprinted PCB
    • Solder Paste Quality Control
    • What factors affect solder paste transfer efficiency
    • What stencil thickness should be used?
    • What is the difference between aspect ratio and area ratio of stencil apertures?
    • What squeegee speed should be used?
    • What squeegee pressure should be used?
    • What the differences between 'on-contact' printing and 'gap' printing?
    • What separation speed to use in solder paste printing?
    • What are the benefits / challenges of using halogen-free solder paste?
    • What is the best stencil aperture shape for solder paste transfer efficiency?
    • PCB delamination during reflow
    • What are the different types of reflow profile?
    • ROSE (Resistivity of Solvent Extract) testing
    • How do you validate a PCBA cleaning process?
    • Why clean a pcba that has been soldered using no-clean flux
    • How do engineered cleaning fluids such as Zestron and Kyzen work
    • How do engineered cleaning fluids affect surface tension and wetting angle?
    • How does the pH level affect engineered cleaning fluids?
    • How do mixed-bed and carbon filters work in PCB cleaning systems?
    • What are the risks of using ultrasonics to clean PCBA's?
    • What are the differences between 'Water-soluble' and 'No-clean' flux?
    • What is the difference between ionic and non-ionic contamination?
    • What causes electrochemical migration (ECM)?
    • What are methods of masking before conformal coating?
    • How to apply conformal coating by brushing?
    • How to apply conformal coating using dipping?
    • How to apply conformal coating using spray/aerosol?
    • How do selective robots apply conformal coating?
    • What is the best method to dry/cure conformal coating?
    • What concerns are there when demasking?
    • What should be checked when inspecting after conformal coating?
    • How to check the adhesion of conformal coating?
    • Tape and Reel Packaging Standards
    • What is 'Package on Package' (POP)?
    • Stock control and component attrition
    • BOM Comparison Software
    • Comparison of SAC305 and SAC387 Lead-Free Solder Alloys
    • What is a 'Eutectic' solder alloy?
    • What does 'SMT' stand for?
    • What does the term voiding mean?
    • How is void percentage calculated?
    • How to reduce voids in QFN device ground connection?
    • Low temperature lead free solder paste
    • CAD EXTRACTION
    • How are PCB's manufactured?
    • What are the IPC standards that govern electronics manufacturing processes?
    • What are the differences between SMEMA and HERMES?
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Is there a quick way of comparing bills of material to find differences when up issuing an assembly?

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When an assembly is up issued there can be many reasons for the change - some of which will affect the surface mount process and some will not.

The component placement program is one aspect of the process that may need to change but only if necessary - the reason for the up issue may only be a tracking change in the PCB in which case there will be no difference to the placement program.

The type of changes could be:-

  • Part number change/addition/removal
  • Circuit board reference change/addition/removal

There are many ways of comparing documents and one in particular which is quick, easy and the software is free to download is called MELD - available to download here or link below:-

meld-3.16.2-win32.zip
File Size: 13391 kb
File Type: zip
Download File


The image below shows the software in use to find the differences listed above

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