Screen printing transfers a material through a patterned screen onto a surface. In PCB work, similar printing terminology is also used for stencil-based solder paste deposition. The material and purpose determine the process; ink, solder mask and solder paste should not be treated as one interchangeable substance.
Identify what is being printed
Taiyo’s product documentation distinguishes solder mask products and legend inks, with product-specific application and curing methods. A printed reference designator and a protective mask layer serve different functions even when related equipment is used to apply them.
Solder paste deposition prepares selected component pads for assembly. Its subsequent processing is part of soldering, rather than simply curing a permanent graphic. Specify the exact material and follow its process instructions.
Control the image and registration
| Control point | Question to check |
|---|---|
| Pattern | Does the screen or stencil match the approved data? |
| Board support | Is the surface held in a repeatable position? |
| Alignment | Do printed features register to the intended targets? |
| Material condition | Is the material within its specified working conditions? |
| Finished deposit | Does coverage and definition meet the process requirement? |
Evaluate representative small features and crowded areas during setup. A large text label can print acceptably while a narrow feature elsewhere fails. The inspection sample should reflect the demanding parts of the actual pattern.
Separate printing defects from later defects
Inspect the deposit before the next operation where practical. Misregistration, incomplete coverage and unwanted spreading can originate during printing. Damage or appearance changes after subsequent processing may have a different cause.
Record the material identity, pattern revision and setup conditions when investigating a problem. Change one relevant variable at a time and compare the same features. Avoid assuming that more pressure or more material will correct every incomplete print.
Retain photographs of both the initial deposit and final processed result. That record helps distinguish a printing adjustment from a change needed in the subsequent processing stage.
Choose the process for the required outcome
- Define the material and printed function.
- Review the product’s approved processing guidance.
- Prepare suitable tooling and board support.
- Inspect an initial deposit.
- Complete the specified subsequent process.
- Verify the final result before repeating the run.
Some PCB markings and coatings are applied by other methods. Request the finished requirement rather than insisting on screen printing when the application does not require it. For component assembly, the PCB stencil guide explains why paste aperture data and assembly requirements need their own review.
Move from reading to a build-ready project
Use the fabrication and assembly checklists to prepare drawings, production files and test requirements.
Open the DFM checklist