00198574-01_Process_Foundation_DEK_Micron_EN - 第13页
4 Process Hardware 4.1 Board (Substrate) Process Foundation DEK Micron-Series 12/2017 13 4 Process Hardware The hardware used is dictated by the process design. This will specify the print material and the design of the …
3 Stencil Print
12 Process Foundation DEK Micron-Series 12/2017
4 Process Hardware
4.1 Board (Substrate)
Process Foundation DEK Micron-Series 12/2017 13
4 Process Hardware
The hardware used is dictated by the process design. This will specify the print material and the
design of the stencil, tooling, etc. Just as important as getting the design right is ensuring that the
resulting hardware is correctly used and maintained.
This objective reviews each of the main elements of process hardware and offers advice on their
use and maintenance. This includes:
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Board (Substrate)
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Print Material
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Tooling
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Squeegees
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Stencil
4.1 Board (Substrate)
1. Added Value
2. Bare board
3. Print
4. Place
5. Reflow
6. Test
Storage/ Unpacking
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Ideally boards should be stored in a temperature and humidity controlled environment
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Boards should be unpacked just in time for production
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Unpacking in small batches will further minimize the risk of contamination
Cleanliness and Condition
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Boards should be unpacked and handled in a clean area free form debris
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Reject boards if there are any noticeable fibres or dust on the board surface as these can
adhere to the underside of the stencil and block the apertures
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Check board for damage to its surface, edges and fiducials
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Check board for warpage. Warped boards can cause print problems – a possible solution is to
increase print pressure to flatten the board
Handling
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Boards should be handled by their edges and as little as possible
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Cotton gloves should be worn when handling boards
Labelling
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Bar code labels, stickers, etc. can create a print gap and affect the print quality and height
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Position labels away from components (especially fine pitch)
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If possible, apply labels after the printer stage
4 Process Hardware
4.1 Board (Substrate)
14 Process Foundation DEK Micron-Series 12/2017
Washed Board Procedure
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Check washed boards thoroughly to ensure that no stray solder particles remain either on the
surface or in via holes – this is especially important if there is to be no further cleaning after
reflow
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Consider creating a procedure for running washed boards: i.e. to run them together at the end
of the batch and use 100% inspection
Substrate Problems
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Uneven pad surface
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Solder resist too height
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Underside components restricts tooling
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Material in via holes (washed boards)
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Barcode labels
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Warping and stretch
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Chamfered edges
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Fiducial quality
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Colour changes, surface finish
Exercise
If excessive print volumes were observed in your production what problems might there be with the
boards that could be causing it?
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