Operation BWP Issue 2.pdf - 第18页
18 Issue 2, Nov 14 Incomplete Causes Missing Edge Causes Misalignment Causes Excess Print he ight Causes Comment [JS16]: Not enough paste in front of squeegee / in ProFlow Toolin g too high or missing Paste cold or dry S…
Issue 2, Nov 14
17
Objectives OP 9 - Identify common print defects
Reference: Fast track process recovery guide, part no. 158546
Although following the procedures in the operator manual carefully will prevent most print
defects there will be occasions during production when print defects occur.
It is important that the operator understands which areas under their control can have a
direct influence over the print quality and how to identify a defect and quickly rectify the
problem.
Preparation
Tick off each of the following items as you complete them:
Discuss with you instructor the specifications of an acceptable quality print (refer to
your companies guidelines if available)
Your instructor will discuss a series of common print defects and identify the likely
operational causes as detailed in the recovery guide
The Perfect Solder Print Causes
Good alignment
No gaps between board and stencil
Good board support
Good stencil support (ProFlow)
Good stencil (good design, undamaged, Clean)
Good material (condition, temp etc)
Correct parameter settings (match process design)
Demonstration
Shown below are some common solder print defects. Suggest some common
operational causes of these defects
Bridging Causes
Comment [JS15]: Solder Paste too
hot
Tooling too high or missing
Board warped
Misalignment
Stencil damaged
Damaged squeegees / ProFlow
18
Issue 2, Nov 14
Incomplete Causes
Missing Edge Causes
Misalignment Causes
Excess Print height Causes
Comment [JS16]: Not enough paste in front of
squeegee / in ProFlow
Tooling too high or missing
Paste cold or dry
Stencil blocked
Squeegees / ProFlow damaged
Comment [JS17]: Paste cold or dry (paste knead)
Stencil blocked
Tooling too high or missing
Comment [JS18]: Tooling too high or missing
Wrong stencil (check revision)
Fiducial damage on stencil
Poor board quality / different batch of boards
Comment [JS19]: Tooling missing
Paste temperature incorrect
Damaged squeegees / ProFlow blades
Damaged Stencil
Stencil surface not clean
Issue 2, Nov 14
19
Objectives BWP 9 – Recover from common print defects
Reference: Fast track process recovery guide, part no. 158546
Although following the best working practices will prevent most print defects there will be
occasions during production when print defects occur.
It is important that the operator understands which areas under their control can have a
direct influence over the print quality and how to identify a defect and quickly rectify the
problem.
Preparation
Review the list of common print defects and their causes
Demonstration
Your instructor will simulate a number of print defects on the machine
For each defect complete the table below. Use the fast track recovery guide to help
identify the cause and remedy
Defect
Cause
Remedy