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How to increase tolerances regarding co-planarity when using larger shield cans

Andersson, Niklas and Bengtsson, Henrik (2003)
Product Development
Abstract
The objective of this Master’s Thesis, entitled “How to increase tolerance regarding co-planarity when using larger shield cans”, is to find solutions for how to solder larger shield cans to the printed wired board (PWB) without losing shielding effectiveness. Advantages with larger shield cans, i.e. combining several smaller shield cans into one large with internal walls, are saved board space, easier assembly and lower handling costs. However, using larger shield cans increases the risk of co-planarity problems occurring. This will lead to unwanted gaps between the shield can and the PWB and difficulties creating a sufficient solder seam. A non-sufficient solder seam will in turn decrease the shielding effectiveness. The focus has been... (More)
The objective of this Master’s Thesis, entitled “How to increase tolerance regarding co-planarity when using larger shield cans”, is to find solutions for how to solder larger shield cans to the printed wired board (PWB) without losing shielding effectiveness. Advantages with larger shield cans, i.e. combining several smaller shield cans into one large with internal walls, are saved board space, easier assembly and lower handling costs. However, using larger shield cans increases the risk of co-planarity problems occurring. This will lead to unwanted gaps between the shield can and the PWB and difficulties creating a sufficient solder seam. A non-sufficient solder seam will in turn decrease the shielding effectiveness. The focus has been on solving the problem with co-planarity, either by solving the soldering problem regardless of co-planarity or by solving the co-planarity problem itself.
From interviews with employees at Sony Ericsson Mobile Communications AB and from the mission statement, statements and demands were derived which in turn formed the target specifications. A thorough literature study and interviews with employees at Lund Institute of Technology together with the statements and demands created a base from which a lot of concepts were created. These concepts were evaluated with help of criteria derived from the statements and demands. The best of the concepts were deeper investigated and some of them were tested in order to choose the best concepts. Two concepts were selected to be primary designed, “Solder pockets on shield can” and “Groove in the PWB”.
During the primary design phase, the two concepts were designed to be produced in a small prototype series. This design phase included complete measurements, material selection and tests. For easier inspection, the shield can was designed as a frame. “Solder pockets on shield can” were tested on a future mobile phone PWB and “Groove in the PWB” were tested on a prototype PWB developed only for this test.
The result shows that both “Solder pockets on shield can” and “Groove in the PWB” fulfil the objective of this Master’s Thesis. Even though the shield solutions are larger than the recommended maximum size of today, the shielding effectiveness are satisfactory. With only small modifications in the manufacturing, several advantages could be obtained. It is possible to use larger shield cans, which means fewer parts and lowered handling- and assembly costs. Also, the tolerance for co-planarity problems is increased together with saved board space. (Less)
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author
Andersson, Niklas and Bengtsson, Henrik
supervisor
organization
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
1514873
date added to LUP
2009-12-07 15:28:58
date last changed
2010-02-01 14:40:06
@misc{1514873,
  abstract     = {The objective of this Master’s Thesis, entitled “How to increase tolerance regarding co-planarity when using larger shield cans”, is to find solutions for how to solder larger shield cans to the printed wired board (PWB) without losing shielding effectiveness. Advantages with larger shield cans, i.e. combining several smaller shield cans into one large with internal walls, are saved board space, easier assembly and lower handling costs. However, using larger shield cans increases the risk of co-planarity problems occurring. This will lead to unwanted gaps between the shield can and the PWB and difficulties creating a sufficient solder seam. A non-sufficient solder seam will in turn decrease the shielding effectiveness. The focus has been on solving the problem with co-planarity, either by solving the soldering problem regardless of co-planarity or by solving the co-planarity problem itself.
From interviews with employees at Sony Ericsson Mobile Communications AB and from the mission statement, statements and demands were derived which in turn formed the target specifications. A thorough literature study and interviews with employees at Lund Institute of Technology together with the statements and demands created a base from which a lot of concepts were created. These concepts were evaluated with help of criteria derived from the statements and demands. The best of the concepts were deeper investigated and some of them were tested in order to choose the best concepts. Two concepts were selected to be primary designed, “Solder pockets on shield can” and “Groove in the PWB”.
During the primary design phase, the two concepts were designed to be produced in a small prototype series. This design phase included complete measurements, material selection and tests. For easier inspection, the shield can was designed as a frame. “Solder pockets on shield can” were tested on a future mobile phone PWB and “Groove in the PWB” were tested on a prototype PWB developed only for this test.
The result shows that both “Solder pockets on shield can” and “Groove in the PWB” fulfil the objective of this Master’s Thesis. Even though the shield solutions are larger than the recommended maximum size of today, the shielding effectiveness are satisfactory. With only small modifications in the manufacturing, several advantages could be obtained. It is possible to use larger shield cans, which means fewer parts and lowered handling- and assembly costs. Also, the tolerance for co-planarity problems is increased together with saved board space.},
  author       = {Andersson, Niklas and Bengtsson, Henrik},
  language     = {eng},
  note         = {Student Paper},
  title        = {How to increase tolerances regarding co-planarity when using larger shield cans},
  year         = {2003},
}