Conformal Selective Wave Solder Carriers
Also known as Exclusion Fixtures, Exclusion Carriers, Exclusion Pallets or Selective Jigs
The continuing rise of surface mount technology and compliant pin (press pin) connectors
has greatly reduced the number of PTH (Pin Through Hole) connectors.
However Pin Through Hole technology remains the preferred method of fixing older style
connectors and many magnetic components. This in turn has led to a style of mixed
technology boards with some or all of the following characteristics :
- Densely populated
- Double sided
- Close pitched active SMT or thermally sensitive components which cannot be exposed to a wave
- A specification which bars or minimises the use of glue dot
- Pin through hole connectors – located close to previously re-flowed surface mount components
To wave solder these connections you need what we call a Conformal Selective Wave Solder Carrier (CSWSC)
This is a tooling pallet which has been designed to:
This is a tooling pallet which has been designed to :
- Enclose all or nearly all solder side SMT components.
- Expose some or all pin through hole (PTH) components.
- Selectively allow solder to flow around the pins by creating the largest possible through apertures.
- Mask thermally sensitive areas such as BGA lands.
- Mask through holes, and if desired ground plane areas and even screws or rivets.
- Direct the flow of solder by sculpting the solder side of the carrier to conform to the local board layout.
- Reduced production time
- Increased product quality
- Increased board density
- Reduced board bowing
- Increased fixture stability
- Elimination of the Glue Dot/Stencil, mini wave, or hand soldering processes.
- Elimination of shorts and thermally damaged components.
- More complex and thermally sensitive SMT devices can be populated on the solder side.
- Reduced stress related joint failures,and improved backplane and chassis cut-out alignment.
- Reduced board clamping requirements when compared to open style fixtures.
- Higher fixture costs
- Longer Procurement
- Exclusion fixtures normally cost around 50-200% more than “picture frame” fixtures.
- Turnaround times are typically 3-5 days rather than the usual 1-3.
To find out if your pcb (pwb) is suitable for this process please go to CSWSC Design Rules