The NC676 no-clean solder paste is a new generation halide-free, rosin-based chemistry designed to provide a previously unseen level of repeatability and consistency to the printing process. This paste offers an excellent open time, extended abandon time and good soldering activity with all surface finishes. NC676 meets or exceeds the requirements for ANSI/J-STD -004, -005 as well as all Bellcore test criteria for pastes. Residues left behind are clear and maintain a virtually indefinite pin probability life.
Material Safety Data Sheets (MSDS)
- Excellent print volume consistency with Surface (SAR) as low as 0.55
- No Hidden Halides - Completely halogen free by all test standards
- Non-hygroscopic formulation suitable for high RH areas
- Wide reflow window with good solderability on various printed circuit board surface finishes
- Unlimited pin probability and clear post-process residues
- Low voiding/high reliability composition
- Compatible in either Nitrogen or Air reflow
- SN63 – MP=183°C
- 62/36/2 – MP=179°C
- Automatic / Manual Printing
- Automatic / Manual Dispensing
- Type-3 and Type-4 standard
- Type-5 available upon request
- 500 gram jars or cartridges standard
- Enclosed print head systems
- Other packaging upon request
- 10CC and 30CC syringes
- Larger package sizes upon request
Stencil aperture design and stencil quality are major factors in achieving excellent print consistency with any no clean solder paste. SMT stencils for printed circuit boards are recommended for optimal print performance, and can be custom designed to minimize and improve the yields of any process. Some general stencil aperture design guidelines follow:
- Fine pitch components (<= 0 0.020”)
A 0.001” reduction (L & W) to minimize bridging and create proper gasketing between the stencil and SMT pad
- Discrete components
A 0.002” reduction (L & W) for water washable and a 0.002” reduction (L & W), with “U-shaped” home-plates, for no clean to minimize mid-chip solder beads.
|Solder Paste Bead Size:
- 2cm (~0.75”) on startup
- Add when bead < 1.4 cm (~0.5”)
- Metal, Slic™ blade preferred
- 60 degrees from horizontal
- 25 to 150 mm/sec. (1 to 6 in/sec)
- Adjust printer for a pull or print demand process
- 0.18-0.27 Kg/cm (squeegee length)
- Slic™ and Ultraslic™ SMT stencils should exceed >10 prints/wipe
|Stencil life / Environment:
- >8 hours
- 30+60% RH and 20º C – 25º C
Storage and Handling
- Cartridges should be stored tip down.
- Paste can be stored up to two weeks at room temperature.
- To prolong the shelf life of NC670, refrigerate between 5°C~10°C, (41°F~50°F). At this range the shelf life will exceed 8 months.
- NC670 should not be allowed to freeze.
- When refrigerated, no clean solder paste must be allowed to warm up to room temperature.
- Paste must be >=22°C, (~66°F) prior to applying to SMT stencil for processing.
- Working range of NL932 is between 22-32°C, (~66°F - 89.5°F).
- First-In-First-Out (FIFO) inventory management practices should be used with all no clean solder pastes.
A linear ramp of 0.7°C to 2.0°C C/second is suggested to gradually remove the solvents and other volatile components from the printed circuit boards in the no clean solder paste. This also helps in minimizing solder balls, beading and bridging from hot slump.
A linear ramp also helps minimize depletion of flux activity which can occur with excessive temperature, preheat times, and at very high reflow temperatures.
A profile with a soak between 200-210°C for less than 20 seconds can be used to reduce void formation on BGA and CSP devices. (Request FCTA’s profile guide to void reduction).
While a linear profile typically does not produce tombstoning, a short 10-20 second dwell prior to transitioning into the liquidus point of the solder, and minimizing the QR between soak and liquid temperatures will help minimize tombstoning if experienced.
A cooling rate of 2°C-3°C per second is typical for most SN62 and SN63 applications. These parameters should be utilized to insure a fine grain solder structure and minimal IMC layer.