Guide to Temperature Profiling for Wave, Reflow & Selective Soldering 29th October 2013
Bob Willis – Defect Database Coordinator
Your Delegate Webin...
Guide to Temperature Profiling for Wave, Reflow & Selective Soldering 29th October 2013
Bob Willis – Defect Database Coordinator
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Process of Reflow Soldering Product Size Product Mass Component Type Printed Board Construction Solder Paste Alloy Flux Types Solderability NPL Management Ltd - Commercial
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Temperature Profiling Examples
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Temperature Profiling Examples
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What is a Thermocouple?
Two different materials are welded together to form a junction/bead. The two wire are insulated from each other to stop intermittent contact and false readings. The two wires are then covered with an outer cover. 1-60 micro volts can be produced between the wires which is converted to a temperature reading. NPL Management Ltd - Commercial
Example Thermocouple
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Solid Sheath Thermocouple
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Thermocouple Guide
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Temperature Profiling Probes Soldered Probes Aluminium Foil Kapton Tape Epoxy Adhesive Contact Probes Obtain this and many more NPL reports from the Defect Database http://defectsdatabase.npl.co.uk NPL Management Ltd - Commercial
Temperature Profiling Probes
Survey conducted on the SMART Group web site. Results from 63 participants who voted during the survey NPL Management Ltd - Commercial
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Multilayer Design
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Multilayer Design
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Temperature Profiling Probe Position
BGA 361
Temperature Profiling Probe Position
BGA 361
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Temperature Profiling Probe Position
Temperature Profiling Probes
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Temperature Profiling Probes
Mounting thermocouple bead to component termination with high temperature solder is by far the best technique. First mount the lead and secure with Kapton tape. Then solder the bead to the termination. Its good practice to also secure other leads with high temp solder if the board will be used for double sided reflow profiling. NPL Management Ltd - Commercial
Temperature Profiling Probes
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Temperature Profiling Probes
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Temperature Profiling Probes
Care need to be taken that the thermocouple bead is in the solder joint and not on the surface. If the wires are twisted and touching this will also give false random readings during measurement NPL Management Ltd - Commercial
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Temperature Profiling Probes Select a printed circuit board for profiling and an area array component for testing. Select a thermocouple lead and place on the surface of the board. Hold the lead in position with Kapton tape. The bead is positioned on the centre pads. Solder the bead to a group of four pads with high temperature solder. Hold the component firmly and locate the row of balls leading to the centre position of the component. Remove the solder balls making sure that the area to be occupied by the thermocouple bead position is free Place the BGA on to the surface of the board making sure that it sits flat on the pads. If the component sits flat then remove it and flux the pads and replace the BGA Reflow the profile board, the flux will allow the solder balls to wet the pads and hold it in position. After initial reflow place adhesive around the four sides of the component and cure the adhesive. This will reduce the possibility of the component coming off the board even when reflowed up side down. NPL Management Ltd - Commercial
Temperature Profiling POP Package
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Temperature Profiling POP Package
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Reflow Soldering & Profiling
Produce a slot in the surface of the board so that a bottom mounted PoP will remain flat to the surface of the board. Add a slot to the top mounted package to allow the thermocouple to be mounted between the bottom and top packages
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Reflow Soldering & Profiling
Aluminium tape can be used to hold the thermocouple in position on the bottom and top package for accurate profile measurement
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Temperature Profiling Probes Thermocouple leads from the printed board assembly to the profiler should not be loose or flying as could catch and tangle on the conveyor, linked pin or centre board support mechanism
Thermocouple leads should be bundled together using a high temperature sleeving or, alternatively, Kapton tape may be used to secure the leads
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Wave Soldering Pre‐Heat Single Sided Board 1.6mm Paper
Wave Soldering Pre‐Heat Profile showing excessive drop in temperature prior to wave contact
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Reflow Soldering Lead‐Free
The three row connector can be demanding thermally during intrusive reflow. The connector body and pins have different thermal demands, these are indicated by the range of temperatures from red to blue. Making successful reflow joints to meet the IPC 610 specification is fairly easy but engineers need to consider all component temperature limits and circuit board design. Pins close to the body of a connector and pin at the centre of the body will be the last to reflow in a tin/lead or lead-free process NPL Management Ltd - Commercial
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Reflow Soldering Lead‐Free
Reflow results prior to optimising the profile for the connector and increasing the conveyor speed to improve product through put. Incomplete reflow of the solder paste is evident in the centre of the connector and on the inner row of pins NPL Management Ltd - Commercial
Reflow Soldering Lead‐Free
Optical image after reflow before optimisation of the profile and reduction of the delta T across the connector. The joint images from the edge to the centre show complete reflow and progressive limited reflow of the through hole pins due to the delta T and peak reflow temperature NPL Management Ltd - Commercial
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Reflow Soldering Lead‐Free Profiles
Profile taken using a KIC profiler on SN100C intrusive reflow trial boards. Reflow conducted in air on a BTU reflow oven NPL Management Ltd - Commercial
To show the animated graphs use a player from www.globfx.com
Vapour Phase Reflow at ACW
Reflow of SN100C solder paste requires either a 235 or 240o C boiling fluid for vapour phase reflow. A fluid boiling at 240o C was used by Peter Barton to solder PIHR boards at ACW, Wales. ACW are a contract services provided, successfully using vapour phase for tin/lead and lead‐ free reflow. Peter was using a Galden HS240 fluid in a ASCON VP6000 system NPL Management Ltd - Commercial
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Temperature Profiling
It is more complicated to profile a vapour phase system and not all profiler suppliers have a cases suitable to protect the unit NPL Management Ltd - Commercial
Vapour Phase Soldering Lead‐Free Profile
Profile taken using a ECD profiler on SN100C intrusive reflow trial boards. Reflow conducted in a vapour phase system at ACW in Wales with thermocouple mounted in three positions NPL Management Ltd - Commercial
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Soldering through hole terminations at 280oC & 320oC per alloy NPL Management Ltd - Commercial
Selective Soldering Profiles
6
5
4
3
Soldering Direction PCB Direction
2
1
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Selective Soldering Profiles
To run the animated graph you need a player from www.globfx.com/downloads/swfpoint/ NPL Management Ltd - Commercial
Profiling Lead-Free Hand Soldering
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Profiling Lead-Free Hand Soldering
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Profiling Lead-Free De-Soldering
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Temperature Profiling for Curing
Examples of coated boards after coating cure, also examples with too faster cure cycle well outside of the supplier recommendations for the ideal profile
Drying Oven/Cabinet/Enclosure
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Conformal Coating UV Inline Cure
In line curing systems can use mesh belt or pin transfer systems depending on the type of coating method and materials used in the production process
Conformal Coating Temperature Profile
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Acknowledgements
Alstom Power Conversion BTU Datapaq ECD Fujitsu KIC (Link Hamson) Loctite Multicore Roke Manor Research
Obtain this and many more NPL reports from the Defect Database http://defectsdatabase.npl.co.uk
NPL EI Free Technology Webinars/Workshops Cleanliness Assessment Using Solvent Extract & Ionic Extraction to Improve Reliability
3rd December 2013 How to Test and Qualify Packages with Scanning Acoustic Microscopy (SAM) 4th February 2014 Effectiveness of Baking to Remove Moisture from Between PCB Ground Planes 18th March 2014 Practical Failure Analysis in Electronics – How to Do It 14th May 2014 Solderability Assessment ‐ Testing, Ageing and Practical Impact on Assembly Yield 10th June 2014
www.npl.co.uk/ei NPL Management Ltd - Commercial
Visit our web site www.npl.co.uk/ei
Guide to Temperature Profiling for Wave, Reflow & Selective Soldering 29th October 2013