Wave soldering profiling

Develop your recipe wave soldering exactly as you developed your recipe for reflow soldering. The only difference is that instead of using your paste supplier's recommendations as the starting point, use your flux supplier's recommendations as a baseline.

Sldrng, Wave, Setup, Profile Preheating: The temperature of the board (component side) during preheating should go as quick as possible to 45 �C (with maximum slope of 2 �C/Sec) and just before soldering an temperature of 85 �C. Wetting time: The time between the moment of first contact (between the parts to be soldered) and the solder, and the moment that the solder in the joints starts solidifying. Dwell time: The time between the moment of first contact (between the parts to be soldered) and the solder, and the moment of last contact with the solder. (This time should be between 2 and 4 seconds.) Soldering time: The time between the board actually contacts the solder and the onset of solidification. (Dwell time + approximately. 5-10 Sec.) Solidification time: The time solder is getting solid on the bottom of the board. Cooling time: Forced cooling after soldering reduces the maximum temperature reached in the areas on the component side of the board. However, forced cooling directly after solder bath, may cause unequal contractions, which will initiate cracks and therefore not advised. If cooling down is needed because of the temperature from the carrier is rising to high, the best place will be before or in the lift itself.

Good luck

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Frank-In addition (Dave gave some good scoop) we use a Pyrex Glass board to run through the wave. This is useful as you can see through the board .....you can watch the flux coverage, preheat, and Wave (be it Chip, lamda, or??) as it goes through the process. I like it for the Wave part as it allows you to see how parallel the board is to the wave.

Lastly, I do not know what type of flux application station you are using but if it is not a sealed pressurized unit you may need to also monitor the chemistry ratio. Sorry to add stuff but it is part of that process you want to monitor.

Some good sites:

http://www.bobwillis.co.uk

http://www.smtinfo.net/Db/_Wave%20Soldering.html

www.empf.org

I hope this helps

Cal Driscoll Communications Test Design, Inc. www.CTDI.com

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Frank,

ECD (WaveRIDER) and Datapaq (Optimiser) have wave solder machine process control devices. They will check the following:

1. Conveyor speed 2. Preheat Temps 3. Solder Temps 4. Wave Dwell/Contact Times 5. Wave Heights 6. Waves Parallelism

Go to http://www.ecd.com or www.datapaq.com

If your profiler is an ECD SMG, the investment for their wave machine gizmo is shorter money than DQ.

Happy waving!

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Hi,

All seem good answers and food for thought. Additions you probably know.

Flux Supplier Application Notes/Data Sheet. Many of them have run experiments to tell you what works for their flux on various machines. They might even give you options you can use for an experimental matrix (DOE is the usa popular phrase)

The Solder Pot Supplier's Application Notes.

YiEngr, MA/NY DDave

This message was posted the Electronics Forum @

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Frank- Dreamsniper touched on something I totally forgot about....DROSS.....This is a subtle way for $$$$ to be lost.

If it is silver and Shiney...it does not belong in the dross recycle bin. That is good Solder being tossed.

You can also add into the process reclaimation.

Cal

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Rules of thumb :-

1. Never over flux - not necessary and waste's money. Never top flux neither 2. Top Board temp. around 70C - 105C or there about's pending what laminate you use. Obviously the more flux you apply the higher heat required/denser PCB more heat etc. 3. As temperature is not really that super critical for most new fluxes it is extremely important the wave is level across and the correct dwell time. If unlevel wave, bridges will occur with a noticeable build up of flux down edge of low side of wave. If dwell time too low then flux build up on back edge of PCB and bridges across PCB. 4. Watch out for waxy, greasy residue's this is not flux related to new no residue fluxes and a red herring to a board issue with resist's extremely common. 5. Dont blame blow holes on plating - look at HASL flux contamination as this is commonly the cause but rarely blamed. The tools we use for wave riding is a company called Circuit Master Design Ltd ProWave, actually produces 2 D picture of both chip and main wave along with dwell times/length brilliant bit of kit well recomend it.

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Correct preheating of the assembly is critical.

Check with your flux manufacturer regarding the recommended topside pcb temperature as it enters the first wave. It is important that this temperature be achieved without burning the flux on the bottom of the board. A topside tunnel, or perhaps even topside preheater, may be necessary in the case of large ground planes or multilayer boards.

Bear in mind that the amount of heat required to meet this temperature will increase as the flux gets thicker. Therefore be sure to maintain the flux within the recommended density as reommended by the manufacturer.

Also, as the solder builds up in contaminates its melting temperature, and therefore its flow characteristics, change. Have your solder analyzed on a regular schedule.

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Frank, Your initial question about temperature profiling is a critical point to a good wave solder process. Especially if you have a No Clean flux. As recommended by many in the thread above, get the Process Data Sheet for your flux (this is not the MSDS). There will be a recommendation range for topside temperature on the sheet. ( eg. 190f to 220f, depending on the flux) Attach the thermocouples at different areas on the topside (pick areas of low, average and high thermal mass). Adjust temperatures of the preheats such that the average mass areas fall within the middle of the range and the low and high mass areas are still within the range limits. If you have smt on the board, make sure you follow the same recommendations for your smt components for temp rise. Most places settle somewhere between 2-3 deg c/sec. check your component specs. (you may have to play with the preheats along with the conveyor speed ). What flux are you using? Are your boards HASL or OSP? How are you applying the flux? The above 3 questions will have an impact on further recommendations to hone in the process. I have a wave solder process sheet that assumes spray fluxing. It lists solder problems with possible causes by likelihood. It may be in the SMTnet archives or you can contact me to email it. best of luck. vwhipple@sono-tek.com Vince

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Is this thread still live? The starting post date is from last year. Frank, you still there?? Vince W

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Just a thought....

Some Fluxes require temperatures upto 260F (127C).

Are you using water based flux or solvent (alcohol). I have noticed that many wave machines are NOT capable of preheating adequately when using water based materials. This can be compounded with selective pallets.

Wave dwell can be limited by flux selection. NC flux tend to have shorter dewll times (2-3 sec) where as OA's can survive out to 4+ seconds.

Is your flux dual wave capable. Low/Ultra-low solids NC's tend to NOT be dual wave capable. You'll know it by the icicle's and solder flags.

What alloy are you using? I think everyone is assuming Tin/Lead. All the above will be different with LF.

Oh, and finally you will find that wave flux can have a very large process window (especially high solids OA). NC's tend to be smaller requiring tighter process control.

I have one product that uses a high solids OA. Spec sheet calls out 190-220F target preheat temp. This 7lb, .200 thick backplane reaches a preheat temp of 300F. Solders like a dream! Keep in mind that your start point is the specification, but ultimately you will need to determine you process window in YOUR process.

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woow, looks like I need to go back on the road... you all have great info. but what happen to asking what type of machine do they currently use, what is the configuration of the machine, what type of flux are we using, are running single sided or double... man ol man....some of our helpers need to slow down, take a few more years to understand and then give advise... if you email me direct I will send you a powerpoint presentation that will answer all your needs free, not to all of you, just this poor soul... have a good one, oh and by the way, been doing wave as a sr. process engineer and consultant for 25 yrs. and supported one of the largest manufacturers of wave and reflow in the world... just a little food for thought, but not that I am beyond learning from all... have a good one..hope to help

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