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Nov 7, 2017 | If no-clean flux is reflowed correctly, many of the activators are encapsulated within the resin residue left behind after reflow. An ionic contamination test cannot differentiate between ionic residue that was encapsulated (not harmful) and residues that were not encapsulated (harmful). Keep in mind however, when no-clean flux is used and in cases when no-clean flux is actually not cleaned (today more than 50% of no-clean is cleaned), nothing is removed from the assembly. When assemblies are cleaned, it's not just flux that's removed. All process residues are removed (board and component fabrication residues as well as human and assembly residues). The totality of residues (process and flux) are increasingly harmful to an assembly. Even though ionic contamination testing may not discern between harmful and non-harmful residues, it still may provide value. I hope this helps. Mike Konrad
Nov 3, 2017 | Testing effect of non-clean flux residue on solder joints On your question about reliability ... " Is there testing we can do (environmental stress chambers) with which we can see the long-term effects of flux residue on solder joints?" Sure, incompletely activated low residue flux residues are potentially corrosive, just like poorly cleaned, cleanable flux.
Mar 27, 2017 | Just 2 cents, lead free flux residue is no clean?, how about leaded flux? how much flux residue it leaves on both types? is there a clean up procedure after wave solder? or is there a wave solder process?
Mar 20, 2017 | Testing effect of non-clean flux residue on solder joints We're currently using no-clean flux (SR-12) in a no-clean manual soldering process. The brownish flux residue impedes direct visual inspection of the solder joints. Therefore, we're forced to clean the residue off. (1) Is there testing we can do (environmental stress chambers) with which we can see the long-term effects of flux residue on solder joints? (2) Has anyone else seen this problem with no-clean flux residue and how do you handle it?
Jul 29, 2016 | Flux Residues on Wave Soldered PCBAs "ALPHA® EF-2210 is VOC-free, halide-free, rosin/resin-free, low solids no-clean flux which provides the highest activity of any VOC-free Bellcore SIR compliant flux for defect-free soldering. "[2016 Alpha Assembly Solutions] I assume that you're talking about flux residues that are different from the flux resides that all yall expect to see when soldering with a no-clean flux. If so, it's not straight forward to determine that material compatibility is the cause of your residue. Here's what you need ... "IPC-9203 Makes it Easier for Users to Determine Materials Compatibility." [www.ipc.org/9203]
Jan 8, 2016 | Flux residues found after assembly process (Clean process) To all the experts, Is there any equipment (like coating uv lamp) that can detect flux residues on the pcba?
Apr 15, 2014 | Cleaning old built up flux residues from reflow oven "the sprite sugar/water mix" becomes a solvent because the number of carbon molecules in the sugar chain is greater than number of carbon molecules in the flux residue chain. Er, something like that ...
Apr 11, 2014 | Cleaning old built up flux residues from reflow oven Have an older reflow oven which I need to clean up collected flux residues from the chain, mesh, intake/exhaust areas, slides etc heavy brown dust, likely water soluble residues, lots of polymerized brown resin as well.
Sep 23, 2013 | No-Clean flux residue from Secondary Ops New pcba supplier sent us first article pcbas (SMT, Wave & hand solder operations) that failed our testing due to no-clean flux residues found under ICs and around passive capacitors. Second lot came in and had 100% pass yield, but we still see a clear residue around IC and caps due to secondary hand solder operation. What is long term risk of this residue? We have done some HALT testing (via humidity testing) with no negative results, but are concerned about long term failures that may result from the residue.
Aug 4, 2011 | No need to clean unless the sticky residue is an issue for you. If you are working with RF, it could be an issue. You may have probe contact problems as well with ICT and FT fixtures. We use a low residue flux for our wave solder machines (Kester 977). Need to clean no-clean flux?
Jul 6, 2010 | Sean, We suggest having the PCB tested for ionic cleanliness. It is conceivable that though the visible flux residue has been cleaned, there is still invisible, yet ionically significant residue in the area of the board/part. We also suggest ensuring that the issue is not one of trapped flux residues underneath the body of the crystal, which could be shadowed in a cleaning process. And, yes, we have experienced issues with no-clean flux residues affecting the operation of the circuit. cheers ..rob
Mar 19, 2010 | No clean pastes leave more flux residues. These can result in void formation and inhibtion of underfill curing. Selection of an underfill that is compatible with the flux residue is important. One company that has written about the effect of flux residues on underfill is Zymet.
Nov 21, 2009 | Dave, I would only agree with you when you talk about low residue (water based) fluxes. In low residue (alcohol based) fluxes you can use non water soluble acids, so in the event you still have flux residues on the board water has no effect on them. And I assume with OA you mean water -soluble flux. These residues can do damage to the boards even without elevated humidity, these acids are all hydroscopic by nature and have to be removed from the board. Have a great weekend, Patrick
Aug 24, 2009 | not react with solder alloy. If is possible, give small amount of flux on PCB, or modify your fluxing method. In princip all resudues could by with mositure conductive. In a perfect soldering, all of flux react with solder alloy, but in normal condition are flux residues normal. Try to residues in n-2-ol Hi Joane, this flux is primarily designed for wave soldering. I think that manual soldering it´s possible. Certainly it´s very hard to dispensing correct amount of the flux. Succinic acid is one from all ingredients of this flux. If you have this acid on the final PCB, this mean, that all flux
Aug 23, 2009 | Hi All, Recently, I need to deal with a customer complaint that specify the PCBA white residue (flux residue from ecofree 303) may be the reason why the board intermittent. Anyone have such experience with this flux? Anyone can tell me is this flux corrosive and conductive?
Aug 20, 2009 | Armando: We're guessing that the white residue is on the laminate also. We believe that the residue has something to do with your low residue flux and water. It could be: * Water contamination in the flux. * Poor selection of preheat temperature that does not fully vaporize water in the flux Problem with flux
Aug 20, 2009 | Problem with flux Questions are: * On what portion of the second side of the board [eg, solder only, solder mask only, etc] do you see this white hazy residue? * Could you attach a picture? * You mention cleaning this residue. What have you used to clean the residue?
Aug 18, 2009 | Vapor batch cleaning of flux residues We are looking for suppliers of liquid vapor degreaser batch equipment for flux residue cleaning of PCB’s. Any recommendations? Thanks
Jul 31, 2009 | Flux residue Dear Sean Contrary to believe MOST formulators of No Clean fluxes or No Residue fluxes use organic acides that are in fact weak and benign. IF the residue was left on the board and you had a condensing atmosphere then you may see some issue with falling SIR values, but generally not electromigration. UNLESS the resiue left was a Halide containing residue (not No Clean) then you may see electromigration or much poorer SIR values. So the residue appears some time after. Is the PCB visibly wet after wave? Do you see a waxy/greasy residue as it could be that we are seeing the porous resist
Jul 28, 2009 | Flux residue Hi Sean, No-clean flux does leave a residue. Under the best conditions, it is invisible. There are many factors that can cause the residue to become visible such as an inadequate oven profile (or lack of proper preheat on a wave). Also, if wave soldering, the flux application method effects the amount of visible and invisible residues on an assembly. Lead-free processes, with their higher reflow temperatures also contribute to residues as the flux polymerizes (crosslinks) during the reflow process and no longer encapsulates metal salts. There are also environmental factors that can cause
Jul 28, 2009 | Flux residue Hi All, I have some question about flux residue resulted from non clean process as following: 1) Under what kind of circumstances that flux residue could appear? This residue does not happen during production but did appear after some period of time leaving factory. 2) How to clean this type of flux residue? 3) Is there any potentially that our wave machine parameter setting not optimized that could cause this flux residue appearance? If yes, which wave machine parameter setting that we should look into? 4)Is there any functional impact on the board if there is flux residue appear on its
Feb 3, 2009 | No-clean, water-based flux residues after wave... The spec for all PCB suppliers is "solder mask over bare copper using LPI on external layers (green)". The flux we use is No clean 270WR flux (AIM). As far as process parameters, like I mentioned before, same parameters for several suppliers, only one shows more flux residues (or solder mask reaction to the flux as Stephen said)... Regards, George
Feb 2, 2009 | No-clean, water-based flux residues after wave... What flux are you using? We use a low-solids No-Clean water-based flux. Maybe some of what you are seeing is not residue from the flux but is from reaction with the solder mask.
Sep 2, 2008 | if two boards with different solder masks give different results on flux residue level after soldering with the exact same machine settings than it is clear that one of the solder masks is not compatible with your no-clean flux. could be the solder mask is not cured sufficiently and parts of it interact with the solvent(s) of your flux. this types of residue is hard to wipe or clean off the boards. it looks like they are 'baked' inside the solder mask. use the solder mask that works. no clean flux + wave soldering issue
Aug 28, 2008 | Matt solder mask finishes gives the widest process window in view of potential amount of residues when using No-Clean. Shiny (glass like) finishes are more sensitive to residues due to lower surface area compared to matt finish. If the shiny finish is creating the shorts it might be that your flux is de-wetting on that particular surface creating: Flux concentrations = residue Place with no- or not enough flux = shorts To solder successful with no-clean you will depend a lot more on machine settings compared to high activity (must wash) fluxes. Again your flux manufacturer should have no clean flux + wave soldering issue
Aug 28, 2008 | formulated to be used �as is�. To maintain the right activity level you need to check with the flux manufacturer for the acceptable density range and make sure that you use temperature compensation. Increased density means more solids and will increase the residue potential on the boards. Lower density will lower solid content, but will also lower the flux activity level resulting in the shorts you see. If you can't find the right balance between residues and activity level with your current flux you might want to do a search for a flux that give you the best of both worlds. Google �No-Residue flux� no clean flux + wave soldering issue
Jun 26, 2008 | Water will not remove no clean flux residues because they are not water soluble. Solder paste with no clean flux should only be used when the assemblies do not need to be cleaned. That said, you can buy special cleaning solvents specifically for removing no clean flux residues if you must clean the assemblies and are stuck using the no clean paste. The better way to go if you need a clean assembly is to use solder paste that has water soluble flux in it.
May 31, 2008 | physically lift board of after fluxing to visually see what is covered, or using thermal fax paper to get to see coverage works well. PROPER low residue or no residue fluxes leave benign insulating residue behind not corrosive.
May 26, 2008 | What steps are taken in low residue wave soldering to assure the proper amount of flux is applied prior to soldering? * Too little flux can result in poor solder flow. * Too much flux can result in corrosive residues left on the board after soldering.
May 26, 2008 | It's possible that the flux residues from the solder paste used in your SMT process is not compatible with your water wash process. For instance, some no-clean fluxes leave resudues that are not water washable. When these residues are washed, they develop a milky white coating on the solder White residues
Mar 20, 2008 | Why are you planning to clean low residue flux? There are cleanable low residue fluxes, but why would you wan to clean it?
Dec 11, 2007 | Selective soldering: sprayed flux residues Hi everybody, Is there any criteria as far as No-clean flux residues surrounding solder joints when using selective solder machines? I have a Novastar SPA 400 and use flux NC kester 959. If I decrease the amount of flux, then I experience problems with poor solder fillet. Any feedback is greatly
Oct 11, 2007 | We'd probably hand solder these coils with low residue fluxed wire solder, after cleaning. Coils and Water Soluble Fluxes
Sep 13, 2007 | residue * Flux, both water soluable and low residue * Soldering iron, one each for water soluable and low residue * Sponge, one each for water soluable and low residue * Cleaning procedure Cleanliness: Cross Contamination of Flux After receiving either a water soluable or low residue soldered board for rework, in a real life work environment, regardless of the quality of the documentation, we can picture it a bit confusing for troop to consistantly select the proper combination of: * Wire solder, both water soluable and low
Jun 6, 2007 | Is your NC flux residue cleanable? What does your flux suppler recommend?
May 16, 2007 | Is the frame turning white or is it the flux residue? What kind of flux, WS or NC?
Apr 23, 2007 | We agree with Grayman. You should clean your fixtures. If you apply [leave] low residue flux in amounts greater than the supplier recommendation, the remaining residue can cause damgerous corrosion. Certainly it is then no longer low residue.
Jan 18, 2007 | typical areas that flux residues pool up: 1.) Around chip components. 2.) Around fine pitch IC Leads.. 3.) The DPAK Heatsink area... etc.. Flux residues will also look... 1.) brown and gummy. 2.) flakey 3.) or gummy transparent.. Again it depends on the solder paste. Reduce flux If you are, in fact, running a No-Clean solder paste: Different no-clean solder pastes will leave different types of (benign) residues. If your paste has been qualified from a Bellcore/SIR/Electromigration standpoint, any residues remaining will NOT ever cause problems in the field...EVER! Some
Jan 8, 2007 | flux residue after HAL The water soluble flux residue is staying there because the rinsing temperature it may be too low. The flux needs about 130-140 degrees celcius to become soft. If you are using water soluble flux, as per IPC A 610 standards it needs to be remove completely from the assemblies. Hope this helps.
Dec 26, 2006 | flux residue after HAL What is the make-up of the residue? Is finding this residue new to your standard operation? What has changed?
Dec 20, 2006 | Flux residue cause high false reject at ICT We use a solvent called AK-225ATE (there is also AK-225T) that works great for removing RMA flux residue and no-clean flux residue. Info at http://www.AK-225.com
Dec 18, 2006 | Hi, Yes, I would hate to resort to cleaning, but the product must be clean. We have been using palettes to keep most of the flux off the PCB, but there is still residue around the connectors. Does anyone suggest a good no clean flux to use with lead free process that leave as little residue as possible? Also, what's the best solder mask type for minimum flux residue? Regards, Grant Wave flux and profiling
Dec 18, 2006 | Yikes!! In-line cleaning, to clean cosmetic and benign residues (from a NO-CLEAN) flux... You sure you can't switch fluxes? Another variable with residues is the solder mask. Depending on mask type (glossy, matte, semi-gloss, or semi-matte), will exhibit more or less visible residue. Wave flux and profiling
Dec 8, 2006 | Flux residue cause high false reject at ICT Try flux buster ICT pins.
Oct 31, 2006 | Flux residue cleaning procedure of the nearby BGA ... which is it? Next, the method for cleaning the white residue on the connector will depend on the composition of that material. You say that it is flux. What type of flux do you have on the connector? Finally, whenever we hear "white residue" and "flux" used in the same sentance, we think: "low residue flux and water". Together low residue flux and water cause the flux residue to go milky white. [Hint: IPA is 50% water.]
Oct 30, 2006 | Flux residue cleaning procedure thanks for your inputs,but what i meant was that a connector component beside the BGA for repair has some flux residue on its leads after baking, the BGA was Ok. we are wondering why this happened...pls enlightened us.
Aug 22, 2006 | Using no-clean flux going thru wave when comes out there is a bit of flux residue left on board. If wiped the residue shows a yellowish tint. Any ideas what this means how to get rid of it? yellow residue
Aug 1, 2006 | Does anybody knows if there is any reaction if I clean OA solder/flux residues using Isopropilic Alcohol? Is there any chemical recomended to clean residues manually instead of using a washing machine. Cleaning OA solder core residues with alcohol
Jun 20, 2006 | Low Flux Residue Solder Paste We evaluated four SAC305 pastes. Of the four, we found Alpha OM-338 to appear to have the least flux residue. We also found it to be the most dull, least shiny, most non-SnPb looking of the four.
Jun 20, 2006 | Low Flux Residue Solder Paste I'm using a lead free solder paste, low residue from SENJu among all the pastes I've tried it is the best I've found. you can ask for any type of alloy, but request the 729C flux type. kind regards
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