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Nov 13, 2017 | Determine the origin of the solder * Sloppy paste printing technique * Lax stencil underside cleaning practices * Sloppy misprint cleaning practices * Poor part placement practices creating solder balls * Poor material control allowing solder paste to dry-out * Aggressive reflow profile
Sep 19, 2017 | Steve, The 4 things I would do, and in this order: 1. Clean your stencil with stencil cleaner wipes after it comes out of the stencil cleaner. I like MicroCare ProClean (MCC-PROWR). I will even saturate the wipe with a bit of isopropal just till the wipe is damp, at least on the 1st pass. I wipe the bottom vigorously for 20-30 swipes forcing the solvent up through the apertures, then wipe the top once from left to right. If the wipe has any "dark" material at all on it i repeat the process till it does not. The stencil must be absolutely clean for these types of parts. Trusting in your the recommendations. 4. Nano coatings. If you need them, then you need them. You should at a minimum be using quality stencil squeegee blades that are coated. This is such an easy thing to do, and it makes a small difference. Sometimes a small difference is all you need to make an iffy print into a good print. I
Jan 25, 2017 | Our Stencil Mask Fiducial vanishes from black color to light where our Screenprint machine unable to detect fiducial during batch teaching (auto set-up alignment). Does anybody here encounter the same problem? I am searching for a dark marker or any material that cannot easily disappear after frequency of cleaning so that we can rework the mask fiducial by simply applying with the marker. thank you
Nov 18, 2016 | . We scraped off the majority of the paste with putty knives, then used the sprayer to blast the stencil with hot water. This dissolved the flux which allowed the solder to wash away. After a few going from the front of the stencil to the back a few timesthe stencil was completely clean. We would blast Lazy operators empowered by management. Sounds like you may have some nepotism? Since it falls to you to clean up someone else’s mess I have an idea for you. I once worked for a company that had a large wash sink with a hand sprayer very similar to what you would find in a restaurant’s kitchen of flux-paste or not. The downside is that someone has to periodically clean out the trap so that it does not fill up and let the solder down the drain. We had our maintenance department do it monthly. It makes it stupid easy for the operators, so it should be well received by your operators
Sep 30, 2016 | We sometimes have a misprint and we would never re-print on a board with paste on it already because it will surely get paste all over the bottom of your stencil and could smear between traces. If we do mispront we have to clean the paste off the board first but you can never get it all off and you
Apr 19, 2016 | Don't blame it on the poor paste thickness requirement [although I might go on to argue that it's could be a contributor to the issue]. Most likely you're the problem. About 70% of the time solder on gold fingers is caused by poor cleaning of screen printer, staging area (table), board support tooling, conveyor, and reflow oven chain or belt and keeping boards separate from the printer cleaning process. Other things to consider are: * Check the boards before starting the printing process. * Paste process. Are you pasting anywhere near the gold fingers? Are you leaching under the screen and contaminating the bottom side due to poor printer set up? Is your stencil under-wipe frequency proper? Is paste dropping from the squeegee blades onto the stencil? Could the paste near the edge be getting onto the conveyor? * Reflow process. Paste can splatter if your paste requirements don't match your
Sep 22, 2015 | We had 4 of these machines several years ago. If I remember right the drive that aligns the board to the stencil was stepper motors with no encoder feedback. We would see the same issue if our leadscrews and linear rails were not clean and properly lubricated. If they hung up or didn't drive
Dec 4, 2013 | Automated Stencil Washer Thank you for your reply Chris We have the same exact unit. But we've had issues with the cleaning solution leaching into the electrical cabinet and shorting out the PLC. They use a foam weather strip as the only insulation, and the cleaning solution erodes the adhesive, and causes it to come
Mar 5, 2013 | Here is "Compatibility Of Cleaning Agents With Nano-Coated Stencils" David Lober and Mike Bixenman, D.B.A., Kyzen Corporation: http://digital.trafalgarmedia.com/issue/46004/25
Feb 25, 2013 | of Sales & Marketing 770-807-4707 eric.moenatlaserjob.com My contact at FCTA is: Jeremy Glanzer, Marketing, 970-214-4854 jglanzeratfctassembly.com I believe that Kyzen wrote a white paper on cleaning coated stencils. BR, davef Oded: The coatings that I mention serve different purposes. * Antiadhesions seem to be designed to improve paste release from the stencil * Flux repellents seem to be aimed at reducing the under wipe frequency of stencils. At IPC APEX 2013, DEK and Aculon presented papers: * Big Ideas
Feb 7, 2013 | We also use the PPC-N29TP in both of our facilities. We've had both for over 6 years. Both have ha
May 17, 2012 | Underscreen cleaning cycles there are many reasons why FG and Nano are used and many papers written on them. Nano ssems to be the topic of interest right now. I agree it is mostly for printing fine and untra fine pitch. With that comes under stencil wiping to keep the stencil onto the board and not allowing paste to lift the stencil off contact. Chrys Shea of Shea Consulting gave a great paper at SMTA INt. in Dallas. I am not sure if this is allowed but I feel it maybe quicker. If you wish to have me send you more information and papers on this matter email me at
May 10, 2012 | We are having a lot of tomb stoning with this no clean solder paste. It's limited to larger, complex boards, affecting 0603 ferrite beads, capacitors and SOT23s. It was suggested that paste removed from a stencil should not be put back in it's original jar, mixing it with the new paste. Would love
Mar 4, 2012 | .(You cant set it up by circuit, so you must define a new inspector once for each circuit.) It cant see over pasting, only low solder. It has major issues with dust on a stencil during program load, as it re captures the stencils image every program load. If the stencil bottom is perfectly clean SMT Stencil Printer Recommendations , that will cut the scan time in 1/2 Also they are willing to license the version of hawkeye with over pasting inspection to owners of the better camera. Our biggest gripe with DEK is there blue under screen cleaner, The new paper rolls from DEK don't fit it, and it is constantly not cleaning because it thinks
Jan 5, 2011 | I am looking for a No-clean or water soluble solder paste, Sn63/Pb37 alloy, 15 - 25 microns (T5). I need to print with a 4.8 mil stencil opening. Does anyone know where I can get 250 to 500 grams in one week or less?
Nov 1, 2010 | Who Cares... Mix Away! Although you should not mix different Solder Pastes' together in a container or on a stencil (Mostly due to the flux, although solder sphere size and shape could cause an issue), mixing solder brands or chemistries on a board is fine... as long as you perform the proper steps prior to the addition of each type. (ex. Wash after Water Soluble - Prior to using No-Clean) Many companies use: Water Soluble Paste from Maufacturer # 1 No Clean Paste from Manufacturer # 2 Solid Wire from Manufacturer # 3 Cored Wire from Manufacturer # 4 You pick what works best regardless
Aug 19, 2010 | Solder Balls-No Clean Paste Are you reusing your paste or putting down new every time? I've seen solder balls before when operators try to use the paste past the recomended stencil life. I've also seen it happen with a bad batch of solder paste from a vendor.
Aug 17, 2010 | Solder Balls-No Clean Paste That reminds me...We already have home plate apertures on our stencil. Try number 2...I tried an overall reduction based on the copper layer of 10% and used oval apertures. I hope that you guys can suggest something that I am over looking. I know that once you get frustrated you start to over look
Sep 3, 2009 | with DCT250 (used in standard to clean stencils & misprints) residues gathering in ball shape - but we don't see any problem with profile temperatures we completed : - ionic contamination tests on a bare board compared with other supplier that has no problem (no evidence) we plan to do : - use different oven (more advanced & more zones) - clean one batch of pcb
Dec 29, 2008 | Watch out for workmanship specs. I don't believe this is covered under IPC-A-610. You may have to write your own. Alignment of the fixture and coplanarity of the bar and substrate are key. Also, pay close attention to stencil aperture and thickness design guidelines if using solder. The volume must be right to get good results. Cleanliness of the thermode is also important. Be prepared to remove and clean frequently.
Sep 23, 2008 | Do not wipe the board at first before putting it in your cleaner. It will leave more paste in your tank, but you won't smear it into every corner of your solder resist. We found that only our stencil cleaner would clean a board properly and leave no spheres behind. But again only if we did
Jan 23, 2008 | lens again (both sides) with a stencil wipe and alcohol....then use a dry one to clean the haze off. Good luck Here is a few things to try.... 1. Spin the z-shaft with your fingers and make sure it is smooth and easy to turn. 2. Check your handling in your profile for the part that the software is locking up on.......You cannot go any slower than 40% or this type of error can happen. 3. Clean the quadalign
Nov 9, 2007 | Best I can tell (Factory is in Mexico) is no solder from paste print. I'm ordering e-fab type stencils for them hoping to get better release. Also mandating they clean after each print, rotate their paste to keep it fresh, do LSM checks each hour for SPC check, Basic SMT 101 process control.
Aug 30, 2007 | Hi we are currently experiencing a problem with solder contamination of the gold contact pads on our pcbs following the reflow process, possibly through sputtering. We have been advise that this can be caused due to the pcbs being humid or due to the stencil not being completely clean. We
Jan 23, 2007 | Stencil cleaner If you are looking for an effective cleaning performance with long bath life and environmental friendly nature, then definitely VIGON SC200 is a very good choice...You would not regret it...If you want to try out, perhaps you can ask them for VIGON SC200 samples...This chemistry would definitely
Jul 3, 2006 | Dear mark This is Eyry Ren from Shenzhen comofaje Tech.co.,Ltd.We are the manufactucturer of SMT stencil clean rolls.If you have any problem please send mail to email@example.com. Our Engineer will give you a satisfying key
Apr 18, 2006 | we think about the 90 pounds], but we most likely use different style blades, units, or sumpin. We use depleted uranium blades. We begin at 1 pound per inch and then increase squeegee pressure just high enough to wipe the stencil clean. Isn't I-Source a stencil fabricator? So, what do they know Standard for Stencil printers edges pressure
Feb 1, 2006 | not get the clumps off your stencil, but also do a very good job of cleaning the stencils. Stencil and board Ultrasonic cleaner
Feb 1, 2006 | holding tank. It is large capacity handling stencils up to 40" x 32". Unlike models that use a straight spray clean method, the ultra-sonic type allows you to use the same water over and over again which reduces your outflow of hazardous waste. You can use water alone or you can combine with Smart Sonics Stencil and board Ultrasonic cleaner Hi Bruno, I am an equipment reseller in business since 1994. I have a Smart Sonic MG3000 ultra sonic stencil cleaner in inventory. It is a stainless steel model with Delta Sonics brand ultra sonic generator. It is the guillotine type that raises and lowers a stainless steel basket out of a
Jan 9, 2006 | I assume you're using a no clean Pb/Sn paste, with a metal squeegee. Here are some generic procedures for good printing results for all pastes. Clean and dry the stencil well using alcohol and vigorously rubbing it with lint free towels, blow it off with clean compressed air, put a new batch like to accelerate the warming process by setting the paste on the oven prior to use. Stir it for a few minutes by hand if it's in a jar. Run the stencil on contact with the pcb (no snap off), use 1b-2lb force per inch of stencil contact with the pcb. Set squeegee speed to 2-4 inches/second. You want
Dec 14, 2005 | right again grant, consider the fact that if you spend enough time inspecting the soldered boards/pre-oven and check the BGA solder paste pads before, and clean the stencil regularly and check solder paste dryness, check oven profiles then after checking maybe the first finished board for placement
Nov 10, 2005 | Solvent for stencil cleaning AJ: Problems with IPA are: * IPA / material being 'cleaned' combination still needs to be removed from the stencil. * IPA and empty containers are a hazardous material by RCRA criteria (40CFR 261) * Flash point (~12*C TCC) of IPA is low enough that all electrical equipment within a couple yards
Aug 25, 2005 | Stencil Cleaning / Zestron / Vigon I evaluated a couple of the Vigon products by Zestron last year and I think the SC200 was one of them. They seemed to clean OK, and Zestron said they were biodegradable, but they conveniently failed to disclose that they contained VOCs. If you are restricted on VOC emissions, I would confirm
Jul 14, 2005 | Considering all the constraints you are faced with, I would try changing the apatures for that part on the stencil. It seems as though a no-clean "homeplate" appature would put less paste on the board. Less paste means less flux, and it might be enough to prevent the tombstoning. I'm sure some
Jul 13, 2005 | Lead Free Stencil Design We do have solder balling on occasion but it is usually very minimal. When and if this becomes an issue with us we will then utilize the homeplate aperture. We do not wash boards as a general rule. All of our pb free has been no-clean. We can't find a good water soluble lead free yet.
Jun 28, 2005 | Are you saying that increasing the frequency of cleaning to every 3 boards *reduced* bridging, or that it's just something you tried? I don't understand why that would help(in my experience it has reduced "insufficient solder" conditions but not bridging). I would look at paste volume, i .e., stencil thickness, aperture size, or if you're printing off contact, and slumping (temperature or humidity).
Jun 13, 2005 | Devef, The stand off height is 75micron. We only clean the product after underfill process. Dispense epoxy under the FC & cure it before aqueous wash. Samples are sent for LPC (liquid particle count) Test to ensure cleaniness. By the way, our plant RH is 35 to 65 & temp about 23Deg C. The paste temperature on the stencil is about 25Deg C.
May 3, 2005 | cylicon. So, we clean 5K board with an Ultrasonic stencil cleaner with exactly the same standard product inside the tank and the result is perfect. Do you recommand this ??? If I have this problem in the futur I will do this process again. How are your results ??? Perfect What kind of liquid is used to dip them ??? we use SmartSonic 440-R SMT Detergent. This product is a standard product we use to clean stencils. I hope this help Frank R.
Mar 8, 2005 | Tim- You have two separate issues 1) Stencils and 2) wave. Stencils you can purchase a ultrasonic system that will remove the paste automatically or you can use stencil wipes to remove it manually. I would refrain from using towels and IPA as it dilutes the flux moreso than removing it. Scrape the excess solderpaste into a drum and wipe clean. 2) Wave dross floats.Scoop/spoon it off the top and put in a drum. Remember any siler looking material you put in the drum is wasted solder. I would try to seperate dross from solder with a perferated spoon. Also you could use solder saver (Kester
Feb 11, 2005 | am going to check the cleaning on the stencil, and we might check humidity, because it's Australia, so the air is dry, and this happened within a few days on two different products. We use Koki because have found it to be extremely good. Almost no residue, solders really well. It's always worked Hi, That's what I am thinking, and we might have a dirty stencils and cannot see the problem. We are going to get a magnifier, and check it out. I did not think the stencil could bur, but I didn't want to shoot the guys down when they had an idea on what it might be, so I thought I would ask. I
Feb 10, 2005 | . You need to invest in some type of a washer that uses pressurized fluid to blow through the apertures. It is IMPOSSIBLE to get a stencil totally clean by wiping. It is very possible that your release problem is due to residue on the aperture walls. (If you insist on the wipe method, get yourself . IE-inconsistent chemistries batch to batch. I would get on the phone immediately with your paste manufacturer. I have never in all my years seen a stainless stencil that was worn out. Maybe damaged, but not worn out. Another thing: I am still amazed to hear that people "wipe" their stencils off
Dec 17, 2004 | Earth Friendly Cleaning Chemical I agree, some will and some (most) won't. Your term "VOC free" was misleading. In any case, many of us have total VOC emissions to be concerned about and we cannot afford to bring in any additional VOC products. I even had to switch my stencil cleaner chemistry out because of "very low content."
Sep 30, 2004 | i have a 0.5 pitch(19x19 pbga array) ..with a pad of 20 mils (thou) , solder mask is same...(20th..)..and an stenCil aperture of rectangular 22 X 22.1 thou...WHICH SHOWS..I AM HAVING AN OVERPRINT..MY PASTE IS A NO-CLEAN.. COMMENTS PLS...
Jul 23, 2004 | Got to agree with John on this, get a stencil cleaning wipe something a little more potent than standard IPA and wipe the surface thoroughly, this should produce a green residue of solder resist. If this does happen then ask your PCB vendor to look at the extraction on the ovens as resist residue
Mar 9, 2004 | There is an article on our web site by Richard Clouthier, �SMT Stencil Cleaning: A Decision That Could Impact Production.� He talks about how high pressure sprays can damage the delicate land mass areas between fine-pitch apertures. High pressure air can cause the same damage. In addition, OSHA doesn�t like the idea of solder paste becoming airborne. Mr. Clouthier makes several points about stencil-cleaning that I do not see as part of this thread. A copy of the article can be found at:
Feb 23, 2004 | Solvent for a stencil printer I have an MPM SPM and two Ekra E4 screen printers. I have always run them dry with vacuum. I am also using no-clean paste and have not had a problem. The volume I run per day on the machines is 4 - 6,000 bds
Sep 29, 2003 | Hello everybody, We have a new product having a lot of open gold area. solder splashes during the reflow is a pain in the... Its an extremely small PCB and kapton taping is not an option. Stencil is at 10% reduction, Cleaning after every cycle. Reflow Ramp rate is < 1 deg C/sec. After a lot
Aug 27, 2003 | BMAN.........Consider yourself shot down. unfortunatly (for you) Mike and Ken are right on the mark. The root of your problem is the current system you have for stencil wash...Explain what Maintenance headaches you have. Many moons ago I had a Smart Sonic with an evaporator tank. This was by far the nastiest crap!! Our Maintenance team would draw straws to see who would be the lucky one to stick there head in and clean it. cal
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