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Apr 15, 2019 | is used when you cannot statistically measure something within reason. Such as verifying solder joint integrity from a new soldering iron. Or how well a new stencil washer cleans stencils for example. Hope that makes sense and answers the question.
May 23, 2018 | Stencil deformation patterns Those patterns are either: a) the stencil has recieved some streching stress - either being pushed on and dented by some obstruction, or b) has been worn thin and therefore streched as a result. This type of change to your foil may cause a slight shift of the image, but probably not much (under 1 mil). However, it may make it harder for the stencil to lie flat on the board, so it could lead to bleeding problems during printing. To reduce the occurance of this issues: a) Always have your operators check and insure the "setup" of the tooling/stencil prior to running - be sure the pcboard
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
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
May 17, 2012 | Underscreen cleaning cycles with fiber, so I would buy one laser cut stencil that performed about the way I was used to then the next from the same supplier would perform as well as an electroform. I couldn't figure out why. Then I bought an FG stencil based on the hype and was impressed with how it performed. What I didn't realize was that the laser type and foil type were confounded - since the FG foils only came fiber cut I didn't know whether its performance was due to the FG material, the laser type, or a combination of the two. With later stencil orders I was able to separate out the effects and see that the FG foil wasn't what gave
Jan 16, 2011 | setting etc Manual Stencil printer, cleaning of stencils ease, etc ? i am also looking for a professional consultant, who can guide us or provide us with reports. Thanks with Regards, leo
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
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
Aug 4, 2009 | Here's a few ideas: If it has one, make sure the flexible coupler set screws are tight. Replace the tactile switch (often these appear to work fine in I/O but do not work properly in production). Clean and oil the tactile plunger if it has one. Make sure upper and lower limit flags and sensors are in the correct positions. Try doing stencil height toward the back of sencil as sometimes more vibration occurs near the center during stencil height that can trip a touchy switch. Hope this helps you!
Apr 26, 2009 | process is staying in control. Third, we know we're printing correctly when: * Paste at least as big in diameter as your thumb is rolling across the stencil * Paste is filling the apertures * Squeegee pressure wipes the top of the stencil clean * Paste releases from the stencil * Paste is on the board in nice bricks * Bottom of the stencil is clean. Sometimes too little squeegee pressure will not form a good seal and can cause the paste to bleed under the stencil, resulting in solder shorts. Forth, this links to paste printing papers on Daan Terstegge's excellant jump site:
Jan 20, 2009 | MrDif: You don't add fresh paste to used paste? We add fresh paste to used paste on the stencil to replenish the paste consumed while printing boards, so that we maintain a nice thumb-size roll of paste. We change the used paste when we clean the stencil either: * End-of-production run ... OR * End
Dec 23, 2008 | with snap-off when manual printing. Just do better.] * Control temperature in the print area. One *C variation produces a substantial change in paste viscosity. * Clean the stencil 2 Thoughts on using two passes of solder paste on the stencil: You have to produce good print. How you go about that varies manual stencil print 2 passes We hear you talking two main issues: 1 Solder paste release 2 Thoughts on using two passes of solder paste on the stencil 1 Solder paste release * Check your aperture & aspect ratios [Search the fine SMTnet Archives for more] * Do a better job with snap-off [we know it's hard to do a good job
Sep 4, 2008 | Jim, There are several articles on Misprint cleaning at http://www.smartsonic.com/article.html including the "Stencil and Misprint Cleaning Handbook" by the IPC. Real Chunks, We have replaced several pneumatic stencil cleaners over the years that were using IPA and other flammable solvents and exploded even with the electronics remotely located. The ignition sparks don't always originate from the stencil cleaner electronics. In Richard Clouthiers article, "SMT Stencil Cleaning: A Decision That Could Impact Production
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 20, 2007 | horizontal heating instead of vertical over the top heating method. I need advise on a good Stencil printer, that�s easy to clean, and is not extremely complicated to reload stencils. Thanks! SMT BGA capable oven and stencil printer. I am looking for a new semi automatic Stencil printer, and reflow oven that is capable of doing double sided boards with BGA�s. We currently own a Manncorp 4500R stencil printer https://www.manncorp.com/4x00_stencil_printers/index.php?view=overview&auto=done, and a 3 upper 2 lower zone oven also
Nov 12, 2007 | You need to perform process a capability study prior to putting these controls into place. Cleaning a stencil after each pass will get ugly, solvent residues remaining in apertures etc. 2D inspection is good. Change paste every hour will get very expensive, normally it is around 4 hours, Check the paste data sheet. I have had good no cleans last 8 hours easily on 20 mil pitch. Time should not be used for validation of print process (LSM), both time (stencil life) and number of prints are key here. An aperture can clog on the next print after LSM reading, you have a defect and the process is in control technically. use the LSM to determine when and how often you clean stencil, add paste, etc... I would make sure date code and storage procedures are in place as well. To be honest, QFNs are very easy packages to process, you need to really determine what the defect is, it is either the paste
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
Sep 14, 2006 | ultrasonics to clean misprinted PCB's (unpopulated only). This system requires a separate rinse and dry system EMC also.This works fine. We use the spray in air systems to clean populated PCB's. Oh, by the way we use the same spray in air cleaners to wash adhesive stencils too. Stencil cleaners. I am a tool and process engineer responsible for the cleaning system at Siemens VDO in Huntsville, AL. I have been over this area for more than 8 years. We use EMC Cyberclean 3000RF spray in air cleaners with Zestron SC202 chemistry. At this facility we have BGA, Fine Pitch, 0603 and 0205
Aug 1, 2006 | -off distance is too small. * Temperature in your screen printer needs to stable. Paste suppliers say that 1*C change can affect paste viscosity by about 10%. * Paste needs to be worked * Paste needs to be at room temperature * Stencil needs to be clean. * Fast separtion speed is best [you have good vacuum We never changed any thing after moving to imm silver. "Poor release" (paste hanging-up in the stencil holes) could have three main (or combination of) causes: 1 Equipment * Proper aperture area ratio provide better release * Laser cut release better than chemical etched stencil 2 Process * Snap tooling to hold the PCB down, otherwise it will stick to the stencil] * Decrease print head speed to get the paste to stick to pads 3 Material * Solder paste viscosity is too high * Solder paste is too tacky * Solder paste particle size is too large * Some pastes stick more than others * Some flux
Jul 20, 2006 | washed, do not clean the underside of the stencil again. Switch off the underscreen cleaner. This contaminates the foil again which requires another wash. Talk to Qualitek about type 678 solder paste (UK number maybe). This is a low splatter paste with a UV tracer which was developed for such a problem. We had a similar problem with gold contact pads. Cleanliness is paramount. If you are using foil tensioning system, wash the foil in a stencil wash before use as the cardboard cassettes may be contaminated. Be very careful when loading into a frame for the slightest bead of solder paste. Once
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 firstname.lastname@example.org. Our Engineer will give you a satisfying key
Jan 9, 2006 | printer needs to stable. Paste suppliers say that 1*C change can affect paste viscosity by about 10%. * Paste needs to be worked * Paste needs to be at room temperature * Stencil needs to be clean. * Fast separtion speed is best [you have good vacuum tooling to hold the PCB down, otherwise it will stick "Poor release" (paste hanging-up in the stencil holes) could have three main (or combination of) causes: 1 Equipment * Proper aperture area ratio provide better release * Laser cut release better than chemical etched stencil 2 Process * Snap-off distance is too small. * Temperature in your screen to the stencil] * Decrease print head speed to get the paste to stick to gold pads 3 Material * Solder paste viscosity is too high * Solder paste is too tacky * Solder paste particle size is too large * Some pastes stick more than others * Some flux formulations are very sensitive to humidity
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
Oct 28, 2005 | ? Are you running "0" for a snap off? How often are you cleaning the bottom of the stencil? Is this problem on every board that goes across this machine? Keep in mind if it is a machine problem --it must happen all of the time then. This machine is smart enough to screw up just when it wants to. Hope Hello Since we have a few years experience with these printers we might be able to help. Is these problems always with the same components? Is this a new type of paste for you? Is there tape on the bottom of the stencil? And how much pressure do you have for down force on the squeege blades
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 15, 2005 | We have Kester 256 no-clean spec'd as an alternate paste. I bring some 256 in occasionally to make sure it still works as a backup. The last batch I brought in was bridging like crazy. Scraped it off the stencil, put our regular Alpha back down and the bridges went away. Haven't had this problem before. Kester suggested stencil aps, screen printer parameters, oven profiles and everything but their paste. Didn't check where the batch was mfg'd. Be curious to here if you find out anything.
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 The problems we saw had to due with the Flux I believe. We saw what I would call poor coelescence and the residues were very hard for us to clean with our Water only cleaner. I will not lie and say I worked on the process very much. Since we already had/have a great no-clean process
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.
Jun 12, 2005 | Paramjeet Singh Gill Flip chip with aqueous flux, that's interesting. * What is the stand-off from the board is your flip chip? * What machinery and materials do you use clean your boards? * How do determine the cleanliness of the board under the flip chip? On to your issue with solder balls : * Moisture in the air condenses on cool solder paste. What is the temperature of the paste that you use? * OA fluxes take on moisture. You mentioned limiting stencil life to 4 hours. What is temperature and humidity in your plant? * Solder balling is often related to paste volume versus solder pad size . What are the sizes of your stencil and the pads on the board.
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.
Apr 11, 2005 | For 1,27 mm Column Pitch, we set our process like this: - Stencil 0,20 mm If allowed also for other SMDs otherways some time 0,150 with step up stencil used only for CCGA area. - paste height min 0,175 mm - aperture 0,75 to 0,8 mm - paste volumes from 3000 to 7600 cubic mils (By Cyber or SVS 3D API) when column lenght are around 2,2 mm best volume range is from 4500 to 5500 cubic mils. Other details : Paste Type-3, on OSP, Clean Process. Quality yield very high. Regards GS
Mar 3, 2005 | Top 5 of No-clean Solder Paste We also use Indium NC-SMQ92J. We do the same as mentioned per Russ. We reduce apertures mostly on QFP's with pitch of 25 mil or less (we place down to 15 mil QFP). All other apertures we keep 1:1. We print resnet 0805 size with no problems. You might want to check your stencil design to make sure it meets aspect ratio requirements. We use 6 mil, 5mil, and 4 mil stencils; depends on how much we need to reduce apertures and still be within aspect or area ratio requirements. Gus
Feb 10, 2005 | Don't kid yourself, something has changed. * Worn stencils should produce better release and greater paste deposits than less worn stencils. * Consider inspecting the effectiveness of your cleaning process with a X10 magnifier. * Temperature in your screen printer needs to stable. Paste suppliers
Jan 7, 2005 | Stencil Cleaning Systems Tel: 1(818) 610-7900 E-mail: email@example.com Web: http://www.smartsonic.com How actually the process of Electrofoam Stencil? 3) There are several papers on the safety of cleaning PCBs and ICs using ultrasonic technology. The latest is in the October 2004 issue of SMT magazine by William Kenyon, "Why Not Ultrasonics?" Most of the studies have been performed by Dr. B.P. Richards of GEC Marconi and the EMPF Lab. Dr
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
Apr 20, 2004 | Cleaning of stencil You're correct, alcohol can cure or cause reactions in epoxies. While you're waiting for others to reply: * Read your glue supplier's application notes. They often discuss cleaning procedures and materials. * Consider searching the fine SMTnet Archives. For instance:
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
Dec 2, 2003 | reliably, and we are interested in going 0201 on it eventually. So I assume we would need under stencil cleaning features. We would also like to later upgrade to a cartridge at a later date. Do people have any thoughts on this. Is there any other recommendations of printers in our price range, or reasons Stencil Printers Hi, I know this must have been asked a lot of times, however I have a "which is the best stencil printer" question. We are on a limited budget of around US$90,000 and we need to get an inline fully automated stencil printer. We have been looking at the Ekra, and it looks ok. We need to do 0402
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
Jul 17, 2003 | these steps: 1.Clean the surafce of BGA by removing all the balls and flattening the surface with solder wick. 2.Apply flux paste on the surface. 3.Get a stencil for reballing 4.Align the stencil and reball the BGA 5.Reflow the BGA Sanjeev
Jun 2, 2003 | hello, everyone. splice tape and stencil clean wiper and various label, which cheap and top quality. if you have interest in reselling abroad, contact with me. name: rosy. email: star7483
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