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May 22, 2018 | Stencil deformation patterns there are numerous factors: -stencil age -stencil finish and thickness -stencil-board vertical alignment -board support -squeegee pressure -squeegee blade material and condition question here is did stencil changed its dimension over time? are there any positions misprinted because of this ? on this images, it looks like there are warps at squeegee blade start, that could be caused by raising board too much, pressing it against stencil and warping it. i can clearly see blade start and board start. do step cycle and see is is there space between board and stencil after alignment. your problem
Apr 5, 2018 | Possible to mix a No-Clean solder and a Clean solder process We are currently in a Clean solder process (SMT+Wave Solder+Washing). Now our management is planning to convert to a No-Clean process in SMT due to limitations of solder availability and reduction of washing process. Question1: Is it possible to wash with DI water a board with No-clean solder ? Will it impact solder quality? Question2: Can we mix both clean and no clean process? SMT-No clean, Wave solder-clean Thanks hopefully can help me on this issue.
May 9, 2016 | Contamination of the cleaning agent From the SWA data sheet--"SWA is ideally suited for the removal of flux resides and many other cleaning applications that do not contain sensitive metals and substrates. Used for cleaning metals prior to plating operations to provide an extremely clean and slightly roughened surface, allowing excellent bonding of the plated material." From the SWAS data sheet--"SWAS is ideally suited for the removal of very stubborn flux resides and no-clean fluxes, which can be extremely difficult to remove." Based on the data sheet information, it appears you are using a far more aggressive cleaning solution
Oct 26, 2015 | We buy stencils from Stencils Unlimited (stencilsunlimited.com) which is the sister company to PCB unlimited. Stencils Unlimited will be the ones making the stencil if you order the pcbs with PCB Unlimited. We have never ordered pcbs from them so I can not speak to the quality of those. We have gotten good quality stencils and good customer support from Stencils Unlimited.
Jul 15, 2015 | Cleaning misprints with no-clean? I've read different views on this but the best results i've seen are from when the misprinted PCB is put directly into an automated 'spray-in-air' cleaning machine and cleaned using an appropriate cleaning chemical. Any attempt to manually clean the misprinted solder paste from the PCB usually results in solder paste being trapped in vias and in solder resist channels next to pads. http://www.surfacemountprocess.com/cleaning-a-misprinted-pcb.html
Nov 20, 2014 | stencil Hello, Can anybody tell me what is the life span of a stencil? How many stokes on the stencil is the maximum count to have PREDICTIVE maintenance on the stencil.Thanks
Mar 7, 2014 | Kapton Stencils for Prototyping Has anyone used a Kapton stencil for SMT prototyping? http://www.soldertools.net/kapton-stencil-5-mil/ Thanks BWET
Jul 30, 2011 | Need to clean no-clean flux? Do we need to clean after hand soldering with no-clean flux solder wire? I am just wondering. The flux is clearly visible. Will there be any long term negative effects on the modules? Is there any IPC requirement on cleaning it? BTW, I talk about normal resin based flux, not the water soluble type (which I think is not no-clean anyway)
Jul 19, 2011 | solder paste release from stencil Has anyone tried using a product thet when applied to a stencil, it facilitates the release of solder paste from the stencil, including the fine pitch openings. It makes the stencil's surface "fluxophobic". Same principle as Rain-X for windshield. Anyone?
Jun 27, 2011 | PCB Washing No Clean I fully agreed do not CLEAN the NON CLEAN process. However, some customer may request to clean the non clean process; and they willing to pay for it. In order to clean the non clean processes (the residual on the board), you need to consider the compatibility of your Non Clean chemical used . The best way were first understand your non clean chemical characteristic, then select some chemical cleaning supplier (you can get a lot of supplier from web search, I do not mentioned here as I am sale person from any of this company and do not tried to put wrong comment of certain cleaning product
Jun 24, 2011 | PCB Washing No Clean I am going to open the flood gates of comments. The purpose of no clean is so you do not have to clean it. Yes I am aware of no cleans that you can clean. If you need to clean the boards use a water soluble paste. If you do not clean, no clean properly you can cause even more contamination on the board. Now back in the day for you old timers cleaning boards was not a big deal with the old style vapor degreasers until we found out it was destroying the ozone layer.
Aug 21, 2010 | Plasma Cleaning / Etching Does anyone have any experience or heard of cleaning fully populated PCBs with plasma cleaning?
Jun 18, 2010 | Polyimide Stencil Vendors Stephen, Yes, stencils for individual components. I have located a few laser engraving business that make the stencils custom.I have contacted CircuitMedic to see if they make the stencils custom or not. thanks for your advise. I appreciate it.
Jun 18, 2010 | Polyimide Stencil Vendors Are you talking about mini stencils for individual components? If so we check here first http://www.circuitmedic.com/products/stencils.shtml I think circuit medic only has ones for parts they have done repair work for. Their selection is a bit unusual in that common patterns are not there but some uncommon ones are. If they don't have it then we get some from one of our local stencil shops that still make polyimide stencils. They make them the same as regular stencils except instead of putting them
Jul 23, 2009 | Stencil Fiducial Repair Hi PPM! Have your stencil house mark fid with laser machine - that how we use to have fid mark once it marked with laser it last very long time like stencil's life. Good luck! Steve USA STENCILS INC
Jul 17, 2009 | DEK Stencil image offset? just tell the stencil house, have it cut at center of front stencil. how about your DEK with auto stencil loading of manualy pull rod???
Nov 19, 2008 | Stencil Cutters As one stake in the ground, a good stencil shop needs to produce 20 to 30 stencils day in order to justify itself being around. Why does your boss want to consider getting into the stencil cutting business?
Oct 31, 2008 | stencil to pcb manufacturing tolerance Here is some more reading on stencils for you: http://www.smtinfo.net/Db/_Stencil%20Printing.html
Apr 17, 2008 | the pads when being lifted out of the solder pot. This is especially bad when used with Lead Free HASL finish due to temperature of dwell and time in pot. Trying prewiping the PCB with Stencil Cleaning Solvent to see if this removes the problem Hope it helps Greg
Feb 20, 2008 | Inspecting a new stencil We are in a situation where our parent company sends us stencils from Japan, but the Gerber is not sent. When we need a replacement stencil, we need to wait for Japan to send it. Can your stencilscan system reverse engineer the stencil and generate the Gerber?
Feb 18, 2008 | Inspecting a new stencil Print paste through the new stencil with a piece of mylar [or other clear plastic sheet about the thickness of paper] between the board and the stencil. Dispose of the mylar according to local practice after confirming proper aperturation of the stencil.
Oct 19, 2007 | Cleanning no clean residu Really, if you start out from the beginning planning to clean the boards, then DON'T use the no-clean flux! The way that stuff is made, it leaves a hard, low-solubility residue that takes a LOT of effort to get clean. If you plan to clean, use a water soluble flux, it will wash off with MUCH less effort. On some specific boards, we have used no-clean flux, but needed to clean just a couple components, and found it to be very hard to get it clean. Jon
Oct 19, 2007 | Cleanning no clean residu Hi Rob, I must take issue with your statement �By definition, no clean solder can be not-cleaned�. All no-clean fluxes can be cleaned. Whether or not one cleans no-clean depends on a variety of factors. More than eighty percent of all post reflow flux residues being cleaned today are no-clean . Although that sounds like a strange irony, there is a logical reason. While many applications do not require cleaning, some do. Many contract assemblers operate a no-clean line and just clean the assemblies that require cleaning due to customer, application, or environmental demands. Rather than running
Oct 19, 2007 | Cleanning no clean residu By definition, no clean solder can be not-cleaned. The solder/flux are formulated to result in low ionic-contamination, hence, no cleaning. I have, however, always had at least one customer that requests their no-clean solder get cleaned. No-clean solder is used post aqueous wash, for parts that are wash incompatible, but the customer wanted no visible residue. If this is your own product, you can prove out the efficiency of not cleaning the no-clean operations by a. conducting ionic contamination testing, and b. conducting accelerated life-cycle testing without cleaning the board
Jan 19, 2007 | Affordable, non-flammable cleaning solutions? For flux cleaning after rework try "ProClean" flux remover.
Oct 17, 2006 | Cleaning under LCC's Hi Steve, I agree with you that cleaning under LCC's is often difficult but its not impossible. In order to clean the residues, the most important thing to consider is the right compatibility of the fluxes with the cleaning chemistry. There are several companies who manufacturer cleaning agents especially for cleaning under low stand-offs. The high precision cleaning agents provided by companies such as Zestron, Petroferm, Kyzen do have the ability to fulfill your requirements. Since you mentioned that you are involved with Aerospace; it offcourse is much easier to change the chemistry as compared
Oct 2, 2006 | PCB Assy Cleaning Assuming: * Customer board has been designed to provide for cleaning under components. * Cleaning equipment is capable. In meeting J-STD-001, your current cleaning equipment should be able to clean: * Water washable fluxes. * Low residue fluxes, provided the flux is cleanable and you follow the flux manufacturer recommendations. Solvent systems often are used for cleaning rosin-based fluxes in hi-rel, military applications.
Oct 2, 2006 | PCB Assy Cleaning We have a customer enquiry that requires PCB assemblies to be cleaned to J-STD-001 / -004 class 3. We use both water based and no clean process chemistries. No clean flux residues are not permitted and would therefore have to be cleaned. My question is would our spray in air in line water wash or immertion aqueous wash be capable of cleaning to the required level or should we consider investing in a solvent based system.
Aug 24, 2006 | are running at hehe.
These solder balls are at the end of pad, which end? under the part or away from the part.
I believe you may have stencil issue myself, if profile is good.
common causes of balls are:
ramp rate too fast (splattering appearance)
print misaligned (splattering appearance)
bad paste either lot or type. (splattering or formed ball appearance)
bad stencil design (could be single ball or splatter)
poor paste handling and storage - excess moisture in paste
why are you worried anyway? after wash they should be gone since it is water soluble, if they are not gone then you also have a cleaning prob.
So get us the profile data such as max ramp slope, TAL, Max temp, and soak paramaters (how long at what temp)
Hope this helps, solder balls can be controlled we just need to see what you are doing.
( Jul 24, 2006 | - Dirty stencil transfering paste from the stencil bottom.
- Stencil opening (Pad Hole) to pad ratio incorrect - too large
Jul 24, 2006 | - Dirty stencil transfering paste from the stencil bottom. - Stencil opening (Pad Hole) to pad ratio incorrect - too large -misaligned stencil
Jun 20, 2006 | Hi, Yes, forget Guru, he's a "tosser" who talks "bolloks". Did you ever notice the English have fantastic words for putting people down? Anyway back to the original question. A manual stencil printer might be ok if your not doing anything too tricky on the technology side. However if your doing some 1 mm BGA's or any lead-less stuff, your going to need something better. However we had a manual stencil printer for about a year and it worked great. It was a US brand that had a bearing guide down the side, and we modified it with a metal blade, as it normally had rubber. It worked well. A , but they are a real problem, or expensive when you consider the cost of a good second hand oven. Check it's clean, so you know your not getting a used up junk oven. If it's clean, it should be ok. That should do you. Your doing just over the volume for this to be easy with any kind of equipment, so you do need
Feb 1, 2006 | Electric Arching on Y-Cap using No Clean Flux Your product may not no-clean compatible. "No Clean" must not be confused with "no need to clean". Your end application, operating environment and circuit operation (form-for-function) will dictate your cleaning requirements.
Dec 29, 2005 | Problems with space space saver stencils Has anyone else had problems with the space saver stencils and frames. The stencil tends to bow in the middle when clamped. These are the frames with only 2 pins to hold the stencil in place. Thanks for any advice
Dec 15, 2005 | my 2 cents here --- Even though the boards need not be cleaned after SMT when using no clean flux, you will still have to clean them before conformal coating.....and most solvents used to clean boards before coating will take out the no clean flux residues.
Oct 9, 2005 | Water Jet Stencil Cut There is a stencil cutting machine in the industry which utilizes a water jet to deliver a Laser beam for cutting stencils. There are no machines of this type in the states. The quality is no better than a Laser cut stencil using a good Laser System. LPKF is the best.
Aug 22, 2005 | Stencil manufacturer Photo-Stencil or SMT
Aug 10, 2005 | cleaning of no clean flux Comments are: * Sounds like it's necessary to clean "heareous F381, F352 no clean solder paste" in your application. Consider a paste that may be better suited to your application. * If you're cleaning "low residue flux", consider using an organic acid flux? OA fluxes are much easier and cheaper to clean than low res. * Other RF applications have avoided cleaning of low res fluxes. Flux suppliers say things like: -- This material has been utilized on various assemblies with RF designs without cleaning; however, the compatibility of flux residues on RF assemblies is strongly dependent upon
Jul 14, 2005 | Problems with frameless stencils on MPM?? The tactile sensor seems to be fine. I think it may have something to do with the stencil being not as tight as to one that is on a stainless steel frame. When we set the height of the stencil we have to do it towards the back of the stencil because of the aperatures.
Jul 13, 2005 | Problems with frameless stencils on MPM?? Does anyone else have problems with the frameless stencils on the MPM UP2500. I noticed after I do a stencil height adjustment it looks like the vacuum actually pulls the stencil to the board.
May 26, 2005 | how clean is clean? what test methods can be use to verify that the cleaning process for SMAs with water soluble paste is sufficient?
Mar 23, 2005 | Stencil Organization/Storage Hi Bob we have more than 130 stencil we , also use racks than old 25 stencil the printer program has the same value than the stencil. for example see dek.com for racks.
Mar 17, 2005 | your selections are representative of the finest and largest features on your stencil. Measure those 5 spots and get a standard deviation and average. Take your average and add 3x the standard deviation for the upper control limit and subtract 3x the standard deviation for your lower control limit responsibility is important. It's very easy to set super tight control limits but if operators are wiping / cleaning every board for a misprint, how effective is our process? regards, justin
Mar 7, 2005 | clean rooms/ wire bonding It depends on your product requirements. I have seen aluminium wire bonding operations in as high as class 100K clean rooms. These are the assembly areas for calculators. The best is class 10K clean room for wire bonding. You can go upto fine pitch wire bonding applications in a class 10K clean room. Once you establish class 10K, over time, the clean room condition will improve to about class 5K due to constant circulation of clean air. So you need to balance your product cost / profits with clean room conditions. Maintaining a class 10K or class 100 clean rooms is very expensive.
Jan 26, 2005 | Look here: http://www.pcbexpress.com/stencils/stencil_article_page1.htm
Jan 20, 2005 | no-clean flux removal esoderberg: So, why do you want to clean your no-clean flux residues?
Oct 29, 2004 | clearance is an issue. Again the best way to see if each printer will work is take "worst case scenario" and see which machine works best. - Automatic stencil cleaning. A must for high volume production. - Offline programming (optional) - An "enclosed print head" (Like MPM Rheometric/ or DEK Proflow CAN
Jul 28, 2004 | No-Clean Process very difficult to say that all no cleans must be cleaned for reliability. Cleaning in its own right causes many problems i.e leaving wax residues and activators from incorrectly cleaned no clean pastes, terrible to get off. Decent no clean liquid fluxes should completely volatise away so I always recommend if possible not to clean but if visible white powder(weak benign organic acid) is left then process the boards through a reflow oven at glue profile temps and this should volatise all organics off and not interfere with the rosins from the paste. Worth a try and it does work well.
Jun 12, 2004 | - Not much. Stencil aperture reduction is done - generally upto10%. Aperture shape is also changed for some boards, as recommended by IPC to reduce solder balls formation due to paste printing related matters. Stencil cleaning is done automatically by the m/c and is programmed to do cleaning from bottom
Apr 29, 2004 | corners of the board. With the vision you don't really have to have a Mylar frame to align the board for the first time, it just makes it easier. Without a Mylar frame you do the bomb sighting through the stencil to the board like I described previously. In this process you would clean off the solderpaste
Apr 1, 2004 | Thanks for the input. I dont have a component specific stencil thus, cannot paste the lead pads. I would apply no clean flux to the pads on the PCB and dispense a dab of paste on the ground pad of the PCB. >>When these boards are built new do we not have solder >>paste on the ground pad
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