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Dec 22, 2014 | My customer made a process change to overcome a design flaw. The PCB assembly mounts in a plastic housing. The PCB mounts to the front housing via plastic stand-offs. They had to change a connector on the back side of the assembly due to long term availability. This cause a small clearance issue with the rear housing. To fix this, they have instructed us to trim one of the 4 stand-offs shorter by .160" to pull that corner down to clear the rear housing. So 3 corners of the PCB are the same height, and one corner is 0.160 lower, intentionally bowing the PCB. We can't shorten all 4 due
May 13, 2014 | low thermal emf solder & paste - SAC 405 Hello davef - could it be you are confusing low thermal emf (Seebeck coefficient) with low temperature solder ? I am looking after solder wire and paste with low Seebeck coefficient - cadmium based alloy was OK but banned in europe due to RoHs directive - so looking for substitute. classic Sn Pb is around 1.5µV/K - low thermal emf is around 160nV/K - everything < 0.3µV/K can be considered. material should be RoHs compliant Thank You - Michel
Nov 25, 2011 | Low temp Lead Solder Paste Dear All, I´m looking for a low temp solder paste with Lead. I know that, with lead free, is common solder paste with bismuth for low temp in Pin in Paste line, but one customer aks me about low temp solder paste with lead. If anybody knows about and can help. Thanks in advance for all.
Nov 11, 2011 | Thanks guys, But for the cleaning process we already have a chemical product to clean flux residues and other contaminant. But it seems that we can't rinse properly under low stand-off components and we find trace of our chemical under some ceramic capacitor. We don't want to clean with alcohol
Oct 31, 2011 | We're not sure what a 'sticky roller' is, but will it: * Remove ionic materials * Leave no residue * Clean the walls of through holes and vias * Clean under low stand-off BGA and LGA
Aug 5, 2011 | * Attaching thermocouple to CSP or BGA is a challenging task. Usually a hole is drilled at the center and the thermocouple is routed through the bottom of the board and to the area of interest. In particular, since the CSP stand off is very small, a tunnel is milled next to the drilled hole
Jun 15, 2011 | plan to use single port nozzles with dual stand off on all 4 spindles. These nozzles are very costly if purchased from Universal and the lead time is 3-4 weeks. I would appreciate if anybody knows about a company that manufacture's these type of dispensing nozzles for PDP head and are cheaper
Jan 28, 2011 | process, expensive fluid, some parts cannot be processed due to fluid drag-out, longer cycle time due to batch, need stand-off tooling for double sided boards. Email me if you want more specifics Shannon, We have been using VP for all of our lead free production since 2007. Here are the items I can think of off the top of my head. Pro's - small footprint, minimal profiling needed once machine is understood, oxygen free soldering process, stable peak temp, low energy usage Con's - batch
Jul 14, 2010 | residue fluxes. If you find yourself in that situation, you will have some interesting choices to make. * The one time that it makes fairly inarguable sense to use low res flux is on boards with low stand-off components. Probably, you need to make the same presentation to your customer that you made to your boss when you proposed changing to low-residue fluxes. Hey boss [customer], here's what's GREAT about low-residue flux. Here's how we can: * Lower our unit cost * Improve our product Look at this link for some papers that may help: http://www.smtinfo.net/Db/_No-Clean%20Technology.html Additional points are: * Some low res fluxes are cleanable * Recognize that some products just don't do well with low
Jun 18, 2010 | joints of components to add stress on the PCB, 2) Difference in the coefficients of thermal expansion of the PCB laminate and the stiffner/stand-off placed above the board. Have any of you guys faced such an issue? I would appreciate it if you could explain the phenomenon or how you managed to address
Jun 18, 2010 | for radial. What I ended up doing is placing glue dots early in the process at SMT. The dots were just enough to let it exaust from the top of the board and my solder problems were resolved. Most radial machine placed parts are made with a slight flat stand off which keeps the material off the board, so I
Aug 13, 2009 | increases the stand-off of a first-side BGA slightly as the solder goes liquid during the second reflow cycle. Increased stand-off is a good thing, it helps make the solder joint more compliant. * Keep the heavy-weight BGA on the second side to be reflowed. * If the above fails; print paste, dispense glue
Mar 24, 2009 | at different stand-off heights and squirt some colored flux beneath the slugs. Send it through a reflow oven to bake it some, and then it's bathtime! Then just take a gander at what the plate looks like after it comes out of your cleaner. That'll show you without a doubt, what your cleaner is capable of. [S It is very common to use low residue flux with low-standoff parts.
On the other hand, sure you can clean under low-standoff parts. We've talked about this previously. Search the fine SMTnet Archives to find threads like:
Dec 17, 2008 | Ok, thanks for the info, fortunatelly we already have our Camalot glue dispenser machine In-line with our MPM, for helping whit the high stand-off components.
Dec 17, 2008 | Ok, thanks for the info, fortunatelly we already have our Camalot glue dispenser machine In-line with our MPM, for helping whit the high stand-off components.
Dec 11, 2008 | to expand your line by adding another piece of equipment to dispense glue. However this method would require a more difficult setup for components with a higher stand off. If no through hole components are ed and wave soldered further on in the process, then obviously doubled side reflow is preferred.
Nov 14, 2008 | Yes, courtyard gives you the space requirement of a component. Sometimes, the working space of a rew
Nov 14, 2008 | > For your pad layout and spacing between > components, look here: _a class=roll > href
Nov 13, 2008 | For your pad layout and spacing between components, look here:
Nov 12, 2008 | SMT Design: Package distance and stand-off height Hi all,
Assuming that i were to design a PCB and there are multiple components, what is the minimum spacing required to ensure that i won't have problems in my SMT process later on?
Also, is there a minimum component stand-off height spec as well? Can we control the component stand-off height
Nov 12, 2008 | SMT Design: Package distance and stand-off height Hi all, Assuming that i were to design a PCB and there are multiple components, what is the minimum spacing required to ensure that i won't have problems in my SMT process later on? Also, is there a minimum component stand-off height spec as well? Can we control the component stand-off height
Apr 15, 2008 | High mix low volume Hello I would like to ask you what kind of production do u treat for high mix and low volume. I mean what is your definition for this high mix and low volume - is 5 changovers for shift is high mix and low volume technology? And what kind of SMT platform configuration u are using for high mix and low volume? regards peter
Jan 23, 2008 | ball deformity, will there is an issue to short circuit ? One on my suppiler say it is not an issue as the solder will be reflow later, isit correct? For my BGA incoming visual inspection of BGA components, i included inspection of 1)Ball diameter 2)Ball coplanarity 3)Ball Pitch 4)Package stand-off
Dec 4, 2007 | of masking & fixture, we using glued to make the component stand off the wave which will be done a good job to make fillet at the component terminal. You lost me here. Are you using peelable mask instead of a fixture? If you really want to reflow some parts and wave others, get a new paste stencil without
Dec 3, 2007 | with a fixture for wave and THAT's why you need good reflowed joints, why would you put glue on them? A: Some of the component is near to the THP and that'why i've got to glued the component. Btw, to save time of masking & fixture, we using glued to make the component stand off the wave
Sep 13, 2007 | 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 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
Aug 20, 2007 | Manufacturing already tried to get a design change but no chance. I guess because the designer is afraid the components could get bent too much if they are mounted with a stand off. Of course everyone who has to manufacture this fist sais: why don't you use standard design rules with 2.5mm lead
Apr 23, 2007 | , that are the same size as the largest BGA you think you'll do. Glue them to the glass plate at different stand-off heights and squirt some colored flux beneath the slugs. Send it through a reflow oven to bake it some, and then it's bathtime! Then just take a gander at what the plate looks like after it comes out
Dec 6, 2006 | Successful solder paste overprint is a function of the solder paste rheology, solder mask and through hole component stand off. * Solder mask with a high surface energy will permit a larger overprint than a solder mask with a lower surface energy. In large overprint a solder bead can be formed with a low surface energy solder mask. * In addition, more solderable land finish (e.g. HASL versus OSP), lead finish and a solder paste with higher wetting strength, all assist in making the overprint reflow process more robust. * Solder paste print should cover the entire land, in order to maximize
Nov 6, 2006 | existing process for LCC's using Triklone N) or different flux chemistry so that it doesn't matter if they're clean. It's something to do with the surface tension of water and the stand off height of the component.... If money is an issue there are alot of these machines out there on the 2nd hand market What low profile components are you dealing with? We have had problems with cleaning under leadless chip carriers using an aquastorm 200 with Kyzen Aquanox 4520T and the general concensus is that you will not clean under this type of device with an aqueous wash. This left us with solvent (our
Oct 17, 2006 | 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 11, 2006 | to the PCB with a stand-off of about .050" up off the board. You can then clean beneath it with the added benefit of improved reliability from TCE mis-matches. -Steve Gregory-
Jul 8, 2006 | Low volume prototyping Hi, I would go MYDATA rather than an "entry level" machine. The MYDATA low cost second hand units run the same software as their top of the line units, as well as taking the same feeders, so if you want to go faster and upgrade to a faster model, you can use the same feeders. There are lots of MYDATA units around low cost, and they can be upgraded to the latest software if required, and run loads of second hand feeders available, because all MYDATA's run them. Your also fully automatic, and can even conveyer the machine if you buy one without conveyers, and you get vision. It's a much
Jun 14, 2006 | Low Flux Residue Solder Paste I'm looking for a No Clean low or an ultra low flux residue solderpaste (SAC305 and Sn/Pb). Any Recommendation? Is there something in the datasheet that will tell if a solder paste is really a low residues flux. Also is there a method to clean the fluxes off a low profile LGAs? Thanks in advance
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
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
May 23, 2005 | And Gate If one/both inputs are low, output will be low If both inputs are high, output will be high
May 22, 2005 | If 1 & 2 are low, then 3 will be low: *Always *Sometime *Never
Mar 16, 2005 | What is the joint stand-off gap anticipated after the board level assembly and reflow? If it is designed per CSP standards, there should be no issue in water cleaning. If the gap is 90 � 100 micron, better to go with a no clean paste. His needs good process controls.
Mar 1, 2005 | We are using a GDM with a linear piston pump fitted to dispence adhesive on 0603's. Use Universal part number 43273801 needle with a 42346504 piston. The single needle dimentions are 0.010 ID, 0.028 OD, 0.005 stand off
Nov 1, 2004 | There is no IPC requirement for reworking BGA with either paste or just flux. While we generally use flux only, general consensus is that both methods work equally well. Adding solder paste, while more difficult, should result in larger package stand-off which will improve reliability.
Aug 3, 2004 | in the washer performance. [Assuming of course that the BGA has enough stand-off to allow wayer to penetrate under the BGA. If the BGA ball diameter is 0.030" or larger, most modern in-line aqueous cleaners do a fine job.] Otherwise, it is an issue of surface tension, pressure and flow rate. With straight water alone, surface tension of water makes it difficult to get under low standoff parts. If, however, you add a suitable surfactant agent, so that your cleaning solvent gets under the parts, then it becomes an issue of how much fluid delivered, how fast. There are cleaning agents that will work for low standoff devices, without destroying the materials of construction. We've talked about surfactants perviously on SMTnet. It's not surprising that your BGA ball is not perfectly round. We expect a kind of flattened bulbous disk [what the word inventors describe as "the collapse"]. Ion exchange
Jun 1, 2004 | We agree with John. It's possible to clean under 1.27 and 1 mm BGA. These devices have a reasonable stand-off that allows cleaning of water soluable flux residues with modern cleaners. So, if you have process problems with low-res fluxes, what makes you think you will not have the same issues
May 7, 2004 | Either method is acceptable: * No IPC approved method * Applying flux only is easier than applying paste * Paste gives a higher stand-off, which should improve reliability
Apr 13, 2004 | , not necessarily because it�s Class III or aerospace. There�s probably a NASA [er, somebody like that] requirement for water washable flux. [See with low stand-off devices, like some QFP and some BGA, washing OA improperly potentially is far more damaging than using NC. Which; if you plan to use a garden house
Mar 25, 2004 | to the flux. If the flux is under a very low stand-off component, water may not be able to contact the flux. The cleaning agent (water) must have vigorous contact with the flux in order to remove it. In tightly spaced applications such as BGA�s, Flip-Chip, etc, a chemical additive is helpful to lower the wash solution�s surface tension, allowing adequate contact with the flux residues. Most wash systems place all of their effort on the wash cycle. After all, you are cleaning the boards primarily to remove flux residues. As a chemical additive is normally required for low stand-off components
Feb 20, 2004 | . As a down & dirty method for determining capability of cleaners: * Make some glass [heat resistant tempered glass] slugs that are bigger than the BGA you plan to clean. * Glue several BGA to glass slugs at different stand-off heights. * Squirt colored flux beneath the slug. * Send BGA/slug through a
Jan 22, 2004 | that it was made, you need to attach a high temp ball to the device using eutectic solder. During manufacture only the eutectic solder is supposed to reflow, leaving the high temp ball intact thus giving you the high stand off you need for thermal management. So reballing CGBA's is a nightmare. My advice, give
Jun 20, 2003 | Hi John- First, I do not have first hand experience so my input is pure theory. This type of package (in Some Cases) has a center grounding bonds and leadless legs ups the difficulty tremendously. With no stand-off from the Balls(or Legs) when the solder paste collapses during reflow the chances
Apr 1, 2003 | You're correct. There is no way you can aquous clean under a low stand-off part like a LGA. Your approach seems reasonable, given your constraints. [As long as your customer is paying, what the hey!!! Give 'em what they want.] Consider joining the 20th Century by changing to low residue fluxes
Jan 16, 2003 | for it and non for std tin/lead ot tin/lead/silver. Dave, like the idea's, similar to our train of thought, the problems with these are: 1. can't use hi melt as this crosses soem patent with IBM which would add to the cost.... we have get to component vendor to add copper stand off's for future buildss
Jan 13, 2003 | Hi folk's, I'm looking for some help full suggestions here... I've got a ceramic BGA with tn/lead / bismuth balls on it that is over collapsing due to the weight of the momponnet vs the ablity of theball to suppot them. We've spok eto the component vendor to get them to put copper stand off ? Alternatives to this process would also be welcome, we've thought of applying some glue dot's to act at stand off's but there are concern's if you ever have to repair these things and alo if you miss a glue dot (not that this would happen you understand) you could skew the device in one corner. all sensible