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 Sep 13, 2002 |
... Via in pad - partial encroachment - via partially in pad Please provide different graphical views of possible via in pad solutions if you are aware of with design rules. - complete Via in pad - partial encroachment - via partially in pad What are the pad sizes we should avoid via in pad for? - complete Via in pad - partial encroachment - via partially in pad Is it okay to lose soldermask dam using via in pad? Does this lead to cold solder joints? - complete Via in pad - partial encroachment ...
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Nov 3, 2006 |
via tenting and pluging Via filling methods are: * Tenting * Plugging * Capping * Flooding Tented Via. A via covered with dry film soldermask; the via is not filled. When tenting from both sides there may be issues with trapped air that expands during mass soldering. Plugged Via. An additional operation which is done independent of soldermask application. The via is filled with a non-conductive material. Capped Via. An additional operation which is done independent of soldermask application on ...
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Feb 22, 2008 |
Tented Via's Steve, Trying to keep wave solder from coming up the via' from the bottom and adhering to the via's and via's pads during wave. We use WS flux thru-out the whole process. I have been concerned about possible flux intrapment in the via's. That's a good point. We really don't want/need to "Plug" the via's. My understanding of "Tented" via's is just a layer of solder mask over the via's not allowing solder to adhere. Sometimes it plugs the via and sometimes it does not, but it ALWAYS ...
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Sep 25, 2001 |
... T DO VIA IN PAD!!!! [We�ve talked about how much we like via in pad previously in the fine SMTnet Archives. ;-(] Many of the design tricks for accommodating VIP don�t work with BGA pads. ;-( * Increase the BGA pad size with a small bubble on one side of the pad you�re using now, put the via in the increased area of the bubble, and specify solder mask over the increased area. Duhh!!! * Specify a plugged and plated-over via. * Specify solder mask cover over the bottom side of the via. [This ...
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Sep 17, 2002 |
via in Pad Hi all Experts, Desperately need your help on the following questions on Via in Pad and want to understand each of them wrt : - complete Via in pad - partial encroachment - via partially in pad 1) What is the general feel for via in pad for upcoming designs? 2) What are the manufacturing bare PCB's related concerns, issues and possible drawbacks for using via in pad? 3)What are the assembling PCB's related concerns, issues and possible drawbacks for using via in pad? 4) Will solder ...
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Sep 14, 2002 |
via in pad I have the following questions on Via in Pad and want to understand each of them wrt : - complete Via in pad - partial encroachment - via partially in pad 1) What is the general feel for via in pad for upcoming designs? 2) What are the manufacturing bare PCB's related concerns, issues and possible drawbacks for using via in pad? 3)What are the assembling PCB's related concerns, issues and possible drawbacks for using via in pad? 4) Will solder flow thru. the vias and cause solder ...
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Mar 4, 2002 |
Filling via holes during the reflow process First responding to your questions: * Is it possible to add the via holes to the stencil and print paste into them and expect them to plug? => Yes, providing the surface of the via is solderable. * If so, how much paste? => Vias come in various sizes. Boards vary in thickness. So, the amount of paste to fill a via varies. Roughly, you�ll need twice as much paste as the volume of the via that you want fill. [So generally, overprinting the via pad is a ...
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Jan 11, 2010 |
via capping SR1000 is commonly used for tenting. Search the fine SMTnet Archives on : tenting Someone gave us this note. We have lost their name. It seems to be good advice. If Liquid Photo Image (LPI) solder mask is required, do not tent via holes. Tenting the via holes with LPI solder mask will result in the following problems: * Incomplete encapsulation of the via hole * Exposed copper/metal on via holes * Solder on via pads and in holes * Uncured solder mask in the holes, which result in ...
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Apr 12, 2004 |
Large Voids with Via in Pad Large voids are common in via in pad [seach the fine SMTnet Archives for earlier laments], especially in blind via. Observations on your via out gassing theory: * If the copper plating on your via is GT 1 thou, there will be no outgassing from the glass laminate through the copper. * If the copper plating on your via is LT 1 thou, there could be outgassing from the glass laminate through the copper. * If the copper plating on your via is cracked, there will be ...
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Apr 11, 2002 |
Tenting via(s) under BGA & CSP? We are using 1mm pitch BGAs with a great quantity of via(s) under the component. Very shortly we will be placing CSPs with .65mm pitch. Our via(s) are solder masked, however we generally have a percentage of them that the masking is thin enough that the via(s) are open, or has a substantial indentation in the via aperture. My concerns are, if a PCB is mis printed and needs to be cleaned that not all of the paste can be washed from the via opening or depression in ...
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Feb 19, 2002 |
BGA Via Plugging Guideline for Tenting Interstitial BGA Vias It is difficult to give a complete recommendation on via tenting without an idea what process conditions are required (ex: wave pass, double reflow, rework etc.). Via Pads (as Test Points) - On Bottom The need to use the bottom side vias pads as test points is acceptable in all cases except wave. If using PTHs and not blind / buried vias, the via is connected from top to bottom and so the bottom side of the BGA via can be used for test ...
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Jun 11, 2004 |
Via in pad We currently have an issue with via's in pads which we have been living with for some time. The problem has now escalated with the need to increase the via hole size to achieve PCB fabricators aspect ratio's. We are now not only experiencing solder drain from the joint but due to the increased via size we are also finding that the solder runs straight through the via forming solder balls on the underside of the land. Via plugging is being investigated but is unlikely to be qualified ...
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Jul 15, 2008 |
... PCB from Supported Via Holes Hi Armynski, I sell for an offshore board house, yes, it is common for offshore board shops to fill vias. The bubble is caused by air entrampment within the hole it self, when heat is applied during Hot air and the via is covered on both sides the entraped air can expand and blow out making the solder mask blister on one side of the board. Solder mask in via holes is done for two reasons: 1) Board Designer left no solder mask reliefs for the Via's in their design ...
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Mar 15, 2000 |
... caused by the via preventing good stencil gasketing. * Poor component reflow, caused by the via holding the component out of the paste. * Shorting between the component and the via, caused by solder flowing up from the wave through the via. * Shorting between the component and the via, caused by solder flowing up from plating within the via. * Shorting between the component and the via, caused by the component metalization touching the via. * Shorting between the via and traces, caused by solder ...
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Nov 23, 2007 |
via under a smd pad ? There a several things you can do to prevent the solder wicking down the hole with the current design, and that's where you should focus. Cost goes up as you go down the list, but in neither case do you need to respin the board, have solder starvation, nor need to do more than little to no rework. * Via plug - From opposite of component side, 50~75% of via, nonconductive epoxy. * Via fill - From opposite of component side, +2 mils, -10 mils of conductor surface ...
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Mar 7, 2006 |
Via holes and Wave Solder Our ICT Guy here at my company loves to use lots of via holes as test points - via holes which are 0.040" diameter, and spaced at 0.004" edge to edge spacing! He doesn't like to tent the via's either, so I always battle via-to-via shorts at the wave on an almost daily basis. Any knowledgable ICT Engineers out there who know of a probe style that can pierce through tented via's? I am trying to get my company to make a PCB Fab change requirement that all via's used as ...
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Feb 26, 2001 |
via as test point First, I don�t understand why your board fabricator can�t do a good job plugging your vias. Additionally, when you consider that they forgot to plug the first batch of boards, it makes me wonder if they are desirable as a supplier. Generally, we use "via in pad" (VIP) to allow test assess on the bottom side, as you discuss. VIP requires a controlled process by the fabricator. Specify no plugging [or tenting] and a via "open-ness" requirement and it�s consistency to the ...
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Feb 26, 2001 |
via as test point I'm working a problem and looking for your input. Here the deal: Two sided mix technology board. Test is using unmasked via points on bottom for test points. Our fab drawing states tent via points on top side. First set of board came in with no tenting making the vacuum fixture at test nonfunctional. Second set of board came in with "plug via" and for some reason this was not good for test either. Test want the stencil modified to put past on each via to accommodate connection ...
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Apr 27, 2007 |
ICT Question, Via holes and Probes For those of you who use via holes as test points, and the via holes must be filled at the wave, is it necessary to have a "dome" on every single test point, or is it sufficient to have the via "filled" with solder? The ICT preson here insists that there be a "domed" fillet, and for those of you well versed in soldering mechanics, we all know that's hard to achieve all the time on 20,000+ via's, especially since it is just a hole, with no lead that helps ...
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Jul 8, 2002 |
... study by Roger Wild at IBM that showed an unfilled via to be the most reliable, a completely filled via was almost as reliable as an unfilled via, and a partially filled via was not at all reliable. See the more we talk, you end-up being better off by not even filling the via at all ...
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Feb 20, 2008 |
Tented Via's Yea, I'm still here.....sigh. Got bridging problems. These assemblies are SMT topside, then go thru wave for thru-hole components on topside. These assemblies have many, many, many vias VERY close together. We have a problem with solder from the wave pushing up thru via's to the topside, if the vias are under an I.C on the topside, then we have had, and the potential for, a solder bridge between via's under the I.C. Can't SEE the bridge with the naked eye, if you know what I mean ...
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Mar 7, 2005 |
Via-in-pad Via in pad can have any size hole, but you're correct. The larger the hole, the more solder that is scavenged from the solder connection. We believe that a proper via in pad design will either: * Move the via to the edge of the pad and cover the via with solder mask ... OR * Plug the via in the pad and plate over the plug. That's it. That's the list ...
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May 2, 2003 |
... blind uvia's in pads Via in pad is the most efficient use of space. Blind via seems to be blamed for this. Cross-sections (send me some) will probably show a void still existing in the via or spherical voids aligned near the component pad side. One can estimate the volume of volatiles (assuming bone dry air) creating at soldering temperature. A 5 mil diameter cylinder (simple approximation of a blind) will produce a 5 mil diameter void sphere, yet I bet the void in the via and voids near the ...
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Feb 7, 2002 |
BGA Via Plugging When double sided BGA's are used on an .062 FR4 10 layer board should via's be plugged and tented? The CACHE chips being used are PBGA's 1.27mm pitch. The pad size is .030 and the finished via dia. is .010. This is a dogbone type pad and via design. My concern is the CACHE chips are directly over one another on top and bottom. The current design has the via's tented on the secondary side of the board. No plugs are used. What is the best way for this type of design? Plug and tent ...
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Apr 13, 2004 |
Large Voids with Via in Pad These voids only appear in the solder connections that have a (via in pad). The pads that do not have (via in pad) do not have any voids. Profile is 60 seconds above 183 C and peak of 218 C. The BGA is an OMAP lead free,I am using standard eutectic solder paste and the profile matches perfect with the vendors recommendations. Since the voids only happen on pads with (via in pad) I still feel the boards are the problem. When I run this same OMAP lead free BGA on other ...
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Jul 8, 2002 |
solder pop out from via hole at secondary reflow Hi Guys, We prints solder paste on via hole as the holes are used as the test points. This is a clean process. In normal production, upon completion of a primary side, board will proceed to secondary process immediately. The problem happened when brds which were completed primary side and brd sent to wash as we have a 3 days vacation. After the vacation, brd were then proceeded for secondary process ( without baking ). Via hole were also printed ...
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Jun 3, 1999 |
Wave Solder Problems - VIA HOLES I'm encountering a new problem at my new company that I haven't encountered before in my past life - and that's Wave Soldering VIA holes. We've been getting a rash of defects that we call in this company, "insufficient solder in VIA hole." These defects result in failures at ICT. Some of our PCB's have over a thousand (.013" dia.?) holes, and yes, they're plated-through. I've checked for everything required to make a solder joint - flux, heat, and sufficient ...
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Nov 21, 2007 |
via under a smd pad ? From info I have been told from design standpoint, via in pads helps with managing EMC issues with working design, in particular for high speed digital/dense populated type PCB's. We had a manufacturing customer that had very low yield because of this via in pads was two big and solder was drained away from the pads - 1000s of pads on design - lots of rework. It can be done but via size has to be as small as possible, or preferably plugged vias used with solder. This all ...
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Nov 20, 2007 |
via under a smd pad ? In my past experience, having via's under or attached to SMD lands produces risk. Solder will not consistently wick the same if it is being drawn into a via. This has also caused issues from solder wetting through the via to the other side causing a small bump. Which in turn, causes unseated surface mount components on 2nd side placement. I would not want to add any risk by putting via's under SMD's or in SMD lands...especially with the smaller components being used ...
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Nov 3, 2006 |
via tenting and pluging HI ALL, can anybody clear me what is via tenting and via pluging?? second one, if i use via in pad for an.5mm bga what care i should taken, what should be the soldermask open in top and innerlayers for via?how it will directly connect to top layer pad??? clear me ppl THANKS shivam
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Mar 22, 2005 |
Via tenting/filling with BGAs Q1. What are you guys doing for filled/tented/plugged vias on the BGA site? A2. 2221A, 4.5.1 tells you the vias have to be tented on both sides. Q2. What type of issues can this cause if using no filled/tented/plugged vias on the BGA site? A2. BGA via with no tenting, plugging, or filling allows: * Via to scavange solder from the BGA solderball connection. * Heat from wave solder pot to reflow BGA solderballs. * Solder from wave solder to wick to the BGA solderballs ...
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Dec 17, 2004 |
BGA Via Tenting I got this issue: Voids in almost every ball of my BGA's processed since we changed our BGA via tenting to double tenting. The tenting is done with a dry film application to fill the via from the solder side then apply LPI Mask on the surface of the (solder side) PWB. Then same process on the component side. Dry film first to fill then vias the LPI. Will that be a possible source of my BGA voids. We do not have this problem prior to switching to this Via tenting process. Thanks ...
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Dec 17, 2004 |
BGA Via Tenting I goy this issue: Voids in almost every ball of my BGA's prcessed since we changed our BGA via tenting to double tenting. The tenting is done with a dry film application to fill the via from the solder side then apply LPI Mask on the surface of the (solder side) PWB. Then same process on the component side. Dry film first to fill the vias the LPI. Will that be a possible source of my BGA voids. We do not have this problem prior to switching to this Via tenting process. Thanks for ...
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Jul 30, 2004 |
what's the difference between a thru vias and a blind via? Consider a 6 layer board. The Through via gets drilled from top layer to bottom layer. All 6 layers has the hole drilled in it. A blind via is a via that does not got through the entire 6 layers. It would go from layer 1 to layer 2. or layer 6 to layer 5. There is also a buried via, they are vias drilled on inner layers creating inner layer pairs. Hope it helps
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Feb 26, 2003 |
removing solder from a 0.015 Try this: * Lay the board onto a solder pot with the via in question on the heat. * Push the wire into the via. * Step back and pat yourself on the back. Since you probably have components in the area of the via that you don't want to cook, try a variant of the above by using a soldering iron in-place of the pot. Finally, bag cleaning the solder from the via and just solder the wire to the via pad and drop a dollop of indutrial strength epoxy to secure the wire ...
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Feb 11, 2003 |
Plated through via's in pads. Use a PCB fab house that is capable of "Conductive Via Filling" is the way to do it right. A conductive epoxy is used to fill the drilled via PRIOR to final plating. After final plating, the surface of the "Filled Via" will appear to be the same as the other BGA pads. This will not require a manufacturing process change to use different stencil thickness. ... More Paste, ... More Waste ...
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Feb 27, 2002 |
0402 via in pad Hi, I need help to understand further on the via in pad for 0402 requirement. If I were to do the DFM over the brd design which consist of 0402 with via on pad, what is the criteria that I should look for ? I learned that the via in pad does not work well on ENTEK finished, and the pad design need to be a little bit bigger. IS it right ? Our current pad side is 21X 21, with the gap of 16 mil. What would be the best pad size for 0402 via in pad ? thx ...
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Sep 25, 2001 |
Solder flow thru via on pad Been there - done that. Makes a mess on that 2nd reflow process- doesn't it!?!?!? This is caused by design. If the open via is located in the land area, it will flow thru the via and cause pumps on the opposite side. You can have your vias filled with mask and save yourself some time bumping heads with your design guys. Unless your ICT guy is using this via for test, then you'll have to have a strip of masking placed between your solder paste and the via - if possible ...
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Jun 4, 1998 |
... always have a strip of copper before connecting to the via which tends to lessen heat sinking thru the via. | | B. Should you feel that option A is not the solution for you then may I suggest that on the wave side of your board that you button print (tent) all your via holes (this is a 5 mil oversized "via only" gerber file that your board mfgr can use for the first pass solder mask ) and then remove all your via apertures on your solder mask gerber file such that you end up with a ...
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Jul 7, 2008 |
Datasheet for VIA BGA *VIA VN896CE; *VIA VT8237A; Thanks ...
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Aug 24, 2005 |
Brd(Electroylic Gold finishing) got blisters The blistering is around the plugging via. I can forward you the pic. For the plugging process, I'm not too sure how they plug. What is the correct practise for the plugging via. Now, what they did is. They will do a tenting process for both side. Then open a solder resist of 0.4mm dia on the masked via (dia 0.2mm).Via @ BGA area, they will do 0.3mm solder resist ...
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Jun 11, 2004 |
Via in pad We figured you were going to say that. Pay me now, or pay me later, you call it. As an alternative: * Cover the backside of the via with masking tape that will take soldering temperature, like Kapon, or a temporary solder mask * Enlarge the aperture of the viaed pad to compensate for filling the via with solder * Print paste on the topside of the via, reflow, etc as you normally do * Remove tape, TSM, whatever
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May 12, 1998 |
Paste Penetration in Via for Paste Through Hole Help! We have been doing some trials on Paste Through Hole and have encountered a problem. The screen is designed (as is suggested in technical info re PTH) to give double the paste volume required to fill the void between the pin and via. The problem we are encountering is that a) we are finding it very difficult to get the calculated volume into the via, and b) approximately 1/5th of the volume is then displaced onto the pin end after insertion ...
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Aug 23, 2005 |
... And when we had this finishing with plug via, the blister issue pop out. My supplier claim that this is due to the plug via. Which I don't know how true is that. My brd is a 4L brd with 1.6mm thickness. So far, this blister also pop out @ the brd with 1.0mm thickness, 4L brd. The vendor is suggesting to do a solder resist of 0.4mm on the via (hole dia 0.2mm), open on both side. Instead of plug via, they do half plug via. As for the via @ BGA, they will control the solder resist at 0.3mm. We ...
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Jun 4, 1998 |
... otherhand always have a strip of copper before connecting to the via which tends to lessen heat sinking thru the via. | B. Should you feel that option A is not the solution for you then may I suggest that on the wave side of your board that you button print (tent) all your via holes (this is a 5 mil oversized "via only" gerber file that your board mfgr can use for the first pass solder mask ) and then remove all your via apertures on your solder mask gerber file such that you end up ...
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Feb 16, 2000 |
... the via. 4 Use a two step solder mask process to tent vias. First, put a layer of dry film down and print it with via image. Then coat the board with liquid solder mask. Then print that image. This produces a part with tented via's and liquid photoimageable to ensure that there is no entrapment in the via holes. The issues there are the additional standoff, especially those close to the BGA pads and LT 0.025" SMT ... that definitely affects the solder print resolution/process ... and it it�s ...
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Feb 16, 2000 |
... the via. 4 Use a two step solder mask process to tent vias. First, put a layer of dry film down and print it with via image. Then coat the board with liquid solder mask. Then print that image. This produces a part with tented via's and liquid photoimageable to ensure that there is no entrapment in the via holes. The issues there are the additional standoff, especially those close to the BGA pads and LT 0.025" SMT ... that definitely affects the solder print resolution/process ... and it it�s ...
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Dec 15, 2005 |
BGA short You might wanna try a small reduction in your stencil aperture. For example, for a 30-mil pad go 26-mil square aperture with 8 to 10-mil radius on your corners. Also, look at your designs. Is there enough resist between your pad and ball? Another thing that's bitten me in the arse.... excessive HASL on the VIA's which caused top-side gasketing problems at the Top-Side printer. The HASL "icicled" out of the via's due to excessive HASL, and plus the VIA's weren't tented ...
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Jan 31, 2005 |
Is test vias a good idea?? Yes, probing via is perfectly acceptable. Via: * Pad diameter is 0.028 inch * Via pitch minimum is 0.50 inch ... all of which is fairly common, even when probing test pads. [Your English is fine, at least as good a half the English speakers here ...
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Jan 21, 2005 |
BGA Via Tenting I work for a board house and our proceedure for this process is the following, We cover the via pads leaving the hole open and then apply the surface finish and then go back and Cover the Via with a second operation. By doing this you do not entrap chemicals in the hole causing contamination or leaching or blown holes while it is going through a baking or hot air process ...
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