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Aug 22, 2019 | I have to agree with Dave here. Can you compare the datasheet pad recommendations to your design ? It may help to show the forum a picture of the bare PCB pad design along with a pic of the bottom terminations on the part. What Stencil thickness are you using here ? Component Skew during Reflow Process
Jul 20, 2019 | IPC-A-610F 8.3.13 Bottom Termination Components (BTC) ... Thermal plane void criteria shall be established between the manufacturer and user IPC-A-610F, 8.3.14 Components with Bottom Thermal Plane Terminations ... Thermal Plane Void Criteria - Acceptance criteria will need to be established
Jul 19, 2019 | Double-check me on this, but I don't believe that A-610 [IPC-A-610] requires side fillets on QFN solder connections, because the sides of most terminations are not plated. Plating on the bottom of the termination is sufficient for a proper solder connection. A-610 seems to be more concerned with proper alignment and voiding levels in QFNs than solder fillets. Check the solderability of your components.
Jun 26, 2019 | Component drop after reflow Do you have any images that show the soldered terminations? Also images of the pcb terminations after the part has moved might be helpful.
Mar 28, 2019 | There is no industry standard for BTC stand-off height. "IPC-7093A Design and Assembly Process Implementation for Bottom Termination SMT (BTC) Components" just finished "Final Draft for Industry Review" in December 2018. It mentions stand-off height several times, but no definitive "standardy
Aug 24, 2018 | My first guess at the cause of your components skewing -- Termination pads on the board to not well match the the soldered terminals on the components, causing unbalanced wetting forces on the component terminations while the solder is molten.
Apr 28, 2018 | Hi, please go through IPC 7093, its only for design and assembly process implementation for bottom termination components. its says up to 50% voids will not reduce ant electrical and thermal performance.
Dec 2, 2017 | ) and improves assembly results by reducing voids. This technology will be available in the upcoming release of IPC-7093A - Design and Assembly Process Implementation for Bottom Termination Components.
Sep 20, 2017 | according to IPC-A-600. * Maintain operating procedures for setup and the proper operation of soldering equipment in accordance with J-STD-001. * Use Statistical Process Control (SPC) to control soldering processes in accordance with J-STD-001. * Inspect bottom terminated components to assure good
Aug 10, 2017 | How do you evaluate the soldering quality for those QFNs? X-Ray or AOI? For some QFNs (and other bottom termination components) it's not supposed to have solder fillets on toes. It's also noted in IPC-A-610 (Rev.F 8.3.13). Take a look at your QFN chip's toes under magnifying lens, you will see why.
Jul 4, 2017 | If you want in, 5-21h Bottom Termination Components (BTC) Task Group is in "Working Draft" revision from "A" to "B" of IPC-7093 - Design and Assembly Process Implementation for Bottom Termination SMT Components
Feb 21, 2017 | Solder splash from component terminal Thanks for input, dyoungquist. The condition here is without any flux or paste applied. Solder from component terminal started splashing by itself when put through re-flow.
Feb 12, 2017 | Solder splash from component terminal Hi fellow professionals, Wondering whether anyone has experience with solder splashing from component terminal. Have identified the source using the component without printing solder paste on PCB. Wondering the root-cause of the solder splashing from the component terminals. High temperature of the component solder itself.
Jul 19, 2016 | What kind of oscillator are you placing (Manufacturer part #)? I do not believe that oscillators fall under the "chip component" category. Even if they did, most all SMT oscillators that I have come into contact with have 1 sided terminations on the bottom side of the component. That being said , the criteria in section 8.3.2 (Rectangular or Square End Chip Components - 1,3 or 5 Side Terminations) do not apply. In the introduction for this section it is stated "For 1 sided termination, the solderable side is the vertical end face of the component". I would say that a upside down placement
May 9, 2016 | Your crystal should meet the requirements of IPC J-STD-002D Solderability Tests for Component Leads, Terminations, Lugs, Terminals
Jun 22, 2014 | I don't know. We never had craziness like this before lead-free. You should have the yellowish-metal analyzed to be sure. Guessing: You're seeing this color on the terminations of components, not on the bulk of the SnX solder connection. If that's the case, here's what's going on, probably : * Bulk solder and component termination are blistering hot * High soldering temperature has melted the metal solderability protection on the component termination * Surface tension of the bulk solder has pulled the component termination solderability protection into the bulk solder, leaving behind the exposed stainless steel or nickel barrier * Thin nickel oxide films form on the component terminations that change color according to temperature or exposure time during soldering BR ... davef
Nov 20, 2012 | of luck. So to fully answer the question, and to have complete capability for prototype designs and components, you'll need a rework station with both top and bottomside heating, split vision optics for alignemnt and placement of fine pitch or bottom terminated devices, something similar to AirVac DRS25
Oct 25, 2012 | Here's a paper that may help http://www.ipcoutlook.org/pdf/assembly_challenges_bottom_terminated_ipc.pdf Temperature Impact * Profile didn’t have a significant impact on voiding difference in voiding between solder mask defined pad and no solder mask defined pad. Component Type vs. Voiding *Voids varied depending on the package type. [see Figure 11 below] Design Impact * More solder balls were seen on LGA packages. Solder balls were rarely seen QFN packages.
Jul 23, 2012 | If your pick and place can handle the part placements, you are most of the way there. X-Ray for Inspection of BGA and other bottom terminations = $60K(USD) and up. BGA Rework Station $40K and up. You can reball most any BGA with your Rework station. No panic with BGA, it is just another solderable component after you have done a few. 'hege
Mar 29, 2012 | In the IPC-A-610E standard QFNs are classified as BTC (bottom termination components). Most QFNs do not have a solder-able surface on the outside of the part. Usually the lead that you can see on the outside is copper and classified is not solder-able. On these type of parts no toe solder
Mar 4, 2011 | Bottom Termination Parts-Xray Inspection Criteria First, I would inspect for lack of solder bridges from the center slug to the outside leads. I would then look for evidence that the solder paste has reflowed beneath the component, without leaving too much void percentage. Typically we allow up to 25% voiding for these parts, in RF of the same solder volume. Shoot for about a 30-35% reduction of solder beneath the component. 'hege
Feb 17, 2011 | Having issues with soldering bottom termination components such as PQFN's. Want to begin x-ray inspection to verify wetting. Wondering about soldering acceptablility criteria? Bottom Termination Parts-Xray Inspection Criteria
Oct 5, 2010 | is typically much stronger than the termination. What type of components are these and how are the terminations constructed? A few years ago we had some 0603 varistors that had AgPd terminations. The termination metal went into solution in the solder joint and essentially left no mechanical connection Soldering Strength of 0603 Component Have you confirmed in an SEM that the break is in the solder and not in the termination? If not in the termination, is it in the intermetallic rather than the bulk solder? It's unusual for the break to be in the solder joint when chips are knocked off during handling. The solder joint
Sep 9, 2010 | You can reduce and almost eliminate voids and other paste related defects in LGA's BGA's, QFN's etc, by using solid solder deposit. Its been around for 24 years, 13 in the US. It is now included in the new IPC 7093 specification for bottom termination components (BTC's) Go to
Aug 1, 2009 | I have been working on Pb-free assemblies of screw terminals (terminal blocks). Unlike, other pin-in-paste conducive components, these component has square headed leads. We have been facing issues with the solder dripping into the oven. We were able to do the same assembly with Sn-Pb. Any Pin in Paste of screw terminals
May 12, 2009 | Hi All, I see more and more components like QFN or LGA with bottom-only terminations,with landpatterns getting finer all the time. I have no ppm-figures of our process, but based on a benchmark study by Agilent I'd say that 500 ppm is a decent value, especially for smaller series. Which means that if you assemble 100 boards each having 100 QFN-or BGA-terminations, 5 boards out of these 100 will be defective. With 1000 of such terminations half of the boards will not work! Repair is often more expensive than the value of the boards that wou want to save, in which case you could end up with piles
Aug 28, 2008 | Shelf life numbers don't mean dip. Are the parts solderable per ANSI/J-STD-002, Solderability Tests for Component Leads, Terminations, Lugs, Terminals, and Wires? If yes, go solder the parts. If no, get better parts from your supplier. Component Shelf Life
Aug 19, 2008 | Larry, It is generally bad practice to place high profile parts, like TANTalum Capacitors on the bottom side. They are more likely to shadow, and also, the odd termination that covers only a very small part of the body makes it prone to solder skips as well.
Jul 1, 2008 | I would like an interpretation of a solder fillet on a 5 side termination cap. (Ref: IPC-610, sec. 220.127.116.11). My question pertains to the definition of dimension F, and what constitutes the top of the fillet. Does the top of the fillet end at where the wetting stops on the component termination ? Or is dimension F measured from the top of the concave meniscus at the point where the wetting is on the same plane as the component termination? Fig. 8-27 seems to define the top of the wetting as dimension F. I have a dispute with a customer.
Jun 19, 2008 | Try: ANSI/J-STD-002, Solderability Tests for Component Leads, Terminations, Lugs, Terminals, and Wires
Apr 2, 2008 | Even though we can't comment on that specific part, you're correct. If the solderability protection on the terminations is not symetrical, it could result in tombstoning. We used to see this alot in smaller components, where the plating did not completely cover one of the terminations. Component Quality
Feb 18, 2008 | Hi everybody, I found a defect varistor 0603 Tombstone and poor welting when we use component that terminal is Silver palladium (Ag/ Pd) with Leaded solder paste (63/37). Then we change alternative component that terminal is Ni/ Sn the result not found defect. We would like to know 1. Silver palladium concern with leaded solder paste? 2. PCB has via on pad (defective location) when we use component that terminal is Ag/ Pd we found Tombstone. But after try to use alternative component that terminal is Ni/ Sn not found Tombstone defect. Why? 3. Do you have any suggestion for reduce or fix
Dec 3, 2007 | Epoxy on bottom of SMT component which will be done a good job to make fillet at the component terminal. 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
Dec 2, 2007 | Epoxy on bottom of SMT component The idea for solder at bottom side is for component such as SOIC, QFP and chip. This solder is needed since not entire bottom component had glue. that's why we're combining both solder paste and glue and reflow at the same time.
Nov 29, 2007 | Epoxy on bottom of SMT component stencil with home based aperture opening. Doyou have 6mil stencil? What is the opening? I'm not be able to solve the problem due to the gap between the pad and the terminal which causing non-wetting to my chip component. If the solder paste is not enough, you might be able to advice what Hi Dback, Yes, i'm open "dog bone" aperture for my chip component. this is to prevent solder ball issue. For fine pitch i'm opening square with full length and half width to prevent bridging. Btw, if "dog bone" is not for chip component, what is your opening for chip component? You using 5mil
Nov 28, 2007 | the component terminal if we mount the glue beneath the component. Plus, is there any issue if we using glue and masking 100% for bottom component before run through wvae sodlering? Q2:Do all components with the same standoff have the same / similar drop / missing rates? A2: not all but randomly. Q3: Are you Epoxy on bottom of SMT component Q1:What is the relation between component standoff and drop missing? A1:component standoff will identify either solder paste at SMT side can form the fillet at component terminal or not. Drop/missing component is totally out of the topics since i just need to know if there is any gap between
Nov 28, 2007 | Epoxy on bottom of SMT component is there any standard gap between the terminal and pad if we place the glue? SMT-4 mention as per what you understand which is using glue at SMT without solder paste and run at wave solder for the solder paste at the terminal. Glue supplier recommended to cure at 150C but if combine with solder
Nov 27, 2007 | Epoxy on bottom of SMT component Dback, Current method is by using dispenser machine to dispense the glue at PCB. This non-wetting is randomly and not repeating to the same location. My adhesive height is 0.01" to 0.035". Is this will cause the component to had a gap between the terminal and pad? Yes, i agree with you that the glue will be cured first and hold the component. Btw, is this any related with stencil opening since my current opening for chip component is dog bone whith thickness 6mils and i believe this cause the non-wetting issue. The adhesive height being control by using the measurement tools which called
Nov 27, 2007 | , the adhesive height should be that of the distance between the bottom of the component and the surface of the PCB. The adhesive cures faster than the solder paste, so once the adhesive sets, the component terminal may be "floating" above the solder, causing the terminal not to wet. Can you control your Epoxy on bottom of SMT component Shy, What is your current method of applying adhesive? If the terminals of the component that has adhesive are not wetting ( or not forming a solder joint I think we are talking about ) after reflow, then you must be applying too much adhesive. As a rule of thumb, if I am not mistaken
Nov 27, 2007 | Epoxy on bottom of SMT component How many mils the gap between the terminal and pad? Your practice is for technology SMT-4? What is problem with glue cure? is it due to the reflow profile? how long the glue can be keep in room temperature with humidity 40-60?
Nov 27, 2007 | Epoxy on bottom of SMT component C1: is there any gap between the pad and terminal if we place the glue? R1: Yes, there is a gap, but it is easily bridged by the amount of solder in the wave. C2: Btw, my practice to print solder pate then punch glue then PNP component and finally reflow. R2; Our practice is to print glue, place , cure, then wave solder C3: Also we find drop/missing chip after wave eventhough we glue the component. R3: There are times when components are not in-place after wave soldering. Odds are: * If the component was in-place prior to wave soldering, there is a problem with glue cure or age of the glue
Nov 27, 2007 | Epoxy on bottom of SMT component is there any gap between the pad and terminal if we place the glue? Btw, my practice to print solder pate then punch glue then PNP component and finally reflow. Also we find drop/missing chip after wave eventhough we glue the component.
Nov 26, 2007 | Epoxy on bottom of SMT component currently i'm open my stencil aperture is 80% from the land pattern. is this will cause insufficient solder at the terminal component or not? the stencil thichness is 6mil and the board run using SMT pallet which i consider there will be no option for warpage. since you're rarely see this problem, you might help to give idea how to eliminated this kind of issue which causing my SMT component to be non-wetting after reflow.
Nov 26, 2007 | Epoxy on bottom of SMT component Yes, i'm agree with you davef but i'm not put the chipbonders onto pads. i'm put the chipbonders at the beneath component (center between both component terminals) which the idea is to hold the component during wave soldering which might cause the component to de drop/missing. Is this chipbonders will cause any effect at the component terminal since it will cause the component slightly higher than the pad and solder paste?
Nov 23, 2007 | Epoxy on bottom of SMT component material has encroached onto the solderable termination, soldering the portion of the termination that is covered with the epoxy could be difficult. * Chipbonder used in the circuit board assembly process, where the chipbonder used to hold the component in-place during wave soldering that side has spread We're not real clear about what you're trying to discuss, because most capacitors are packaged in epoxy with a solderable termination on each end. But lets throw a couple of ideas at the wall and see what sticks. If this epoxy is: * From the capacitor fabrication process, where the packaging
Oct 22, 2007 | Hi Dave, The solder has tended to wet the component termination of Ag/Pd (chip capacitor) but has not wetted the pads, whereas the solder has wetted both termination & pads when using Ag/Ni/Sn finishes. Thks Solder wick on Ag/Pd termination
Oct 22, 2007 | Hi, Recently we have encountered solder wicking on components termination (total of 13 pcs of components on one pcb)with Ag/Pd finishes during lead-free reflow soldering. The pcb is LF HASL surface finish and LF solder paste composition is SAC305.We tried to increase the solder paste thickness & prolong the soaking time BUT solder wick did happen again. Then we change to Ag/Ni/Sn termination component,we got a good solder fillets. Can anyone tell us what is happening ? Thks Solder wick on Ag/Pd termination
Jul 24, 2007 | It sounds like the QFN component is not solderable. * Use ANSI/J-STD-002, Solderability Tests for Component Leads, Terminations, Lugs, Terminals, and Wires * Contact your QFN component supplier for help * Consider a more active flux, since you might be stuck with these parts
Jul 5, 2007 | ANSI/J-STD-002, Solderability Tests for Component Leads, Terminations, Lugs, Terminals, and Wires
May 29, 2007 | Is the component solderable per ANSI/J-STD-002, Solderability Tests for Component Leads, Terminations, Lugs, Terminals, and Wires?
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