Circuit Mechanix Mar 2016

Issue 1 March 2016 Circuit Mechanix The magazine for the PCB industry in the UKAfter PCB Design –What next?Knowing the AssemblyProcessZofz reviewedShedding light on whatyour fabricator doeswith your dataNews & more...

Circuit Mechanix Circuit MechanixMarch 2016 – Issue 1 Contents:The PCB magazine forthe UK printed circuitindustry.Contents P. 3Article:What should happen after PCB Design?Review: P. 4ZofzPCB P. 6Industry News P. 7Article: P. 9Knowing your PCB AssemblyProcessArticle:Shining the what yourPCB Fabricator with your data.Page 1 Circuit Mechanix – March 2016

Circuit MechanixMechanix MusingsWelcome to Circuit Mechanix, the first issue of a magazine focussing on the PrintedCircuit industry in the UK. This project has been rattling around in my brain for sometime and it was at the beginning of this year that I decided to just go for it and make ithappen.Circuit Mechanix is aimed at being a useful, practical source of information for engineersand technicians working in the PCB industry. There will hopefully be an issue everyquarter, which will hopefully generate interest from other individuals and companies. Ifyou want more information, feel like you can contribute in some way or if you’re acompany that wants to see your name in Circuit Mechanix then send an email to:[email protected] that the introductions are out of the way, let’s get down to business. What’s the firstissue about? This first issue is about that tedious but key part of the process betweendesign and manufacture. It’s an area that’s rarely covered and yet can be the source of somuch pain. The articles in this first issue of Circuit Mechanix are should help guide thereader the obstacles by pointing out what can go wrong and how to overcome .On a more light hearted note, there’s the introduction of Numptyz – a cartoon striplooking at the ironic and satirical side of the workplace. It’s an old format, but with newcharacters with twist of contorted ‘common’ sense. Page 2 Circuit Mechanix – March 2016

Article: What should happen after PCB design?The PCB design is complete, all the 1) NetlistDRC checks are done. Hours of pouring 2) Component positions dataover every part of the design by you 3) Assembly drawingsand your colleagues have been made 4) Build instructionsto make sure the latest electronic baby 5) Important component informationis as good as it’s going to be. What 6) Other special requirementscomes next?There are many, many articles about Designers and engineer’s know theredifferent aspect of the printed circuit are times when things have gone wrongdesign process, or the bare board because some key information isfabrication do’s and don’ts. Very little is missing. It’s unreasonable to expect thewritten about post design, this could be companies making our boards to noticebecause it’s the boring bit that no-one the unusual or to mind read ourwants to talk about because it’s as intentions. The good companiesmuch fun as being poked in the eye. sometimes pick up on those things thatBut capturing design intent at this point seem strange and ask for clarification,is key, or the you could be doing it but relying on this is dangerous.again sooner than you think.Let’s assume for the purpose of making What’s the simplest way of finding outthis a little easier to swallow that the what’s needed? Do what mostbasics like silk colour, solder resist and engineer’s hate – pick up the phonestack up etc etc are all documented on and talk to them, if that’s too painfulone of the design layers as they should there’s good old email. The key thing isbe and the library components are tried to ask them and find out.and tested. All the gerber files havebeen generated and are sitting there. Circuit Mechanix ©2016What other documentation is needed?Page 3 Circuit Mechanix – March 2016

Review: ZofzPCB – Enhancing the design ProcessPCB’s are becoming more complex and Unlike other 2D gerber viewers,a critical part of almost all modern ZofzPCB lets the designer see thesystems. Design tools have a huge PCB’s manufacturing data in a 3Darray of features to get the design how format, it enables the designer to splitthe designer wants it. Verifying the board apart and view the innermanufacturing information against the layers and how they’re connected.design is critical as mistakes can occur More importantly, by importing an IPC-in the translation on rare occasions. It’s D-356A netlist from the design intosurprising that EDA vendors haven’t ZofzPCB an error check of the gerberaddressed this gap in the process. files can be carried out. While gerber errors from design systems are rare,Recently I was introduced to ZofzPCB – they do happen and the cost in lost timea gerber viewing and verification tool and materials is expensive to say thethat I hadn’t heard of before. least.Page 4 Circuit Mechanix – March 2016

ZofzPCB review continued…Using the netlist data, ZofzPCB cangenerate an accurate view of thefinished PCB. It’s guesses thecomponent likeness from the netlist, socustom components are notrepresented well. I haven’t even got tothe best part yet – ZofzPCB is free!ZofzPCB has been created by Rafal What Rafal has created is anPowierski, when asked about his independent tool that can allow thereasons for creating a program of this verification and examination of thecomplexity for free he said: actual PCB manufacturing data in a“I have an interest in physics. I wanted way that hasn’t been available before. Ifto build an electromagnetic simulation there is comparable tool in the marketprogram that could check PCB designs that has this kind of functionality it’s notincorporating many of high speed widely known about and probablyinterfaces, like DDR2, HDMI and PCIe. carries a hefty price tag.My previous experience was Having tested this and found that itSDRAM running at 75MHz. This picked up errors between the designtechnological step was terrifying, so I and gerbers, ZofzPCB can easily saveneeded a PCB high-speed test/check hours fruitlessly checking gerbersprogram The planned to get the manually on 2D gerber viewers. It’s also3D PCB information from the PCB fun and interesting playing with theGerber data. With painting or different 3D view functions and seeingoverlapping drawing elements how all the inner layers of a design\"flattened\", that is converted to simple connect.positive shapes. The PCB needed to bedisplayed, that was an opportunity to do To try out ZofzPCB for yourself visitsomething in Direct3D. The 3D Gerber https://www.zofzpcb.com hand have aviewer was a first step, which is already look. Try it out and see what you think,a useful standalone application. I while it won’t verify your design isplaced it on-line, for free download. For correct, it will give you a greater idea ofthe next step, the 3D EM solver needed what you’re really designing and theto be created.” confidence that what your design tool has generated is what you designed in CAD. Circuit Mechanix © 2016Page 5 Circuit Mechanix – March 2016

Circuit MechanixIndustry News: Anglia Circuits have recently invested in a Bacher auto alignment printing machine. Improving their registration capability significantly. Epoxy filling of via is now available for PCB’s in prototype quantities. www.angliacircuits.com SnapEDA have just launched an experimental plugin for Eagle users, allowing easy access to SnapEDA from within the Eagle PCB design tool www.snapeda.comSionics Sionics are working towards the ISO13485 approval for Medical Devices. A positive outcome is expected within a few months. www.sionics.co.ukPage 6 Circuit Mechanix – March 2016

Article: Knowing your PCB assembly processIt’s always a time of mixed emotions Handling – How well setup is yourwhen a new batch of PCB’s arrives on subcontractor to handle ESD (Electroyour desk, fresh from the subcontractor. Static Discharge) and moistureExcitement of testing the design that’s sensitive components? Are therehad time, blood, sweat and tears put equipment and controls in place tointo it. Hoping they work after all the handle them? Controlling static is oftentime and money that’s been spent on regarded as unnecessary, however it isthem. Knowing the assembly process a real risk to components. The samecan give a designer or engineer greater applies to moisture sensitivity, whichconfidence in the finished boards. components are rated as moistureDifferent aspects that can be sensitive in the design? What impactconsidered are: will this have?Paste Screens – How the paste Reflow – What reflow process doesapertures are defined in a design can your subcontractor use as standard?be important to the assembler. Find out Normally this doesn’t matter, howeverhow the paste apertures are used in the some components can be damaged bysolder screens. What often happens is vapour phase reflow processes. Notthe paste aperture in the gerber files for only is a good knowledge of thea PCB will be a 1:1 representation of assembly process required but anthe pad and this is used by a separate intimate search of componentstencil fabricator to make the paste datasheets is sometimes necessary.screens. Check what a subcontractor Checking individual assemblydoes though, an incorrect assumption requirements of the components iscould lead to the incorrect quantity of often hard as the information that’spaste being applied. important is buried deep in the datasheet on page 12 in small text which isn’t highlighted. Continued…Page 7 Circuit Mechanix – March 2016

Knowing the assembly process Check and make sure this is the case,Continued… do they inspect a sample or each PCB?Cleaning – What kind of cleaning Finding and curing a short or dry jointprocess does your subcontractor use as you can’t see is difficult to say the leaststandard? How a PCB is cleaned can and many component packages haveagain affect components, check your connections underneath the componentdatasheets. It’s also not a great idea to body. Your subcontractor should beclean components like transformers as able to check this with some kind of x-drying them can be hard and will have a ray or specialist visual equipment.negative effect on safety clearances (ifit’s a safety / isolating transformer). Depending on the product type and theWith the cleaning process there should PCB being made there could be morebe a drying process as well, making that needs to be known. The point is –sure it’s sufficient to completely dry out know your subcontractor, know whatthe board this is especially needed if they’re doing and as much as possibleusing Rogers materials. tell them what is needed.Inspection – AOI (Automatic Optical Circuit Mechanix © 2016Inspection) is employed by mostmedium to large sub assemblycompanies.Page 8 Circuit Mechanix – March 2016

Article: Shining the light on what your PCB Fabricator does with your dataAfter the design process is complete Ask them to make a list of the changesand the fabrication data, is generated they make. With the best will in theand checked (I’m sure everyone world the design rules the design isreading this checks their data before checked against are often not set up togiving it to the fabricator) it’s sent to the the manufacturers constraints. This kindfabricator and after a few days some of information will help you understandPCB’s arrive back, just like the PCB’s what they need better.that were designed. It’s simple right?But what has the fabricator done to / Most of the time PCB’s are supplied inwith your data? panels, how they are aligned can cause issues with your product (where theHave you asked for your fabricator to breakouts are for example) or possiblycheck the gerbers against a netlist? the manufacturing process. Having a review on the panel data and possiblyIs the panel data reviewed before having the assembler look at it, (if theproduction commences? design complexity demands it) can help smooth out the assembly process.Why is it even important? Like all thesethings, it’s impossible to know until the If you’ve provided your fabricator with aquestion is asked! netlist to check the gerbers against, have you checked to make sure theyThe next time PCB data is sent to your can read it?fabrication company why not ask them Is your fabricator carrying out thisa few things: check? Continued on next page…Page 9 Circuit Mechanix – March 2016

Shining the light on what your PCB Time and money may be saved if barefabricator does with your data – board test is deemed unnecessary, butcontinued… imagine the lost time and money is there’s an error on some or all of theThere is normally some kind or test populated boards. Really it’s a falsereport generated when this process. economy.Getting the results of this ensures thatnot only can they read the netlist and The next thing that’s interesting to lookyou’re generating it in the right format, at is plated through holes. The hole sizebut that it’s being carried out. given in your design – is it treated as the finished hole size or the drill size?Asking the fabricator to do this is often Surely the difference doesn’t matter? Inneeded as sometimes the principle of ‘if a hole for a large transistor this isit’s not asked for it’s not needed’ is certainly not going to make muchused. difference. But a small hole for a fine wire or lead may end up being smallerThe netlist will also help give the that expected as the plating can reducefabricator the data they need to test the the hole size by 0.1mm. Sometimes thisbare boards. But of course, is this counts.carried out? If it’s not, faults in bareboard test will not show up until the Knowing this kind of information aboutboard had been populated and testing how your fabricator works will help ais being carried out. If it’s being asked designer enhance their designs byfor, make sure that a copy of the test enabling them to work with thereport is included with the delivered fabricator more effectively. Also goingPCB’s. through the post design manufacturing review shouldn’t take as long as itTime and money may be saved if bare sounds, but it could save a mess upboard test is deemed unnecessary, but and they cost far more time and money.imagine the lost time and money isthere’s an error on some or all of the Circuit Mechanix © 2016populated boards.Interested in seeing your company name in here, or doing something you want to tell everyone about?Email [email protected] for more information.Page 10 Circuit Mechanix – March 2016

Circuit Mechanix Next Issue: Next issue out in June 2016 - What’s going to be in it? Articles: Designing flex and flex rigid PCB’s - The practical point of view. Presenting data to your fabricator. Review: Mobile apps for engineers and technicians. And more…Page 11 Circuit Mechanix – March 2016