Circuit Mechanix on PUBHTML5

This is just a short blog post to let everyone know that Circuit Mechanix is now available as an online flip magazine from HTML5, I’ve moved this from MagCloud as I felt the magazine was slightly better. MagCloud was also confusing and implied you needed to buy the magazine.

Visit www.PUBHTML5.com and search for Circuit Mechanix to find all the magazines to date available for download.


PCB Mechanic

 

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Snap EDA & TE Connectivity

TE Connectivity releases over 25,000 new digital models in collaboration with SnapEDA

Engineers can now easily design-in a wide variety of components with free symbols & footprints

The idea came from Natasha Baker (pictured right) who started Snap EDA to address the market of delivering PCB library components to engineers quickly and cost effectively.

 

The website gives a library of parts in it’s database, a design hub from semiconductor manufacturer’s, a diagnostics tool for checking library parts and a community to share key topics with other engineers. natasha-baker-e09d3bd73a63

With this new collaboration, designers can now download free printed circuit board (PCB) footprints and symbols for TE components instantly, saving them days of time so they can focus on product optimization and innovation.

With this new collaboration, designers can now download free printed circuit board (PCB) footprints and symbols for TE components instantly, saving them days of time so they can focus on product optimization and innovation.

 


 

Screenshots of SnapEDA working with the new TE Connectivity library can be seen here and the slick, easy functions will make integrating part into libraries much easier than traditional methods.

 

1 - TE Symbols _ Footprints on SnapEDA2 - Start Designing with TE Connectivity Parts3 - Search thousands of TE part models on SnapEDA4 - Free 3D models from TE.com

 


 

The models are compatible with Altium, OrCAD, Allegro, Eagle, PADS, DXDesigner, and KiCad.

Snap EDA was founded by Natasha to bring the PCB library to the designer and help them save time creating library parts.

Progress on increasing SnapEDA’s offering has grown rapidly the collaboration with TE is the latest collaboration which also included offering footprints to Menotor’s PADS tool last year.

Have a look at the website – www.snapeda.com have a look and see if they can transform library creation for you.

 

© Circuit Mechanix 2018

Wrong Footprint – PCB Design Code Brown

In the world of electronics there are many, many ways to goof up. Sometimes when things go wrong this is called ‘code brown’ when the realisation of what’s gone wrong hits that well… I don’t need to explain.


 

The experienced PCB designer knows well from bitter experience that creating a new PCB component / footprint is a risk that comes with the territory of the job. Every human operation is open to error and there’s nothing worse than creating a component in a PCB design that’s been made wrong or has been given the wrong footprint.

Whenever it happens it often starts with a call or visit from the company or team assembling the components onto the PCB. the line goes something along the lines of:

“We’ve got a part that doesn’t fit!”

You get that rising feeling of dread, pulling up the design the tool seems to take forever to load. Looking at the part a little prayer is said, clinging to the hope that the wrong part has been ordered or that last letter at the end of the part number is incorrect at least.

Then it hits. You’ve assigned the wrong footprint onto the component. An alternative isn’t available and there’s going to be that awkward conversation about re-spinning all those PCB’s again.

It’s the worst feeling in the world!

Only a robust review process and diligent people can hope to stop this kind of thing happening and no process is perfect. But this isn’t an excuse to have no process, all too often the design process neglects parts checking, neglects design reviews and at some point it will cost because with the best will in the world no PCB engineer is perfect.

Don’t have time for design and parts reviews? Maybe… but do you have the time and money to correct it when it goes wrong? I bet not.


PCB Mechanic
©CircuitMechanix 2018

 

The PCB Mechanic – Datasheet Torture

Datasheet torture – what is this? Anyone who has tried to create library parts will know exactly what this is about. A classic example is this Micrel component, where the manufacturer is trying to convey the required footprint information to a PCB designer or engineer who need to create an accurate PCB footprint for their design.

Have a look at it, at first it seems simple but on closer inspection we see that they’re trying to convey some kind of L shaped land and then the hatched area seems to denote something. But we don’t know what.

Datasheet

This means that the engineer really isn’t being informed well. Then look even closer at the bottom, the wonderful disclaimer that basically says, follow these instructions but don’t blame us if it goes wrong.

I’m sorry, but this is crap! The part manufacturer is really taking no responsibility here and let’s be honest isn’t doing a good job of trying to make life easy for the engineer. Sure they’ll take your money if you buy the parts but we’re not going to help you design it in and don’t cry to us if it goes wrong.

That’s bad business and bad service.


 

There’s also a big problem when we arrive at the situation of large IC’s with 100 plus connections. The problem? The pin assignments. The order that the pin details comes in often seems pretty random. I hear the echos of “What sadist wrote this datasheet?!?” from one engineer who was trying to decipher the pin arrangements of a BGA. My only insight was that it might make sense at the die level – totally useless and meaningless for the PCB design level.

I’ve said before in Circuit Mechanix that component technology is driving PCB designers and fabricators to design boards that are increasingly advanced, the problem is that the manufacturers of these devices are NOT helping engineers to design in these parts properly. Fanout information including the right drill patterns is often not included in datasheets or is poor. Key information isn’t clear or is misrepresented and this is leaving engineers and designers bewildered.


 

My message is clear and I’m sure I’m not the only one who would echo this: Component manufacurer’s sort your act out and sort your datasheets out! Help us design these parts properly into products but giving us good information because with a few exceptions most of you are doing a terrible job at this!


PCB Mechanic
©CircuitMechanix 2018

 

PCB design tools – Selecting the you’re going to curse!

It’s a common question when meeting a group of PCB designers  – “What tool do you use?” There then follows a line of conversation of justifying the choice of tool, maybe highlighting the fact that it wasn’t your choice then after a short discussion on what you’ve managed to achieve. After this is the inevitable list of things that every designer does not like about their design tool, the things that have brought them to such frustration that they’ve been pulling their hair out.

Every PCB designer has something to curse about the PCB design tool that they use. It never, ever runs as smoothly as the designer wants it to all the time. So that begs the question – is the wrong design tool being chosen or does the ‘perfect’ solution not exist?

Let’s get one thing out of the way first – there is no silver bullet in PCB design tools, every single on one of them has their strengths and weaknesses. So the trick (is if the chance arises) to choose the PCB design tool that’s going to suit your needs best.

I’ve been fortunate enough to get some thoughts on this from Jim Patterson, Electronics Group Leader at Evonetix:

So… how to choose an EDA tool? Well, who are you? Start-up with small aspirations where you can rely on contractors? Or do you have big growth plans and a desire to keep control of your design data entry? Are you a medium to large company looking to re-evaluate how effectively you manage your PCB development process? No doubt there are many more situations. I also don’t think there is a one-to-one mapping between your corporate situation and PCB EDA tool. I genuinely believe the most effective approach is to commit to a tool and get on with getting good at it and putting in appropriate procedures to ensure quality design data goes out the door.
Another thing that might influence your choice is the availability of contractors/design-houses who can use your tool of choice. You don’t want to pay to train them as well as do your design.
Enterprise vs Independent: if your business has no plan to make PCB design an important part of the company’s ability to create revenue then there is little point going for the big guns – they require more IT maintenance, more training and more money (eventually). On that last point – it is common to for a start-up to be offered the enterprise tools for free while the get set up. If you go for that be sure you are either financially ready for a big hit around the corner or are well prepared to drop the tool and switch to the competition at short notice.
Thoughts on individual tools…
Altium Designer: most bang-for-buck. Huge number of features backed up by being pretty intuitive to use. I don’t like how “infinitely” configurable it is. Maybe if they focused more on a single usage model it would operate more consistently and lead to fewer utterances of “OH FOR GOD SAKE ALTIUM”. I get the feeling it probably doesn’t scale as well to enterprise level PCB design (i.e. PLM, multi-site design entry, multi-person editing, advanced DFM analysis).
Cadence OrCAD: awesome layout tool, meh schematic entry, relatively open pricing, cheap. I really like the layout tool (PCB Designer) and you can get it very cheap (£549 for a 1y rental, £5500 for top-end options & perpetual license: http://www.parallel-systems.co.uk/pcb/). Should scale up to Allegro enterprise tool relatively easily if you need to.
Mentor PADS: Recently split into 3 types which means it now spreads across the Altium price/features range. Hints at $5k – $18k cost across the option range (http://www.eetimes.com/document.asp?doc_id=1326450). Not used it myself, but the top option now offers a lot of the high-end (xpedition) features. Should scale up to Xpedition enterprise tool relatively easily if you need to.
Honourable mentions…
Pulsonix (http://www.pulsonix.com/), Easy-PC (http://www.numberone.com/) and Design Spark (https://www.rs-online.com/designspark/pcb-software) are all flavours of the same tool. I’ve enjoyed using Design Spark for uni/PhD projects.
I’ve read good things about DipTrace (http://www.diptrace.com/) – very good value for money.

My Own Search

With this in mind a few years ago I was part of a discussion deciding what PCB design tool the company was to use in future. The current tool had failed and it was felt that it was time to move on.
My role in this was to bring the PCB tool options to the group so that the options could be discussed, looking back the summary of what we decided was interesting in many ways. Having had different experiences of the tools and had some demonstrations and quotes this is what was decided:
1) Mentor Pads:
Some of the engineer’s had experience in using Pads, so it was not an unknown. While the tool was felt to be capable it was costly, especially if extra options for 3D visualisation were required. As this was felt to be important and that any ‘extra’s were going to be costly, it was decided that this wasn’t the right way to go.
2) Orcad
There was minimal team experience with Orcad, it was also seen to be a very
Mentor-esque option as only the year before having upgraded to the latest version I was told that a library manager would cost extra. That was as far as Orcad got.
3) Cadstar:
No experience in the team whatsoever with Cadstar, to the point that it wasn’t even discussed as an option.
4) Pulsonix
Pulsonix had been trialed earlier in the year for it’s flex rigid capability, it was the only tool that would import designs and libraries from our current design tool  and came at a good price.
A demo left us feeling like it was a good option, but there were a lot of features that were ‘about to be released in the next version’. It would probably have done the job, but there was the feeling of the customers being guinea pigs for the product.
5) Altium
Altium’s success over recent years, the balance of cost against capability was very attractive. The vault was seen as a very effective tool for documentation control and the options for configuration were obviously huge. 3D integration and some mechanical and simulation capability was built into Altium as well as document release.

Which was best?

Even after deciding that Altium was the tool to use, there was the realisation that it was not going to be perfect. There were bugs, issues and it wasn’t perfect. We hadn’t found a silver bullet – BUT we knew that moving to Altium was going to be able to give us another level in our electronic design capability.
That is why PCB engineer’s tolerate the tools they use, if the tool has been chosen well if it fits into how the company runs it’s going to do the job it needs to do and do the job the electronic and PCB engineer’s demand. What suits one person or company doesn’t always suit another, the only thing that is certain is that at some point the design tool will be, for one reason or another – cursed!

PCB Mechanic
©CircuitMechanix 2018

Circuit Mechanix – Moving Forward

I know that the following on Circuit Mechanix isn’t very big but for those of you that may have been following it probably hasn’t escaped your notice that there hasn’t been much activity this year. Both the magazine and the blog have been a little lacking on fresh material.

So I can try and address this I’m goign to change the way things have been done. Rather than the magazine feeding the blog, the blog will feed the magazine. I’m hoping that this is going to keep fresh content moving into the Circuit Mechanix site and then onto the magazine.

As usual if there are any requests for information or content or any offers of contribution then I would be more than willing to accommodate them.

Thank you for your continued support.

Circuit Mechanix

 

NPL Soldering Defects Database

NPL Defects Database

The Soldering Defect Database is a freely accessible resource from the National Physics Laboratory website:

Defects Database

This little known resource is a fully searchable database of soldering defects with pictures, and information about the causes and solutions of each problem. Once signed up not only is all the information available but the database can be added to with any findings a user wishes to add.

This is a truly a brilliant resource and I can’t think of how many occasions this could have been of use in the past. Have a look, get involved and make sure to pass it onto your colleagues.

Circuit Mechanix Apr-2017

The PCB Mechanic – The UK PCB industry and facing the challenges of the future

PCB Mechanic

 

PCB fabricators in the UK are facing the challenges of being able to make the PCB’s that the designers need to accommodate these modern packages. This is no easy challenge, fabricators based in Asia and other European countries are providing their customers with advanced capabilities that not long ago were not possible. Not only do these fabricators have the capability, but the manufacturing costs cannot be matched equivalent fabricators in the UK.

Electronics are advancing at an ever increasing rate and this rate has no sign of abating. Integrated circuits are being developed all the time with increasing speeds, functionality and higher densities than were available before.
This gives engineers the components they need to create products with more functionality in a much smaller form factor than has been possible before. No other market shows more evidence of this than the smart phone and tablet market. These supercomputers in our pockets were inconceivable in such a compact size fifteen years ago.

Chip packages come with far more, smaller connections, whether they’re balls, pads or pins in a much more compact package. In for UK fabricators to win business to serve this insatiable demand for smaller and better electronics, they need to be able make the boards that are being designed today and be looking forward to the designs needed in the years to come. It doesn’t seem that long ago that a track and gap of less than 0.2mm would be the exception rather than the norm, but modern electronics has ended this forever.

It seems however that many UK fabricators are struggling to realise this and are not investing enough to keep up with the rate of change.

The high density PCB packages of today are forcing designers to use track and gaps of less than 0.1mm or copper filed via in pad, or via sizes of 0.1mm just to be able to route connections out to the rest of the circuit. BGA’s aren’t the only issue, dual row and other leadless packages where the pins are 0.5mm apart or less are forcing designers to make tough choices about where they place the compromise in their designs.

BGA’s aren’t the only issue, dual row and other leadless packages where the pins are 0.5mm apart or less are forcing designers to make tough choices about where they place the compromise in their designs.

There aren’t many PCB fabricators left in the UK and only a handful are able to compete with the capabilities that offshore companies are able to give. The reality is that there is a tough job ahead to catch up and keep up and many PCB fabricators haven’t advanced their capabilities in over 10 years. This is an age in technology terms. The UK cannot possibly compete on cost with offshore manufacturing, but if they can’t do at least the same or better, there is no way to compete with the offshore fabricators.

Simon Farnell The PCB Mechanic

This article was features in the March ‘What’s new in Electronics’ newsletter:
http://wnie.co.uk/library/uk-pcb-industry-facing-electronics-challenges-future/

Flexi PCB’s and making something wobbly like it’s not

Just like standard rigid PCB’s flexi’s and flex rigid PCB’s have to have components assembled onto them to make them useful in a circuit. However unlike rigid PCB’s flexi’s are well… flexible.

The flexible nature of a flexi is it’s strength in the field, but during manufacture causes nothing but problems! There are ways and means around this and that’s what’s going to be discussed here.

Part of the issue is that the fabricator needs to make the FPCB’s on a rigid panel that the assembler can accept and work with. In prototyping volumes this isn’t likely to be an issue, but if thousands or millions of FPB’s are to be made then there has to be a solid working interface between the fabricator and assembler to make it work optimally.

PCB’s are usually more efficient to assemble in larger volumes on a panel. Flex panels tend to have less circuits on them and a smaller as the panel, even with stiffeners are often weaker. If there are components on both side of an FPCB, then making the panel so that solder paste can be deposited onto the board also needs considering. Often stiffeners or panels sit above the FPCB, making paste deposition impossible. It’s for this reason that good communication is needed between designer and fabricator to get every detail right

Be warned – making a the same design in different companies can result in different approaches and things going wrong. Because there is so much more for the manufacturer to understand than rigid PCB’s like stiffeners, panels etc, there is more to get wrong.

Layer stackups are also something to watch out for, especially between different fabricators and sometimes different factories within the same company. The differences are often very minor and irrelevant but even small differences can have an effect on a design – especially in high speed circuits.

Good fabricators will highlight these changes and give their best alternative so keeping track of what’s being built can be done.

The nightmare every PCB designer needs to consider in FPCB’s is how any components will be assembled onto the board. If the flexi is on a panel this is a good first step, areas where components need to be assembled onto them will need to be secured or assembly will be impossible.

Fabricators will have tape or some other kind of way to secure
Component area’s on FPCB’s. Identify these area’s in the output data and label them to make it easier for the fabricator to identify these areas and process them accordingly. Doing this will make assembly far easier – the only problem after this might be peeling the flexi away from the panel without damaging the components or their solder joints.

It’s for this reason that assembling components onto FPCB’s should only be done when it absolutely has to be done.

If you’re not putt off yet, you should be – no one said it would be easy!

Circuit Mechanix © 2016

Designing Flexi’s and Flex Rigids – What’s Involved?

Flexible and flex rigid PCB’s are offering solutions to product designers that are not just a luxury in this day and age but a necessity. The technology itself isn’t that new, flex PCB’s have been around for over 30 years. But in today’s world of extremely compact and high speed connections often there is no choice but to use them over conventional electronic assemblies using wired connections to connect between PCB’s and these are to large. This is the main reason for their increased use in the last 10 to 15 years.

But how does the PCB designer go about designing a flexi or flex rigid PCB with components on it and how can the design be made easier to manufacture?
The basic Do’s and don’ts around flexi circuits we can get a picture of what’s involved and why:

a) To avoid the flex material tearing in manufacture or use, put as large a radius as possible on all internal corners.

FCB1

b) Via’s should not be placed in bend area’s as they can crack.

FCB3

c) Tracks running through bend areas should be routed at 90º to the bend.

d) Tracks on flexi’s ideally should be routed with filleted corners to stop them breaking during flexing.

e) Copper pours on flexi’s should ideally be hatched, especially in bend area’s. Because of stresses in the solid copper pour fractures are likely especially during flexing.

FCB2

This simple guide gives the designer a good basis on which to design flexi PCB’S (FPCBs) well. The challenges don’t end here though. Ideally an FPCB will have stiffeners under areas where components are going to be in the circuit. You can bet there will be times where some bright spark will decide for one of many reasons that the FPCB will have components and no stiffeners.

This is not an easy task and the designer is likely to get the task of working out how this can be done. This usually means working out what kind of stiffening frame can be used with the fabricator and assembler and sticking the FPCB down.

The reason for sticking down and FPCB for assembly is clear when it’s understood that the copper on an FPCB is giving at least as much structural rigidity as the substrate itself. Stresses in the copper push and pull the shape into interesting and often unwanted shapes. Assembly would be impossible without sticking the FPCB down to something rigid.

Added to this the copper finish isn’t very durable and can crack if flexed. Keeping these component pads away from bend area’s is necessary to ensure they survive through to assembly, but if it putting the component in a bend area can’t be helped then sticking the FPCB down to secure it is another reason why sticking it down is not be a bad approach to use.

As always it’s never a bad thing to engage manufacturer’s in the design stage and with flex this is even more important, even if only at first until all of the design aspects are better understood.

© Circuit Mechanix 2017