Successful Endeavours - Electronics Designs That Work!

Electronics Design


Printed Circuit Board Assembly

Also referred to as a PCA, the Printed Circuit Board Assembly follows on from Printed Circuit Board Manufacture. This is where the components are placed onto the PCB or Printed Circuit Board and the electrical connections formed.

In this post I will focus on volume manufacturing techniques. We also make Printed Circuit Board Assemblies in house by hand loading very small quantities. This is appropriate for prototypes and Niche Manufacturing quantities.

To start with, let’s look at the 2 types of components we most work with. The first type is the Through Hole Component. These have pins that go through the PCB to make electrical connection. These components dominated PCB Assemblies until the 1980s when higher PCB loading density requires a change of technology. They are still widely used where mechanical strength, tall components, heavy components or high current levels are involved. An example is shown below with the connectors, relays, transformers and removable components as Through Hole with the Surface Mount Components toward the centre:

Through Hole Technology

Through Hole Technology

The second type is the Surface Mount Component or Surface Mount Device and the overall process is referred to as Surface Mount Technology or SMT. These devices do not require holes through the PCB to mount them and so can be placed closer together and it also improves track routing options because tracks can run on the other side of the PCB without having to avoid the through holes. An example of all Surface Mount assembly is shown below in close up:

Electronics Hardware

Electronics Hardware

 Printed Circuit Board Assembly Process

The infographic below was provided by Algen Cruz of Advanced Assembly in the USA. Algen also provided a brief explanation to go with it and I have added that as well. You can click on the infographic to view a larger version.

Printed Circuit Board Assembly

Printed Circuit Board Assembly

 “Design-for-Assembly (DFA), although not as well known as Design-for Manufacturing (DFM), needs to be taken into account during the design phase. And the first step in being able to design-for-assembly is to understand the assembly process. This infographic features this process by showing how a board goes from an unpopulated printed circuit board (PCB) to a final product, ready to be packaged and sent to consumers.” Algan Cruz

 

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2015 Successful Endeavours Pty Ltd.

Endeavour Awards 2015

This year we were finalists at the Endeavour Awards in the categories of Australian Industrial Product of the Year and IT Application of the Year. We didn’t win either category but the competition was pretty tough and I was pleased for ANCA for beat us for the Australian Industrial Product of the Year and also won the overall award for Manufacturer of the Year. The full list of winners are announced at the Endeavour Awards Winners 2015 official winners list.

Endeavour Awards Finalists 2015

Endeavour Awards Finalists 2015

It was a great night and a chance to share the evening with most of our team and a room full of people who are looking to be part of the solution rather than just contributing to the problem of being competitive in Australian Manufacturing.

Endeavour Awards 2015 Australian Industrial Product Of The Year

Endeavour Awards 2015 Australian Industrial Product Of The Year

 

Endeavour Awards 2015 IT Application of the Year

Endeavour Awards 2015 IT Application of the Year

If you have been following us then you will also be aware we are finalists at the PACE Zenith Awards in Sydney on June 11th in 4 categories. Wish us luck.

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2015 Successful Endeavours Pty Ltd.

Printed Circuit Boards

In our series on Electronics Design we have looked at the Electronics Design Process from Requirements Capture, Technology Selection, Component Selection, Schematic Capture and finally PCB Design of the  Printed Circuit Board including PCB Layout. Now we have a design and the Electronics CAD files to make a Prototype.

There are a number of steps involved in making a PCB and the following infographic provides an overview.

PCB Manufacture Steps

PCB Manufacture Steps

This infographic is courtesy of Newbury Electronics.

PCB Manufacturing Problems

That is a lot of steps. And there are things that can go wrong. The main pitfalls to avoid in the PCB Design Process are:

  • track widths too narrow
  • clearances between tracks are too small
  • acute angle entry to pads
  • component footprints have pins in the wrong place or the wrong size
  • component outlines are wrong
  • silkscreen or overlay over solder pads
  • via annulus too thin
  • mounting holes in the wrong place or the wrong size
  • PCB outline incorrect
  • PCB 3D profile doesn’t fit into the intended enclosure

And there are a range of issues that can affect the PCB Manufacturing Process. These include:

  • misalignment of drill holes to tracks to PCB outline routing
  • internal cut outs missed / not routed
  • over etching or under etching of the copper
  • incomplete plated through holes
  • poor surface finish
  • poor FR4 and copper bonding or moisture ingress leading to delamination

Maybe you are wondering how a PCB ever gets made successfully? This comes back to undertaking the PCB Design with an understanding of both electronics engineering design principles and the process capability of the manufacturer into account. And when you get it right, the final product can be pretty awesome. A good example can be found at this post about making a Fine Pitch PCB.

RGB LED Array Close Up

RGB LED Array Close Up

Next we will look at the PCB Assembly process.

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2015 Successful Endeavours Pty Ltd.

PACE Zenith Awards 2015

We have only just heard. You probably already know that we are finalists for the Endeavour Awards 2015 this year with 3 of our projects. Today we got the news that we are finalists in 4 categories at the PACE Zenith Awards for 2015. I’m sure at least one of you is wondering whether I spend all my time just applying for awards. The answer is no. I didn’t even apply for these. PACE saw the entries we put into the Endeavour Awards and decided they would also be good candidates for the PACE Zenith awards and asked me if it would be OK if they entered them for us. You can guess the answer I’m sure.

PACE Zenith Awards 2015

PACE Zenith Awards 2015

As a result, we are finalist in 4 categories for the 3 projects they nominated us for. The 4 categories are:

  • Water and Wastewater
  • Best Fieldbus Implementation
  • Power and Energy Management
  • Transport Power and Infrastructure

Both out IoT Platform (Internet of Things Platform) and Telemetry Host web hosted back end qualify for all of these, and the ABB CQ930 power factor correction controller and multi-bank or multi-stage capacitor controller supports the Power and Energy Management and also the Transport Power and Infrastructure categories.

The awards winners are announced at the PACE Zenith Awards dinner at the Four Seasons Hotel Sydney on June 11th 2015.

Wish us luck.

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2015 Successful Endeavours Pty Ltd

PCB Layout

After the Schematic Capture component of the Electronics Design  is complete, the logical connections for the electronics components have been determined. If the Electronics CAD package also supports it, you can add rules to guide the Printed Circuit Board Layout, also abbreviated to PCB Layout which we will use from here on.

The PCB provides both the mechanical support for the components and is many cases is a critical part of the circuit since the length of tracks, their thickness, their clearance from other tracks and the relative placement of components and tracks can significantly influence the final performance of the PCB. This is particularly true as power levels, clock speeds or frequency increases.

The Electronic Schematic defines the electrical connections between components, the value of components such as resistors, capacitors and inductors, the type of semiconductors used (silicon chips) and the connectors that take signals and power on and off the PCB. Each item on the schematic has to be linked to a physical shape that will go onto the PCB. This is done by assigning a footprint to the schematic item.

Schematic Symbol

I will explain  it works. The Schematic Symbol for an FT232RL USB Serial Interface device is shown below. This is arranged with the signals conveniently placed to suit logical connections and to make the overall Schematic easy to read and understand.  The signal name is shown inside the symbol boundary, and the pin number of the IC package is shown on the outside.

FT232RL Schematic Symbol

FT232RL Schematic Symbol

Schematic Circuit

So this  is the symbol for a single part, an IC or Integrated Circuit. The Schematic Circuit or Electronic Schematic shows the connections to the other parts of the circuit. Below we see USB connector wired up the the FT232RL IC and the power supply bypass capacitors. The logic level UART signals are shown at the top right. This section of the Electronic Schematic provides the logical connections for a USB serial interface.

FT232RL USB Schematic

FT232RL USB Schematic

PCB Footprint

Before we can do the PCB Layout, we have to associate the PCB Footprint each Schematic Symbol will use. The PCB Footprint for the FT232RL IC is shown below.

FT232RL PCB Footprint

FT232RL PCB Footprint

This is one of the 2 possible footprints for the FT232RL. This one is a 28 pin SSOP package.

Once each Schematic Symbol has a PCB Footprint, we are ready to do the PCB Placement.

PCB Placement

The first step is to create the outline for the PCB and its mounting points, then to place each PCB Footprint so it is in the correct place. For some components, such as connectors, there is a specific place it must go. For other components, there is more freedom to choose the position and there are groups of components that must be in a specific relationship to each other. An example of this are the power supply bypass capacitors which must go very near to the IC they are supporting.

An example of a completed PCB Placement is shown below. This is a USB to RS232 serial converter.

PCB Unrouted

PCB Unrouted

PCB Routing

Now we have the components where we want them, we turn on the autorouter and the PCB is finished. Sorry but I couldn’t help that. The autorouting features of most PCB Layout CAD software packages are never as good as doing it yourself. They can be useful for testing the ease of routing for a particular placement. There are a lot of manufacturing considerations that need to be taken into account and track size requirements, either for current carrying or voltage drop, can be hard to define from just the schematic. And example of this is the main system voltage such as VCC. In some parts of the circuit the required current is low so smaller track sizes are OK, whereas other areas need heavier tracks. It isn’t easy to define this at the schematic level because they are all the same signal or Net.

The PCB with the routing complete is shown below. The selection of track size is related to the current the circuit needs to carry. A good reference for determining the track size is provided by the standard IPC-2222A.

PCB Routed

PCB Routed

PCB 3D Cad Integration

It is also important to make sure the PCB will fit into a mechanical enclosure. Most modern PCB CAD tools, such as Altium Designer which we use, can create full 3D models of the PCB. Shown below is an example of just the PCB without the components showing.

3D PCB View

3D PCB View

So there we have it. A PCB taken from the completed Electronic Schematic through to a PCB Layout.

Next we will look at prototyping our new PCB.

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2015 Successful Endeavours Pty Ltd.

Fine Pitch Printed Circuit Board

This example is from a project coming to the end of the Proof of Concept phase. So we have done the Electronics Design and also completed the PCB Layout. I can’t tell you what it does, but you don’t really need to know in order to appreciate the technology. This is an example of a Fine Pitch PCB or Fine Pitch Printed Circuit Board. And even better, it was made right here in Melbourne, Australia.

Pictures first.

RGB Light Emitting Diode Array

RGB Light Emitting Diode Array

Above we have the top surface of a Prototype PCB that drives a 16 x 16 or 256 RGB LED array. The size is 25mm square for the LED Array. You might also have realised that this is a custom RGB LED display. The display is driven as a row x column matrix. This top side has the 16 row drivers.

RGB LED Array Bottom Side

RGB Light Emitting Diode Array Bottom Side

This is the underside with the 16 x 3 = 48 column drivers.

RGB LED Array Detail

RGB LED Array Detail

This shows some more detail where the Sea of RGB LEDs is sitting. They are in a staggered offset to reduce jagged edges on the image when it is displayed.

RGB LED Arracy Close Up

RGB LED Arracy Close Up

This final picture is a close up of the RGB LED array with a lace pin as a size reference. The RGB LEDs are 1mm wide and the pin head is a bit less than 1mm across. This is the smallest pin I could find.

Fine Pitch PCB Technology

Now for some technical details:

  • 4 mil track width (that is 0.1 mm)
  • 4 mil clearance (that is also 0.1 mm)
  • 0.25 mm via hole diameter

The Prototype PCB was manufactured by PCB Fast in Seaford. We use them for our Prototype PCBs because they still manufacture in Australia. And that is part of our focus, maintaining manufacturing in Australia. So I was very impressed with the work they did and thought this was a great way to show what they can do. I was also impressed with the spirit of adventure Kevin and Leeanne had in taking this one on.

One day I’ll be able to tell you what it was for.

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2015 Successful Endeavours Pty Ltd.

Schematic Capture

Schematic Capture is the process of defining the logic connections between different components in an Electronic Circuit. At the end of the process you have a diagram or Schematic of the circuit. That’s a complicated way of saying that it shows the connections between the selected components. We use Altium Designer as our EDA or Electronics Design Automation tool.

That is a lot of links but this is an important part of the process. Get this wrong, and you have a product that doesn’t work.

Electronics Schematic

Electronics Schematic

This the Electronic Circuit Schematic for a 5VDC Switch Mode Power Supply, also known as SMPS. It can deliver up to 0.5A and includes a number of novel features to reduce noise and ripple. The RC damper across D5 is one of these. The other is the 82R series resistor that limits the maximum current through the charge pump diode C14. The measured ripple is less than 1mVRMS.

I’ve gone into a bit of detail because this shows how effective Component Selection can lead to a great outcome. We started with the design objective of a non-isolated power supply to get a 5VDC rail for our circuit from the incoming 12VDC rail. I wanted an efficiency above 80%, low noise, small footprint and low cost. So we looked at a wide range of suppliers including some like Texas Instruments, or TI as they are usually referred to, who have tools on their websites that will select suitable components for you. In this case they didn’t have a suitable offering but Microchip did.

And the Schematic above is the result of the Component Selection process, review of the datasheet to get the circuit requirements for things like calculating the output voltage feedback divider (R10 and R12) correctly. And now we have our Schematic ready for creating the PCB Layout.

Altium

Altium – EDA

Altium have a comprehensive tutorial on the whole process using their tool at Get Started With PCB Design.

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2014 Successful Endeavours Pty Ltd

Component Selection

We have worked our way through Requirements Capture and Technology Selection. After doing some initial design work and deciding on how the circuit will work, you have to find components that you can buy on a reasonable lead time and at a reasonable price. This depends a lot on the expected production volume because if the volumes are low then you might not be able to secure the components you prefer.

For products Made in Australia, the typical production volumes are less than 5000 units per annum. Products in this category are niche or low volume products and are generally defensible internationally because of the special and targeted nature of the products.  But it does introduce a complication. You don’t have much of a bargaining position with suppliers. In this circumstance you often have to look at what you can buy and from who. This will involve looking at both local distributors and international sellers of components. An example from Element 14 is shown below for options for a 22uF 350V radial leaded capacitor:

Component Selection

Component Selection

And once selected, you might have to go through this exercise for each subsequent production run. Whereas much higher volume products can negotiate forward schedule orders and secure components in advance of their being required. So each product and production run needs to be handled according to your specific circumstances.

External events can also influence component availability. As an example, after the 2011 earthquake in Japan there were many components that were in short supply for up to 6 months.

This is one of the things you look for in a Niche Electronics Manufacture supplier, the ability to handle the component selection not only for the first production run but for subsequent runs.

Electronics News

Electronics News

If you want to explore this further, I have also contributed to an Electronics News article on this topic titled Electronic component sourcing: evolution and strategies. And for Online Components I’ve written a blog post expanding on Online Component Sourcing.

Online Components

Online Components

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2014 Successful Endeavours Pty Ltd

Technology Selection

Before we look at how to choose a Technology, what does Technology mean?

In very general terms, Technology is understanding how stuff works and how to get it to do what you want.

Technology Selection

Technology Selection

There is lots of different stuff available. In the case of Electronics Design this stuff is the type of Electronics you will use and how you will make use of it. The most important choice to make is to determine:

  • What functions will I implement using Electronic Hardware ?
  • What functions will I implement using Embedded Software ?
  • What functions will I implement using Remote Communications ?

In looking at the answers to these questions I also need to consider:

  • Cost to Design
  • Cost to Manufacture
  • Cost to support
  • Production Volume
  • Power Consumption
  • Performance
  • Time to market

In the process of Product Development it is often Technology Selection that can make the biggest difference.

Electronics Hardware

If there is no software involved, then this is the choice of which devices can be used to implement the design and how best to use them.

Electronics Hardware

Electronics Hardware

A recent example for us was the interface and power supply for a new GPS module for the Yarra Trams Passenger Information Systems. There was a problem with the existing GPS modules in scenarios where buildings either side caused the GPS module to lose position. And guess what you have a lot of in the central part of a city? That’s right, taller buildings. The Passenger Information Systems required an accurate GPS position to work correctly. So the GPS module had been selected including the use of dead reckoning to update the position based on the wheel rotation and the interface between this and the rest of the tram had to be designed including some level shifting to adjust voltage levels. We also manufactured the interfaces for them.

Yarra Trams VPIS

Yarra Trams VPIS

So that is an example of a project that required no Software.

But most of the time there will be Embedded Software involved. And there are several really good reasons for this:

  • Embedded Software costs less in manufacture – see Reducing Electronics Manufacturing Parts Cost
  • Embedded Software is extremely flexible
  • Embedded Software can test itself
  • Embedded Software improves field support, service and upgrade capability
  • The Electronics Hardware to run Embedded Software gets cheaper every year
  • Remote Communications is getting cheaper all the time

So today we spend 80% of our time writing Embedded Software in C and C++ to run on the Electronics Hardware we design through the PCB Prototype or even Production. This is known as an Embedded System.

For this typical project type we do as much in Software as we can.

Embedded Software

Embedded Software is the software that runs on the Electronics Hardware. Unless the product must be super Low Power Electronics, we will do everything in Software except for the power supply and physical interfaces to the outside world. But there are a few caveats:

  • signal filtering is usually more power effective in Analog Electronics than DSP
  • sleep and wake timing for high powered systems is often best done with external Electronics Hardware
  • you have to be able to select a Microcontroller that has the right combination of price, features and performance
Embedded Software

Embedded Software

Given the enormous range of devices available today you would think the last point was easily covered but a recent project we did ended up with only 1 possible choice in the whole world for the Microcontroller. Here is the requirements list:

  • Run from a button cell for at least 2 years
  • Has a beeper
  • Has an LED
  • Operated from -20C to +70C
  • After a period of dormancy, start flashing the LED and activating the beeper
  • Beeper frequency, on time, off time, number of cycles and gap time are configurable
  • LED on time, off time, number of cycles and gap time are configurable
  • Dormant period is configurable
  • Unit timing must be accurate to better than 1 hour per year
  • Unit price in 100K quantities must be less than US$1
  • Software must be protected from copying

The solution was an MSP430 based device from Texas Instruments with a 32KHz crystal. Actual cost ended up at US$0.71. And absolutely everything was done in Software.

Remote Communications

 With ubiquitous Internet enabled devices, knows as the Internet of Things or IoT, it is more cost effective than ever to add Remote Communications to products. This can have many benefits that reduce the cost of field and service support for a product and also makes possible features you could not have provided any other way.

Remote Communications GSM Modem Cinterion

Remote Communications GSM Modem

An example from a recent water metering project we undertook. This is a remote water dispensing system, also known as a Bulk Filling Station, that records who took water, how much water, when and where. The transaction is sent to a website via GSM modem and the Council can get the records to bill for the water without having to travel. It also means the tanker drivers don’t have to manually fill out log books and the Council don’t have to chase them for the data. Great savings there alone. But there were some extra benefits for us and the client that they hadn’t considered. These were:

  • Remote updates to the system application
  • Maintenance monitoring of batteries and valves
  • Regular check in to confirm the system was still operational

So if a new feature is needed, we can update the software and remotely distribute it the units in the field. Since these are currently spread over half of the east half of Australia that is an enormous saving. 

Internet of Things - IoT

Internet of Things – IoT

And we can also determine when the batteries need to be swapped out so that can be a preventative maintenance operation at a time of the Council’s choosing and not an emergency call out when a truck driver can’t get water. It is quite common for the first tanker to fill up before dawn when the solar charging has been off overnight and the temperature is at its minimum for the day. The worst timing from the batteries perspective so it just works better all round if we known for sure how the batteries are travelling by keeping track. It also means that if a solar panel is damaged the Council can see there is an issue before the system stops working.

And the regular check in allows the Council to know if a unit is still operational or not. A recent example from NSW was a fire fighting crew going to a water dispensing point to refill their tanker during a bushfire only to find it had failed sometime last winter and never been repaired. With Remote Communications you can avoid that and although it costs more to design,manufacture and operate (due to SIM costs) it can still reduce the overall cost of a system significantly.

So that is the general process. Once we have decided what we will do in Electronics Hardware, Embedded Software and how much Remote Communications to use we are ready to get into the Electronics Design in detail.

And of course, no post like this is complete without an input from Dilbert.

Technology Selection - Get It Right

Technology Selection – Get It Right

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2014 Successful Endeavours Pty Ltd.

Requirements Capture

Product Development is the core process your use when you have a great idea for a new product, or an improved version of an existing one. The very first step is to define what it is meant to do.

This first step is known as Requirements Capture. And requirements break down into 2 categories:

  • User Requirements
  • Engineering Requirements or Technical Requirements

These are related to each other and it is often useful to look at them in the right sequence. I’ll explain why later. Let’s look at what each involves.

User Requirements

This is a description of the product from the perspective of the user. It is written in the language of the user and describes what the product does and how it is used by the user.

User Requirements

User Requirements

We work with both technical and non-technical clients and the one thing they both have in common is that they can both write a document like this. It is also important that the focus begins with the user. Otherwise we can get carried away with the technical side of things and forget a real human being is going to have to use it one day. Concepts like Intuitive can have very different meaning to Engineers and the general public. So it is important to start with the user’s perspective.

Technical Requirements

This is what you end up with when you analyse the User Requirements through the lens of technology. We are translating from the user perspective to the technical perspective or engineering perspective.

Technical Requirements

Technical Requirements

As an example, the User Requirement might be that it complies with the relevant standards. This will translate to it passing C-Tick requirements for sale of product in Australia as part of the Technical Requirements.

Another example is that the User Requirement is that it must run off a pair of AA Batteries for 6 months. This then translates into a Technical Requirement that its average current consumption must be less than 0.57mA. If you are wondering how I came up with that then the maths goes like this:

An AA alkaline battery = 2500mAh so the average current consumption has to be 2500mAHr / (24 hours * 365.25 days per year  / 2) = 0.57mA.

That is the sort of analysis that is done every day by Engineers every day.

Requirements Analysis

The reason that it is important to look at User Requirements first is that we technical professionals love technology. And we love all the answers to the How questions. If we don’t focus on the What questions we can end up with a beautiful piece of technology that no-one actually has a use for. 

User Requirements = What

Technical Requirements = How

So there is quite a difference in how Engineers think compared to the rest of the world. For some other examples you might like to also look at these posts:

Does this work

Does this work?

Successful Endeavours specialise in Electronics Design and Embedded Software Development. Ray Keefe has developed market leading electronics products in Australia for nearly 30 years. This post is Copyright © 2014 Successful Endeavours Pty Ltd.

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