Successful Endeavours - Electronics Designs That Work!

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 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, lets 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.

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 the Printed Circuit Board or 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.

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.

Design For Manufacture

Electronics products almost invariably have a Printed Circuit Board , PCB, on the inside. This is one of the most common things we do, designing the Printed Circuit Board on the inside on the product. Now designing a Printed Circuit Board so it works correctly is one thing, but if you are going to make them cost effectively in volume then you have to consider the manufacturing options at your disposal. To achieve Low Cost Electronics Manufacture requires every aspect of the design to be considered. The following video covers the basic issues very well:

So the things to focus on are:

  • Use SMT as much as possible,
  • Reduce the number of components by using more highly integrated circuits,
  • Reduce the variety of components so the number of reels is reduced,
  • Ask the PCB loader about their standard panel sizes.  If you can adjust the PCB size to suit them then it will reduce their costs,
  • Work with component types that the PCB loader can handle
  • Work with components that you can buy in suitable quantities

Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years.  For more information go to his LinkedIn profile at Ray Keefe. This post is Copyright © 2011  Successful Endeavours Pty Ltd.

 

Electronics Design

Electronics Design is a very challenging area where reducing Time to Market, increasing Engineering Effort, constantly improving technology, tooling lead time and Agile Software Development methodologies all lead to rapidly changing requirements while the project delivery time frame remains immutable. Fortunately Electronics Engineers are up for a challenge.

At Successful Endeavours we use Altium Designer for our Printed Circuit Board Schematic Capture and PCB Layout.  So I was amused to see this video clip of some of the typical things that you have to overcome when doing an Electronics Design project.  Enjoy.

Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years.  For more information go to his LinkedIn profile. This post is Copyright © 2010  Successful Endeavours Pty Ltd.

High End Electronics

In the early days Electronics was hand wired on a chassis.  Some high end valve amplifiers still do this.  Check out:

Hayden Valve Guitar Amplifiers

Guitar Player reviews 6 hand wired valve amplifiers

Gibson valve amplifiers

Fender Vibro-King Custom

Torres amplifiers – build it yourself

Marshall Hand Wired Series

But of course this isn’t very compact.  For those who didn’t know, I am a guitarist and use a Carvin MTS3212 Master Tube Series tube amplifier which I still enjoy very much.  So when compact isn’t a priority and cost isn’t as important as the sound, then you go for this sort of amplifier.  This is another example of the trade-offs we discussed in the Project Priorities Perspective where it’s about Performance and Cost is the lowest priority.

Low Cost Electronics Manufacture

For Low Cost Electronics Manufacture however, there are other factors that come into play.  You want quality and you want it in a timely manner but the cost has to be low so that you have a decent profit margin.  So hand wiring is out because that is expensive.

Very well designed Printed Circuit Board PCB can produce excellent results and with the move to Surface Mount Technology SMT and the Surface Mount Device SMD the Component Loading Cost is also reduced as components are put in place by machines and there are no leads or tails to trim after soldering.  So this really helps with Electronics Manufacturing Cost and for at least the next little while will remain the way to go.

Another strategy for reducing cost is to use a modern Integrated Circuit IC because you can fit more functions into a more complex device and although it sometimes costs more for that individual device, you can reduce cost by removing other devices, reducing size and reducing loading and handling costs.

Reducing size reduces cost because you get more Printed Circuit Boards on a Panel and the cost of a panel in general is roughly the same ragardless of how many PCBs there are on it.

Emerging Electronics Technologies

But the future is approaching and there are some very interesting developments under way.  These involve Organic Semiconductors and Printable Electronic Circuits. Check out the following links:

printable electronics – a game changer

printable electronics on the rise

printable electronics to surprass $7 billion in 2010

Organic Semiconductors

Organic Semiconductors in a spin

I was particularly interested in the idea that the number 1 piece of equipment purchased by universities and Research and Development corporations conducting Electronics Research would be an inkjet printer!  And did you notice the convergence between these 2 Low Cost Electronics Technologies?

We are in for interesting times indeed when you can design your circuit and then prototype it on your printer.

Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years.  For more information go to his LinkedIn profile.  This post is Copyright © Successful Endeavours Pty Ltd.