According to Wikipedia the world market for bare PCBs exceeded $60.2 billion in 2014 and in 2018, the Global Single Sided Printed Circuit Board Market Analysis Report estimated that the PCB market would reach $79 billion by 2024. At the same time the United Nations estimates that 40 million tons of e-waste are produced every year and the OECD estimates between 20-50 million tons a year.
The traditional method of electronic product construction is the PCB which in essence is the permanent or semi-permanent attachment of electronic components or modules to thin metal tracks running over the surface of one or more layers of board. It is therefore productive to ask if this form of construction is the root cause of part of the mountain of electronic waste now causing a major world problem.
The central problem which links PCB construction to electronic waste is that the permanent or semi-permanent soldering of components or sub-assemblies to a PCB makes repair, upgrade, disassembly or reuse difficult or impossible. Hence products are not repaired or upgraded and components and sub-assemblies are not disassembled or reused, they are simply chucked on the ever growing and problematical waste mountain. How can we mitigate this ?
A further consideration relates to the Mean Time Before Failure (MTBF) and the Residual Value (RV) of the product or disassembled parts. Individual components have individual MTBFs however the MTBF of a product often translates into the MTBF of the shortest life component when the costs involved in skilled test and repair mean that it is uneconomic to diagnose faults. The RV of a non working product is negative if it is confined to land fill (there is a cost to land fill). The RV of any repaired or upgraded product is related to its new MTBF or mean time before further repair or upgrade. The RV of any recoverable component or sub-assembly is related to the MTBF, and to the nature and range of alternative uses for the part. The longer the individual MTBF’s and the greater the value, and range of alternative uses, the greater the RV of the sum of the RV’s of the components or sub-assemblies. So if we want to minimise the cost of electronic waste and maximise all residual values – is there a way forward ?
If we look at the bigger picture and see what has happened to the interconnection of individual electronic products we can start to see what may be on the horizon. In the not so distant past individual electronic products used to be connected by metal wires. CD players used to be connected by speaker wires to speaker arrays. Computers used to be largely connected by network wiring systems (e.g. Ethernet). Disk drives used to be connected to computers by means of multi signal pathway BUS connections. Recently in all these examples the hard wire is being supplanted by new technologies centred on high speed serial connections often over wireless or optical communications. Technology is eroding the need for the all the metal wires.
We need to ask what are the implications of these existing trends at the macro level for the micro level of the PCB. Do we need these repair, upgrade and reuse unfriendly PCBs with lots of components firmly soldered to old fashioned metal tracks? Perhaps not, and if we look at the changing nature of modules and components we can start to see that the PCB market is already endangered. Already at the individual component or module level, on-chip wireless and optical high speed communications are becoming available. No longer do these components need to be soldered to large numbers of metal tracks.
We can envisage that all that may be necessary is that these new components need to be supported on some form of modular frame replacing the support function of the traditional PCB. They can then discover each other and communicate by means of high speed serial wireless or optical communication. This is not to say that some limited wired connection on the frame to distribute specific signals and power may not be necessary – however the multitude of metal signal paths on modern PCBs would be redundant.
A review of these problems and trends indicates that the replacement of the custom designed PCB with a multi-purpose multi-product intelligent communications framework could substantially cut manufacturing costs and generate major society and consumer benefits and leads to the following proposals:
PROPOSALS FOR A NEW CONSTRUCTIONAL METHOD
INTERNATIONAL CONFERENCE ON CLEAN ELECTRONICS, Edinburgh, 9-11 Oct 1995, Conference Paper, 'A Novel Architecture to Facilitate Disassembly and Reuse of Electronic Components and Sub-Assemblies', Proced. 214-217, publ IEE & IEEE, co-author D.M. Holburn, D.S. Jordan, C.E. Hawkins (Cambridge University)