PCB | May 28, 2008

RFID on Printed Circuit Boards

The market for Radio Frequency Identification (RFID) is growing fast. Market experts predict sales will increase from US$ 1.2 bn in 2008 to US$ 3.5 bn by 2012. A reason for the increasing demand for RFID technology is the avid interest in managing and tracing products and services, in particular in safety-conscious sectors.
This is where alpha-board’s concept comes to the fore: The Berlin based company for electronics design and manufacturing now supplies PCBs with RFID technology.

PCB identification
PCBs are usually labelled with barcodes or 2D code labels in order to identify, e.g., product series during further manufacturing steps. Labels are a cost-effective solution – however, they require lots of space on the PCB. A scanner identifies the PCBs which are then assigned with the aid of a database.

Manufacturers profit from labelling their assembled PCBs with RFID technology:
• Space saving solution
• Improved assignment due to increased identification number
• Improved readability (e.g. for soiled, hard to reach positions, etc.)
• Additional storage space for assembled PCB-related information

Below a brief overview of various methods to identify assembled PCBs:
1. Barcode: An adhesive label is attached to the PCB. The barcode usually identifies an assembled PCB series. The barcode just consists of an identification number for which assembled PCB information is stored in a database.

2. 2D code (e.g. dot-matrix): This is a two dimensional code which in contrast to the barcode can also store assembled PCB-specific data. 2D codes have excellent error correction properties and can sometimes still be read even after being damaged, e.g. scratched or soiled. These labels are also attached to the PCB. Disadvantage: A special 2D scanner is required to read the matrix!

3. RFID label: An adhesive label with integrated RFID TAG is attached to the PCB the same as a barcode label. Non-destructive removal of these labels is not possible. RFID labels can be read via a scanner – also from greater distances – thus identifying the assembled PCB. Moreover, the labels store assembled PCB-specific additional information. The space-saving labels are extremely small (the size depends on the actual reading range) – i.e. they can be attached to very small PCBs or flex boards. In comparison to barcodes or 2D codes, RFID labels are more expensive, but they offer considerably more benefits.

4. TAG: A TAG is a complete RFID transponder with chip and antenna, and usually sealed in a housing. A complete TAG can be embedded in a PCB. The chip is mounted on the PCB and the conductors are used as the antenna. Both these processes require additional steps and depend on the structure and specifications of the PCB, e.g. thickness, flexibility or rigidness, etc. Since new calculations are always required for this version, it is comparatively expensive. Further cost factor: If the TAG is defective, the PCB can also be discarded!

However, it is beneficial that the RFID transponder is connected permanently to the PCB and cannot be removed. TAGs are placed the same as a PCB component or attached like an adhesive label.

Solutions from alpha-board
The RFID label is favoured by alpha-board. In a cost-benefit sense this version is less expensive and easier to realise. RFID labels can always be attached to a PCB if the PCB is large enough and the substrate is non-metallic. If a label cannot be attached to a PCB which is too small or due to the high packing density, alpha-board pursues a different strategy: A small TAG is mounted on the PCB just like a board component.

Traceability is an important feature for PCBs in safety-conscious sectors, e.g. the aerospace industry. For example, if certain components malfunction and all the coordinates of certain parts have to be traced, the RFID comes into its own: It is possible to read all the PCB data relatively quickly via the reader. This not only results in increased safety, it also saves time.

Even the initial costs for the utilization of RFID technology are favourable: The existing barcode technology can be effortlessly updated. And the more TAGs used, e.g., in an aeroplane, the lower the actual costs per unit are.

RFID in the aerospace industry
RFID chips on PCBs are, as yet, not a standard feature in the aerospace industry. However, all the signs are that traceability right down to the smallest screw will become obligatory. In the RFID field, "alpha-board offers something which everyone is currently looking for: We predict a high future demand for RFID labels on all PCBs in the aerospace industry," says Frank Külich, Technical Manager at alpha-board.

RFID on board also provides support for maintenance purposes. For example, as additional redundancy, the following assembled PCB information would be interesting for direct probing at the part:
• Manufacturer data
• Part number/Order number
• Current production number/Production date
• Configuration status
• If applicable, software release
• Malfunctioning history
• Repair history

This information can be provided by the assembled PCB directly via the chip or retrieved from a central database. For example, RFID could allow information to be read for an entire rack of circuit boards or individually (bulk reading) – a highly attractive option.


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