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Finding the perfect size – considerations when choosing the size of your timing device

Posted: 25th March 2021

Finding the perfect size – considerations when choosing the size of your timing deviceAs most manufacturers of electronic devices continue to reduce the size of their products, pressure is put on to passive component manufacturers to continuously reduce the package sizes of their parts. But does reducing the package size of components only come with benefits, or are there some drawbacks to this trend as well? This blog provides an insight into the benefits as well as challenges that engineers face when using smaller components.

First of all, if a customer is looking to downsize their PCB or to create more space on an existing board for additional circuitry, smaller packaged components can help them meet this goal. This will help reduce the size of the end product or allow for more functionality to be included within the product.

However, smaller components can be more expensive in comparison to larger ones, and this applies to timing devices as well. The smaller parts are more complicated to produce and factories may have to acquire new production equipment or use new technology. Until the return of investment (ROI) those parts will be more expensive compared to others. In addition, the price of crystals in miniature packages such as 2.0 x 1.6 mm will slightly increase as it is harder and more expensive to develop new frequencies or new stabilities. However, at the same time larger packaged parts such as 7.0 x 5.0 mm can be more expensive because the volume in production dropped compared to other package sizes. This reduced quantity means that economies of scale can no longer be achieved in the manufacturing of these products.

Generally speaking, with increasing quantities the costs get reduced. This is due to larger order quantities for raw material (e.g. crystal blanks) and factories being able to use the same setting on the production machinery for more parts. This will save time, make it easier and cheaper to produce larger quantities of the same part. Because the smaller parts have not been around in the market for a long time, many projects are still in the design phase, however as soon as mass production starts the pricing for those components will decrease. With all this in mind the ‘sweet spot’ lies currently at 2.5 x 2.0 mm and 3.2 x 2.5 mm as these are the sizes which are more cost-effective.

Also, it is basically impossible to manually solder smaller parts onto a circuit board. Packages as small as 1.2 x 1.0 mm are difficult to accurately place on a PCB and the assembly of those parts will need the appropriate machinery. Pick and place machines need to be far more accurate when dealing with smaller parts and failure to place components accurately can lead to failure of the PCB assembly resulting in expensive reworking.

Generally, using fewer materials is better for the environment. For smaller components less raw material is needed and the packaging material can be reduced. Moreover, smaller parts are lighter and do not take up a lot of space during transport or in the warehouse and this can lead to a reduction in freight costs as well as costs for storage.

From a technical perspective, it is also important to consider that replacing larger crystals with  smaller parts affect their specifications. For example the generally higher ESR and the lower drive level could lead to a non-functioning circuit. For more information please read our blog: Does size really matter? – Design effect of crystal downsizing.

It is also worth considering that when using smaller packaged crystals these will generally be thinner in height. For crystals the frequency depends on the thickness of the blank, i.e the thicker the blank the lower the frequency will be. For that reason, it is not physically possible to offer frequencies below 16 MHz in the 2.0 x 1.6 mm package or below 24 MHz in a 1.6 x 1.2 mm package and this needs to be taken into account when switching from a larger to a smaller size. This only applies to crystals, for oscillators lower frequencies are also available in smaller sizes.

IQD offers a broad range of small parts throughout its crystal, oscillator, VCXO, TCXO portfolio. Moreover, we continue to offer our range of larger product packages. IQD also offers a range of engineering support services to guide customers from design stage through to full production.

For support in choosing the right product for your PCB please contact our Sales and Applications Support team.