Avoid the passive obsolescence trap by David Pearson Technical Director Anglia Components

The current sweet spot

Globally the largest percentage, by volume, of the chip passive market use 0201 size and below so it is no surprise that there is a long term trend for manufacturers to discontinue, or make fewer batches of, the larger sizes of chip passives: 1206, 0805 and 0603. We are already witnessing a managed obsolescence program on some of these larger chip sizes where capacity has been severely restricted.

The fact that the larger sizes consume more material and production capacity creates an active disincentive for manufacturers to produce them. In the past component manufacturers have responded to increases in demand and output using existing facilities and equipment. For example, the reduction in size from one platform to the next historically more than doubled the production yields for the equivalent amount of raw material. Although currently there isn’t a general shortage globally, each time the supply chain tightens we will always see greater pressure on the larger sizes than the smaller. Recently capacity availability has improved across the board however manufacturers are still not recommending these larger sizes for long term designs.

How should component users respond?

Currently 0402 and 0201 are the sizes that Anglia recommends for new designs. Larger sizes are still available, but the information we are being given by manufacturers is that they will become increasingly scarce longer term. You could end up being caught in an endless cycle of lengthening lead times, restricted capacity and rising prices. You should consider moving to smaller sizes such as 0402 and 0201 for current and new designs if they are compatible with your voltage and value requirements. If you have a design that you intend to continue producing for some time that includes larger chip passives it is worth considering a redesign just to get rid of them. Redesigns are expensive, but line stops even more so – and eventually you may simply be forced to redesign your board with smaller chip passives.

Most sub-contractors are now fully set up to place 0201 and even 01005 devices, and assembly of the smallest sizes doesn’t really present an issue. However, reworking boards with 0201 and 01005 chip passives can be challenging, therefore it is important for customers to fully understand any potential yield issues due to scrappage when moving to these smaller sizes before selecting which chip size to downsize to.

Are there alternative technologies?

Not every voltage and every value is available in the smaller chip sizes, sometimes this is simply because of the physical constraints of the material, and this is why our advice to customers is to move to the smallest chip size available in the value and voltage required. However, on high cap MLCC (values above 1uF) one alternative may be to use polymer capacitors. Whilst they are larger and more expensive on a same value and voltage comparison, they do not suffer with the same DC bias characteristic that MLCC capacitors do where capacitance decreases as voltage is applied, this means it is possible to use a lower capacitance polymer capacitor in the circuit design thus giving an overall system cost saving. This is especially true where multiple MLCC’s are being used to achieve a high capacitance value. However, polymer capacitors are polarised so they are not an option in circuits that may see a reverse bias or in AC applications.

Conclusion

We’ve had feedback that not all of our competitors are sharing this analysis with their customers. The reality is the largest manufacturers follow the demand of their key customers in the consumer segment and this defines which chip sizes they allocate capacity to, the demand for the larger chip sizes is simply not big enough in comparison to influence the market. If you include any device in your design that isn’t standard and widely available you’re taking a risk. If there are alternatives that can be substituted with comparatively little pain it is an unnecessary risk. As manufacturers discontinue or reduce production capacity on larger size chip passives, component users need to look at their options to ensure they don’t get caught out with inventory shortages, price increases and unworkable lead times.