WORKING THROUGH AND AROUND PVDF SHORTAGES

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Contributed by David Stiles, National Business Development Manager for Microelectronics

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As we are all too aware, demand for PVDF resin has climbed to an unprecedented level. In part, this is the result of a large number of new semiconductor fabs being built worldwide and the increased use in the production of lithium-ion batteries. Despite aggressive capacity expansion efforts by resin suppliers, demand continues to outstrip supply, and there appears to be no relief for the foreseeable future.
 
In the meantime, we need to support our customers as best we can. This situation presents a particularly difficult challenge to engineers responsible for specifying suitable piping for high purity water distribution systems in the semiconductor and life science industries. If PVDF availability is going to cause an unacceptable delay in a project schedule, alternatives may be discussed. Depending on the end-user application, natural and pigmented polypropylene, as well as Halar® (ECTFE), are all candidate materials that may be suitable as an alternative to PVDF.
 
In the case of water for the life science industry, several alternatives to PVDF already have a proven track record. Specifically, PolyPure® natural PP piping system has been used for ASTM Type I, II, and Type III water for many years. With the exception of instances where the media exceeds 80° C (e.g., water for injection) or clean-in-place systems that use incompatible cleaning agents, PolyPure® meets all requirements.
 
PVDF alternatives in the microelectronics industry are a much more challenging proposition. For the most part, the industry has gravitated to PVDF for ultrapure water (UPW) distribution systems. However, there are some instances where PP-Pure® pigmented PP piping system or Ultra Proline Halar® (ECTFE) may be suitable substitutes. 

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The following are a few applications for consideration: 
 

• Hot Ultra Pure Water (HUPW) Loops: The lifetime of PP-Pure® pigmented PP will be shorter than PVDF and will also require additional expansion loops and pipe supports. Halar® has excellent temperature resistance, but it has traditionally been used for chemical distribution rather than UPW. As a result, zero dead-leg valves are not available, and the maximum size is only 4”.  

 

• UPW Return Lines: Generally, these do not have the same purity requirements as the supply side. Therefore, it may be acceptable to use PP-Pure® for the returns, provided that it is understood that there will be an increased burden on the polishing system. 

 

• UPW Supply Lines: The water purity requirements of modern fabs are extremely demanding. They have been a driving force behind the adoption of PVDF. However, water quality requirements in older legacy fabs or ones producing relatively large device geometries are less stringent. It may be acceptable to use PP-Pure® even on the supply side of a distribution system. 

 
For all the applications listed above, pipe leach-out performance is a key consideration and plays a critical role in determining fab yield. We need to be cautious about substituting materials that could have a negative impact on the overall process. A lot of attention has been given to SEMI F57 leach-out results. Both Halar® and PP-Pure® comply with F57 standards. However, we need to be aware that fabs may take several months to rinse down a distribution system. SEMI F57, on the other hand, is only a one-week test. It is somewhat dangerous to use this test to extrapolate long-term leach-out performance. 
 
As long as PVDF is in short supply, those making specification decisions will need to weigh the tradeoffs with the benefits. Asahi/America will continue encouraging these discussions and help our customers find a solution.