Engineering plastics (EP) have physical properties enabling them to perform in applications unavailable to commodity plastics. EPs operate over a wide temperature range, under high stresses and in demanding environments. Different chemistries account for the different properties of EPs and properties can be further modified with additives. Available chemistries include polycarbonates, polyacetal, also known as acetal or polyoxymethylene (POM) and polyether-ether-ketone (PEEK). Common additives are glass-fibre and carbon-fibre.

POM has high mechanical strength and rigidity compared to commodity plastics such as acrylic, but PEEK is recognized as having the highest chemical resistance, wear resistance and heat resistance among all Engineering plastics. However, PEEK is also the most expensive of all engineering plastics. One advantage of EPs over other materials is their ability to be manufactured in complex shapes.  Another advantage, for semiconductor applications, is the ability to modify the material resistivity with the addition of fillers such as carbon powder and carbon fibre. This enables the creation of products that are static dissipative that meets the wear and temperature requirements of different applications.

Acrylic and polycarbonate plastics are very commonly used plastics, with near endless applications. Acrylic comes in different forms, the most relevant of which is often called acrylic glass as its transparency, flexural strength and UV tolerance make it a useful alternative to glass. Polycarbonate is stronger than acrylic, had higher hardness and can withstand higher temperatures.

Both acrylic and polycarbonate are easily processed. In terms of cost, acrylic is more economical than polycarbonate, with corresponding decrease in hardness and temperature resistance.

Static dissipative polycarbonate tools are available with the addition of an anti-static coating, which may not be suitable for high temperature, high wear applications. Static dissipative acrylic tools are also available, but again with the addition of an anti-static coating, thereby incurring the same disadvantages as static dissipative polycarbonate tools.

Acrylic and polycarbonate will be an appropriate choice for tools that require a high rate of light penetration with low rate of refraction.

POM (polyoxyethylene-methyl) polymers come in two types: copolymers and homopolymers. Homopolymers are polymers formed of only one monomer (a type of molecule), whereas copolymers have more than one monomer in their structure. POM homopolymers and copolymers largely share the same properties, with some slight differences. Homopolymers (like Delrin products) have slightly higher mechanical properties (such as hardness) than copolymers but are more difficult to process and have lower thermal stability.

In general, POM polymers have a continuous use temperature of about 100°C, however this varies depending on molecular structure and presence of additives. Copolymers have a higher continuous use temperature than homopolymers. Static dissipative POM copolymers are also available, such as Celcon® CF802, which has a deflection temperature of 100°C (compared with the Delrin 300ATB static dissipative POM which has a heat deflection temperature of 70°C).

POM is a widely used material in Die Attach and Wire Bond tools due to its ease of manufacturability and economical price. POM is used in a wide range of applications, from Pick Up Tips to Needle Holders and Pepper Pots.

Delrin 300ATB BK000

All Delrin grades are POM polymers. This particular grade is filled with an additive. This grade is not as hard as other POM grades, but it is unique among Delrin grades in that it has conductive properties, whereas all the others are insulative.

The deflection temperature of Delrin 300ATB BK000 is 70°C.Delrin Black has a deflection temperature of 121°C, and a stated maximum continuous operating temperature of 82C. Delrin 300ATB has a lower deflection temperature therefore an implied maximum service temperature lower than 82°C.

Delrin 300ATB and Delrin Black is suitable for all standard POM applications with the requirements of Static Dissipative performance.

PEEK (polyether-ether-ketone) is recognized as having the highest chemical resistance, wear resistance and heat resistance among all thermoplastics. Continuous service temperatures of PEEK grades range between about 239-260°C, with short-term excursions up to ~300°C. However, PEEK is also the most expensive of all engineering plastics. It is also much more difficult to process compared to, for example, POM plastics. Not only is the material more expensive, but the processing of it is also more expensive, and this overall cost needs to be considered when selecting material. Accordingly, PEEK is only used when other plastics are unsuitable for the application, or when metals cannot be protected from corrosion.

PEEK HT

PEEK HT (high temperature) is a PEEK grade designed for applications requiring resistance to higher temperatures than other plastics, as well better resistance to corrosion than metals. It has a slightly different chemistry to standard PEEK, resulting in slightly different properties. It has excellent wear and fatigue resistance and retains its mechanical properties at temperatures~30°C higher than standard PEEK grades. This means that for a given service temperature PEEK HT will have a much longer service life than standard PEEK.

PEEK GF 30%

PEEK GF 30 is filled with 30% glass fibre. The addition of glass fibre gives this grade increased rigidity compared to other PEEK grades. The service temperature, as well as hardness, remain comparable to other PEEK grades, however this grade is unique in that its high strength is maintained even at temperatures of ~150°C. This makes it ideal for high temperature structural applications, such as tools used in Ejection Systems.

PEEK CF 30%

PEEK CF 30 is filled with 30% carbon fibre. Its carbon fibre reinforcement gives the material a high level of rigidity and strength. Its stiffness and resistance to creep are even higher than glass fibre reinforced products. The addition of carbon fibre also enables the dissipation of charge through the material. This PEEK grade is the only grade, from the ones considered in this review, to have static dissipative properties. All other PEEK grades are insulators. PEEK CF30 is one of the optimum materials, out of all materials considered in this review, for hardness, service temperature and dissipation of charge.

In summary, PEEK is a very popular choice for Die Attach applications. From Pick Up Tools to Single and Multi Tip Ejector Needles, PEEK offers high performance at an acceptable price point with excellent Cost-Per-Part value.