Design Guide for PET Face Seal Blister Packaging in electronics and electrical: Draft, Radii and Draw Ratio

Thermoforming rewards designs that respect how a heated sheet stretches. These rules prevent most tooling rework and most thickness complaints.

This guide is written for engineers, purchasers and project managers who need a practical answer, not a resin data sheet.

Product Overview

This category covers a family of products rather than a single item. In practice a buyer defines face seal blister packaging by three things: the base resin, the format or dimension, and the performance or certification level it has to meet. Typical options in this category include single and multi cavity layouts; transparent, frosted and coloured; sheet gauge 0.20 to 0.60 mm. Materials most often specified are Polystyrene, Polypropylene, Polyethylene Terephthalate, Recycled PET, and the choice between them changes stiffness, temperature resistance, chemical behaviour and price.

In the electronics and electrical sector the decision is usually driven by ESD protection and dimensional accuracy, with cleanliness as a secondary requirement. Typical end uses include component trays, battery packs, device inserts.

Key Material Properties

These figures are typical for commercial grades and should be confirmed against the supplier's certificate for your specific lot.

Polyethylene Terephthalate is frequently the default selection here: High IV PET resin is the reason a 1.5 L bottle can be light yet hold carbonation pressure.

Design Rules for Thermoformed Parts

Thermoforming rewards designs that respect how the sheet stretches. These rules prevent most tooling rework.

• Use a draft angle of at least 3 degrees per side so the part releases without vacuum locks.
• Confirm the trim method early: steel rule die, CNC router or press tool each have different tolerances.
• Make corner radii at least equal to the sheet thickness; sharp corners are where holes start.
• Keep the draw ratio moderate: deep cavities thin the sheet and force you to start with a thicker gauge.
• Add ribs, steps or kiss-offs instead of increasing overall gauge to gain stiffness.
• Leave a flat sealing flange of at least 6 mm when the pack has to be heat sealed or lidded.

Send these rules to your designer together with the sheet gauge and the target cycle time; most tooling modifications come from ignoring draft and corner radii.

Common Grades and Variants

• Recycled PET based: lower carbon footprint than virgin resin
• Polypropylene based: lowest density among commodity plastics
• Polystyrene based: rigid and glossy
• Polyvinyl Chloride based: inherently flame retardant

Beyond the base resin, most suppliers offer UV stabilised, food contact, flame retardant, anti-static and recycled content versions of the same product. Ask which additive package is included, because it is often the difference between a part that lasts three years and one that lasts ten.

Processing and Finishing Options

Processing method drives both cost and performance, so it should be fixed early in the design.

• Vacuum forming
• Pressure forming
• Heat sealing
• Sheet extrusion

Secondary operations such as printing, welding, machining and assembly are often cheaper to do in the same factory, and they reduce the risk of mismatch between components.

How to Specify Face seal blister packaging Correctly

Use this checklist when comparing two or three supplier quotations.

1. leave a flat flange for heat sealing
2. check the corner radius against the sheet gauge
3. confirm the sealing coating matches the card
4. verify recycled content documentation if rPET is used
5. ask for a drop test on the finished pack

Send this list to your supplier with the drawing and you will receive comparable quotations from every factory you contact.

Frequently Asked Questions

What packing and shipping options are available?

Standard packing is export cartons on fumigation-free pallets, with custom labelling, barcode and retail packing available. We also handle consolidated containers and door to door delivery.

How do you control colour consistency?

Colour is controlled with a masterbatch reference approved by the customer, and every production lot is checked against the approved sample under standard lighting before shipment.

Do you offer samples?

Yes. Standard samples are normally free of charge and shipped within three working days; custom samples are charged at cost and credited against the first production order.

Which certifications can you provide?

We can provide ISO 9001 quality system documentation, material certificates, RoHS and REACH statements, and where applicable food contact, flame retardancy or drinking water approvals. Tell us your target market and we will match the document set.

What is the minimum order quantity for face seal blister packaging?

For standard sizes and colours the minimum is usually one pallet or one production run; for custom tooling the economic minimum depends on the tooling cost amortised over the expected volume. Send us your annual volume and we will calculate the break even point.

Conclusion

If you are planning a new electronics and electrical project, send us your drawing, annual volume and target properties, and we will come back with a material proposal, a tooling plan and a budget quotation.