The short answer
What this setting controls
A castellated module behaves like a large surface-mount component. Each half-hole becomes both an electrical terminal and a solderable edge feature.
Control drill diameter, annular ring, pitch, plating, edge location and host-board toe/heel allowance. Add mechanical support when solder joints should not carry insertion or cable loads.
Options in the order form
How the available choices differ
| Choice | Use it for | Engineering note |
|---|---|---|
| Recommended / default | Builds without a documented exception | Keeps the current compatible process path. |
| Alternative selection | A released drawing, stack-up or assembly plan requires it | Recheck every dependent option after changing castellated holes. |
Compatibility
What can change with this selection
- Very small holes or thin annular rings can tear during routing.
- OSP and some specialised finish/process combinations may be unavailable.
- If the page disables a choice, treat it as a compatibility result and adjust the controlling design decision rather than forcing the value.
Practical recommendation
How to make the decision
- Use castellations for solder-down modules and daughterboards.
- Keep copper and mask geometry symmetrical around the routed edge.
- Prototype the host-board footprint before production.
Before release
Check these points before adding the quote to cart
- Confirm the selected value matches the released Gerber, drawing, stack-up, BOM or assembly plan.
- Review any fields that changed automatically after this selection.
- Check the board preview and server-calculated estimate before adding the quote to cart.
- Use castellations for solder-down modules and daughterboards.
- Keep copper and mask geometry symmetrical around the routed edge.
- Prototype the host-board footprint before production.
Frequently asked questions
Answers for ordering and design review
What should I do if I am unsure about Castellated holes?
Keep the safe compatible default and add a concise question in Special instructions, or ask the TekRabbits concierge for guidance.
When should I change Castellated holes?
Change it when the released electrical, mechanical, thermal, assembly or quality plan gives a measurable reason. Otherwise keep the compatible default and review the resulting board preview and estimate.
Why is an option disabled?
The current material, geometry, layer count, quantity or another selected process makes that combination unavailable. Change the controlling selection or revise the design package rather than trying to bypass the disabled state.
Can I rely on the online choice as final manufacturing approval?
No. The interface screens known combinations and requests pricing, while final manufacturability remains subject to the released files and technical review.
What should I record outside the order form?
Put controlled requirements in the fabrication drawing, assembly drawing, stack-up, BOM or acceptance plan. Use Special instructions only for a concise pointer to that controlled requirement.
Will changing this update other selections?
It can. The order form re-evaluates compatibility and may replace a now-invalid dependent choice before requesting a fresh server-side estimate. Review every highlighted or automatically changed field.
What if the design requires an option that is not offered?
Do not approximate it with a different label. Recheck the controlling material and geometry, document the actual requirement, and request technical review before placing the order.
Useful engineering tools
Calculators and preparation guides
Further reading
Standards and technical references
Use the latest applicable revision and your organisation’s controlled requirements when a standard forms part of product acceptance.