Engineering resources
Bare-board requirements before assembly quoting
Before an assembly quotation is accepted, identify who supplies the bare boards, which receiving evidence is included, and who owns any conditioning or additional inspection. Otherwise the quoted assembly scope may exclude preparation that the selected polyimide construction needs.
A polyimide PCB should enter assembly with a documented construction and handling history. The objective is to identify the limits and instructions that apply to that board, rather than rely on a generic statement that polyimide tolerates heat.
Identify the complete assembly before choosing handling steps
Record the laminate and bonding system, surface finish, board thickness, components and any attached features. Check the current instructions for each relevant material and finish. Arlon publishes assembly recommendations specifically for 85NT; the existence of a grade-specific note is a reason to check applicability, not to copy its settings onto every polyimide construction.
Document packaging condition, storage duration and exposure after unpacking. If conditioning is required, obtain a procedure suitable for the actual board and finish. A material recommendation and an assembled-product process may have different constraints.
A receiving-to-reflow handoff
| Stage | Record | Open question that stops release |
|---|---|---|
| Receiving | Lot identity, package condition and required evidence | Does this lot match the approved construction? |
| Storage | Storage conditions and exposure history | Is the handling record sufficient? |
| Preparation | Applicable conditioning procedure and completion record | Is it compatible with this finish and assembly? |
| Thermal processing | Approved profile and actual process evidence | Are all relevant component and board constraints met? |
| Rework | Additional exposures and authorization | Does the proposed repair exceed the agreed process envelope? |
Example: counting thermal exposures correctly
Hypothetical recordkeeping example. A board is planned for two reflow passes and later receives one approved localized rework operation. Recording only “two reflows” omits a relevant event. The exposure record should distinguish the two whole-board passes from the local repair, including which location was affected and the process evidence available.
This does not mean the three events are thermally equivalent, nor that a particular count is automatically acceptable. Their conditions and the applicable qualification determine significance. The lesson is to preserve the history so engineering can evaluate it.
Close the quotation scope
List the board quantity, panel format, finish, handling requirements and required lot records in the RFQ. Ask the assembler to identify any assumed incoming condition and any excluded testing, conditioning or rework. Keep these commercial boundaries tied to the approved technical process rather than treating them as interchangeable line items.
Make exceptions visible
If the packaging is damaged or exposure history is missing, record the uncertainty and obtain a disposition. Do not relabel the board as properly conditioned without evidence. Equally, do not apply an arbitrary prolonged bake as a universal repair for missing records. Resolve the actual construction and handling requirements first.
The polyimide material directory identifies grades for review. Bring the specific construction and assembly plan into the manufacturing handoff, including intended rework and acceptance requirements. The outcome should be an agreed process envelope, not a generic temperature claim.
Discuss your fabrication package
Submit project requirements and fabrication files for review. Material suitability, availability and commercial terms require project-specific confirmation.
Sources and scope
Manufacturer references checked 9 October 2026. Examples and review worksheets are original editorial guidance, not approved process instructions. Historical reference documents are used for fundamentals, not current product availability.