What this section is for
A bare board is a fabrication problem. An assembly is a supply-chain problem with a fabrication problem attached.
Placement is the visible part and the least interesting part. The decisions that determine whether an assembly order goes well are made earlier: who buys the components, who holds the leftover stock, who carries the price movement between quotation and build, and what standard the finished work will be judged against.
This section is about those decisions. It is written for the engineer who has been handed the sourcing as well as the design, and for the buyer who has discovered that a PCBA quotation is not comparable to another PCBA quotation unless the two are describing the same model.
The organising idea
An assembly order transfers more risk than a fabrication order, and almost none of that risk is visible on a quotation.
A bare-board quote is close to complete: material, layers, finish, quantity, price. An assembly quote is a fragment of a longer document that also covers component sourcing, allocation, kitting, test coverage, acceptance criteria and what happens to the parts nobody used. Two quotes can differ by five percent and describe arrangements that differ by a great deal.
The pages here exist to make that longer document visible before it is signed.
Where to start
Turnkey or consignment
The first decision, and the one that moves the most risk. Turnkey versus consignment sets out the four risks the choice transfers — component price, excess inventory, counterfeit exposure and allocation — and the partial model most programmes settle on after their first shortage.
The component side
Assembly cost in 2026 is driven by parts availability more than by placement speed. The memory and MLCC allocation analysis covers what allocation clauses do to a PCBA price and how the mechanism reaches a unit cost.
What the inspection standard promises
A purchase order that names an acceptability standard buys a judgement, not a reliability level. The quality and standards section covers which standards belong on a bare board, which on a populated one, and why an order that names only one of them has specified half the product.
Where fabrication stops and assembly starts
Most avoidable assembly defects originate on the bare board: mask expansion, annular ring, copper-to-edge clearance. The lamination analysis covers the fabrication-end failures that only appear after reflow, and the DFM section covers the design decisions that cause them.
What an assembly quotation should contain
A quotation that gives one number for "PCBA" is not comparable to anything. Six items should be visible before the total makes sense: whether components are included and at what price basis, the validity of that component price, the acceptability class the work will be judged against, the test coverage included, the handling of excess material at end of build, and the terms that apply if a part is unavailable.
Where any of those is missing, the number is not wrong — it is undefined. Two suppliers can quote the same board, differ by five percent, and be describing arrangements that differ by a quarter of the total once the missing terms are resolved.
The test is simple. Ask what happens to the leftover material, then ask what happens if the twelve-week part slips a month. A supplier who answers both without hesitating has a model. One who answers neither has a price, and a price is not a plan.
What this section will not tell you
It will not tell you that any particular model is cheaper. The difference between turnkey and consignment on a given BOM is usually a few percent in one direction or the other, and it moves with the market; the risk difference does not move, and that is the part worth designing around.
It will also not tell you that an assembly can be qualified from a report. Placement accuracy, reflow profile and inspection coverage are process facts, and they are verified by looking at the line and the records, not by reading a certificate.
The useful question on an assembly order is not "what is your price" but "what happens when a part is short". The answer tells you more about the supplier than any capability list.
What we can and cannot do
We quote both sourcing models and we assemble to a stated acceptability class, with the class written into the purchase order rather than assumed.
What we cannot do is guarantee component availability beyond the allocation we hold, or certify that an assembly will meet a reliability target that depends on the design, the environment and the duty cycle. Those belong to the programme. What we can do is state the terms clearly enough that the risk lands where you intended it to land, which is the purpose of this whole section.