Assembly Work Instructions and Operator Training

A work instruction tells the operator what to do at one station. It works when it is written for that station rather than for the product as a whole, and when it changes at the same moment the product does.

What Belongs on the Drawing

The drawing carries the specification: values, positions, polarity and the acceptance criteria that apply. The instruction carries the method: which tool, which setting, which sequence.

Duplicating the specification in the instruction creates a second source of truth. Our design release notes describe the release that should precede it.

What Belongs in the Instruction

The instruction should state the tool, the setting, the quantity of material, the sequence and the check that ends the step. Anything an experienced operator would have to remember belongs in it.

It should also state what to do when the step cannot be completed. Our floor control notes describe the escalation that goes with it.

Visual Aids and Boundary Samples

A photograph of a correct and an incorrect joint is worth more than a paragraph of text. Boundary samples, kept at the station, do the same job for a judgement call.

The samples have to be replaced when the criterion changes. Our joint criteria notes describe the criteria they represent.

Revision Control

The instruction carries the revision of the drawing it implements, and the station should not be working to an old revision after a change. The withdrawal of the old instruction is the part that most often fails.

The change record should state the effect on each station. Our fabrication notes list the points to confirm.

Training and Qualification

Training establishes that the operator can perform the step, and qualification records it. The record should state which revision the operator was trained to.

A new operator on a changed process needs both. Our floor notes describe the matrix that tracks it.

Auditing the Instruction in Use

The useful audit observes the operator without warning and compares what happens with what the instruction says. A discrepancy is a signal about the instruction at least as often as about the operator.

Our yield analysis notes describe how the findings are followed up.

Verification

The verification is an instruction that names its drawing revision, a station that carries the current revision only, a boundary sample kept at the station, and a training record that states the revision trained to.

Our quality notes describe how the records are kept.

Process Control and Verification

The process window is set by the narrowest step in the flow, so an improvement anywhere else shows up as margin rather than as yield until that step is addressed. A short note on the drawing about handling, storage or packaging is often worth more than an extra decimal place on a tolerance.

Where a value sits close to a process limit, the drawing should say so, since the shop can then open the process window rather than working to a nominal figure that carries no tolerance. A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used.

Where the requirement is not written down, the shop supplies its own default, and the default is chosen for the process rather than for the design. The measurements that matter are the repeatable ones: conductor width and spacing, annular ring, finished hole size, plating thickness and surface finish are all verifiable on a coupon that travels with the panel.

Running a first article through the same checks as the production panel confirms that the two agree, and that comparison is the cheapest form of process control available at prototype stage. Keeping a sample from the panel turns a dispute into a measurement, because the same coupon can be re-examined by both parties without rebuilding the batch.

Checks Before Release

The checks that matter are the ones performed on the product rather than on a sample kept for the purpose, because a coupon that travels with the panel is the only evidence about that panel. Where a requirement can be measured, it should be measured at the point of manufacture and recorded against the board or the lot it applies to.

A parameter that is set once and never re verified drifts, and the drift is usually discovered by a defect rather than by the record. The tooling, the material and the profile form one system, and a change to any of them should be assessed against the other two before it is released.

Where the process window is narrow, the measurement resolution has to be better than the window, or the data cannot distinguish a good part from a marginal one. A record that identifies the operator, the date and the settings is worth more than a record that identifies only the result.

The acceptance criteria should be written before the work starts, so that the decision is made by the specification rather than by the person inspecting.

FAQ

How long should an instruction be? Long enough to cover the step and short enough to be read at the station. If it runs to several pages it is usually covering more than one station.

Can the instruction be electronic? It can, provided the current revision is what the station sees and an old revision cannot be opened by accident.

What does gopcb provide for work instructions? We provide instructions written per station, a stated drawing revision on each, boundary samples kept at the station and replaced when the criterion changes, withdrawal of superseded revisions, and training records that name the revision trained to.