Rigid-flex cost drivers: a procurement worksheet

A useful rigid-flex cost comparison starts with matched requirements and quantities. Separate one-time charges from recurring unit prices, identify what each quotation includes, and record every exception. The lowest printed unit price is not necessarily the lowest cost for the same deliverable.

The worksheet below uses invented numbers to demonstrate comparison arithmetic. It is not a quotation, market-price estimate, production promise, or evidence of our pricing. Its purpose is to help engineering and purchasing ask more precise questions.

Separate fixed and recurring charges

For a simple comparison, let F be one-time charges, U be the quoted unit price, and Q be the order quantity. If those are the only included charges, the quoted total is F + U × Q. Dividing by Q gives an effective cost per unit of U + F/Q. Keep excluded items in separate rows instead of assuming they are zero.

In this simplified example, B becomes less expensive when 600 + 18Q exceeds 1,000 + 15Q. Rearranging gives 3Q > 400, so B is lower from 134 whole units onward. This crossover is meaningful only if the offers cover the same requirements and their prices remain valid at that quantity.

Build a scope comparison before choosing

• Part number, revision, and required quantity.
• Approved region drawing and stackup.
• Surface-finish requirements and marked exceptions.
• Electrical test and inspection records included.
• Panel or individual-board delivery format.
• Packaging, freight, taxes, and any other excluded charges.
• Validity period and the conditions attached to each quoted price.
• Any proposed material, tolerance, or construction substitution.

A cost reduction tied to a changed construction is a design proposal, not merely a commercial discount. Give the engineering owner the proposed change and its affected requirements. Compare prices again only after deciding whether the revised scope is acceptable.

Ask about drivers without inventing percentages

Rather than assume that a particular feature adds a fixed percentage to cost, ask for a controlled comparison. For example, keep the same released design and request separate quotations at two quantities. Or ask the supplier to identify which unresolved requirement prevents a firm quotation. This separates a measurable commercial comparison from an unsupported rule of thumb.

For geometry alternatives, label each option with its own revision and explain what remains equivalent. Record whether the price difference includes changes to tooling, material, inspection, or other scope. A comparison is easier to interpret when only one approved variable changes at a time.

Make the technical baseline explicit

Before requesting competing quotations, identify the exact construction being compared. Include the part revision, rigid and flexible region map, stackup assumptions, finished dimensions, surface treatment, and agreed inspection requirements. If one supplier prices an approved construction while another prices an alternative, record them as different technical options rather than placing their unit prices in the same ranking without explanation.

Ucamco’s Gerber Job documentation identifies fabrication information such as finish, overall thickness, and materials as relevant to quoting and manufacturing planning. This supports a practical procurement rule: the price request needs construction information in addition to copper images. Confirm that the receiving supplier can interpret the supplied format and identify any information still missing.

Label preliminary assumptions clearly. If the stackup is not yet approved, ask whether the offer is budgetary or firm and what event triggers a price review. Do not compare a conditional estimate with a fully reviewed offer as though both carry the same technical certainty. Keep an assumptions column next to every amount that could change after engineering clarification.

Normalize what the quoted quantity means

Check whether the unit price applies to an individual board, a delivery panel, or another agreed unit. A panel containing several circuits is not numerically interchangeable with a single finished circuit. Record the quantity basis and the expected accepted deliverable. If the quotation uses a panel quantity, document the conversion before calculating a price per usable board.

For an illustrative arithmetic example, suppose an offer lists 50 delivery panels with four circuits per panel. The nominal circuit count is 200. If the price is 80 arbitrary currency units per panel, the arithmetic price is 20 per circuit before other charges. This calculation does not establish an allowance for missing or rejected circuits. The delivery acceptance agreement must define what is supplied and how any exceptions are handled.

Also distinguish order quantity from a forecast. A price based on a committed release may not apply to a nonbinding estimate of future demand. Ask the supplier which quantity and release conditions support the quotation. Record any minimum order, split-delivery assumption, or price-break condition in ordinary language so that the purchasing team does not infer terms that were never offered.

Expand the worksheet beyond the headline unit price

Use an explicit unknown marker for an unconfirmed charge. A blank cell or zero can make an incomplete offer look artificially attractive. If the decision must proceed before every amount is known, show the unresolved items separately and explain how they could affect the comparison. Avoid presenting a precise total that omits material portions of the scope.

Check quantity changes with a second calculation

Return to Offers A and B in the first table. At 100 units, A totals 2,400 and B totals 2,500, so A is lower by 100 arbitrary units. At 500 units, B is lower by 1,100. The reversal follows from the assumed fixed and recurring charges, not from a general rule that a particular supplier is cheaper at all production volumes.

If the project later orders 100 units followed by another 400, do not automatically substitute the single-order 500-unit total. Ask whether the second release has the same unit price, whether setup charges repeat, and whether the original quotation remains valid. The answer depends on the actual offer. A worksheet should represent those terms explicitly rather than making an undocumented assumption about how separate orders combine.

A useful sensitivity view recalculates the total at several quantities that the project might actually purchase. Keep the technical scope fixed while doing this. When a price break changes the unit price, use the applicable quoted value for that range rather than extending one price beyond its stated conditions. Save the calculation inputs so that another reviewer can reproduce the comparison.

Evaluate design alternatives as controlled options

Potential changes such as reducing layer count, changing an outline, or revising a surface-finish requirement need engineering review before they become procurement savings. Give each alternative its own identifier and state which product requirements remain satisfied. A less expensive construction that has not been checked against electrical, mechanical, and assembly needs is an unresolved proposal.

Ask for a comparison that isolates the intended change as much as practical. If a revised outline is quoted together with a different material and inspection scope, the price difference cannot be attributed to outline efficiency alone. Record all changes, including those that appear commercially minor, so that the design team understands what the lower price actually buys.

Include the work needed to accept an alternative in the internal decision. The supplier’s quoted fabrication amount may not include your engineering review, prototype evaluation, or documentation update. Do not invent a universal percentage for those activities. Identify them as project-specific tasks and obtain the relevant estimates from the people responsible.

Treat schedule statements as defined conditions

Ask what starts the quoted production interval: order acceptance, technical approval, material availability, or another explicitly agreed event. A number of days without a starting condition can be interpreted differently by purchasing and engineering. Record which open questions must be resolved before the supplier can commit to the schedule.

Separate production timing from transportation and receiving activities in the comparison. Do not describe a fabrication interval as a guaranteed arrival date unless that is what the offer actually promises. If an expedited option is proposed, identify the changed scope and price in writing and confirm that required inspections and documentation remain included.

Use an approval record that survives a repeat purchase

The final decision record should state which offer and revision were accepted, the normalized quantity basis, unresolved exclusions if any, and the approved technical exceptions. Include the calculation that supported the choice. This record allows a later purchaser to understand the decision without reconstructing a conversation or assuming that the previous lowest unit price still applies.

Before a repeat order, check whether the design, quantity, quotation validity, or delivery requirement has changed. Reopen only the relevant comparison items, but do not skip them because the supplier is familiar. A consistent worksheet makes the purchasing decision traceable while keeping engineering acceptance attached to the actual construction being ordered.

Keep the decision auditable

Save the compared offers, the normalized scope table, and the reasons for accepting any exception. If the project quantity changes later, recalculate the totals instead of reusing an earlier ranking. Keep uncertainty visible: an excluded charge awaiting clarification is an open item, not a free service.

Use our rigid-flex engineering tools and manufacturing overview to prepare the technical inputs. Request a project quotation through the inquiry form with the drawing, stackup, quantities, and required documentation. The more clearly these are defined, the more useful the comparison becomes.