The one thing to get right
Name the symptom, not just the product. A request that says "send a backup board sample" gets the volume-line grade, which is the right answer to a question you may not be asking. A request that says "burr on the exit side of a 12-layer stack at 0.20 mm" points at a specific grade and a specific surface, and that is the difference between an evaluation and a formality.
What a sample is here
A sample is a cut piece of the production board, taken from the same stock and the same production run that goes out on commercial orders. It is not a marketing swatch, not a hand-prepared lab panel, and not a different grade with the same name. That distinction is the whole point of sampling: a buyer needs to know what the delivered material does, and a sample that does not represent the production lot tells you nothing about that.
The consequence is that samples come in formats rather than in one universal size. Boards are produced in standard sheet formats and cut down; the same cut-to-size capability that serves orders serves samples. So the useful request states the format you can actually handle on your line — a sheet, a panel-sized piece, or a strip wide enough for the coupon positions your quality system uses.
One limit belongs here rather than in the small print. If the grade you want is not one we produce, the honest answer is that we will say so rather than send something adjacent and let the evaluation decide. Substituting a similar grade for a requested one destroys the value of the sample, and the grade boundaries on this site are drawn where they are for that reason — the HDF grades are 840, 880 and 950, and those three are not interchangeable in a stack that has been qualified on one of them.
What you can ask for
The list below is the sampling catalogue, grouped by what the layer does rather than by product name. Grades are given by the code used on the datasheet and on the acknowledgement, so a request can name one unambiguously.
| Layer | Family and grades | Sampled when… |
|---|---|---|
| Backup — volume lines | HDF 840 / HDF 880 / HDF 950 | The stack is single or double-sided and the priority is consistency per unit cost |
| Backup — humidity and HDI | UV melamine 840 / 880 / 950 | Flatness and dimensional stability are the constraint, or the climate is humid |
| Backup — high-reliability | Melamine laminate on HDF, white melamine, phenolic PHE | A substrate or high-layer-count build requires a specific surface or hardness |
| Backup — special cores | Kraft paper, phenolic PHE, coated wood 2.7 mm | The exit condition, or the thickness of the layer itself, is part of the specification |
| Entry — standard | AA1100 H18 aluminium entry sheet | Normal hole drilling where entry heat and bit guidance both matter |
| Entry — micro-hole and HDI | LE sheet and lubricant-coated aluminium | Small diameters, dense patterns, or a heat-driven symptom at the entry |
| Entry — back-drilled stacks | Back-drill aluminium | The stack is also back-drilled and the entry layer has to support controlled depth |
| Entry — positional accuracy | Phenolic entry board | The entry side is inside the accuracy budget rather than the heat budget |
Two grades of the same family are not a range to choose between at sampling stage. If you are evaluating 880 against 950, request both and run them in the same stack position on the same day — a comparison across two deliveries is not a comparison of two grades.
What to send with the request
Six inputs turn a sample request into a grade recommendation. None of them requires you to disclose your yield data or your customer, and the first four are the ones that decide the answer.
| Input | Why it decides the grade |
|---|---|
| Hole diameter range, smallest to largest | Sets whether the entry layer is inside the accuracy budget and how much heat concentrates at the entry |
| Panel or stack format and thickness | Determines the sheet format to cut and how long the bit stays in the stack |
| Board class and layer count | Separates a volume double-sided line from an HDI or substrate build |
| The symptom, if one exists | Burr, wall quality, positional error, breakage and warp each point at a different layer |
| Sheet format you can handle | Lets the sample arrive in a size you can run rather than one you have to re-cut |
| The date you want to evaluate by | Sets the cutting and dispatch schedule, and lets us tell you honestly whether the date is reachable |
If you have already isolated the symptom to a layer, say which one and how you isolated it. A request that says "we changed the bit and the parameter set and the problem stayed" is a much stronger starting point than one that lists the symptom alone, and it shortens the route to the right grade considerably.
How the request runs
Five steps, and the second one is where most requests either gain or lose their value.
- You send the inputs. Hole diameters, format, board class, symptom, handling format and evaluation date, through the request samples and quote form. If you have a datasheet requirement, name the document you need at this point rather than after the sample arrives.
- We confirm the grade, the format and the route in writing. The grade is stated by code, the format by its cut dimensions, and the dispatch window against your evaluation date. If the grade you asked for is not one we produce, or the format cannot be cut from standard stock, this is where you find out — before anything is cut.
- The sample is cut from production stock. Same stock and same run as commercial orders, cut to the agreed format, with the datasheet for that exact grade attached.
- It ships from our production base in Foshan. We do not operate an overseas warehouse and we do not appoint local distributors, so we will not present the sample as locally available. Where no local presence exists in your market, the sample travels directly from the mill and the route and timing come from the confirmation in step two — which is also why we ask for your evaluation date rather than quoting a generic number.
- You evaluate, and we answer the follow-up. Most evaluations raise a second question — a different gauge, a different format, a datasheet field your quality system needs. Send it against the same reference and it is handled as a continuation rather than as a new enquiry.
Where sampling sits inside a formal supplier qualification, the paperwork route matters as much as the material. The document families a qualification gate usually asks for, and the stage at which each becomes necessary, are set out under how samples fit the qualification process. Two of the situations behind our case studies stalled on documentation rather than on the material, which is why it is worth raising early.
What to check when it arrives
A sample that is not measured against the datasheet is an impression rather than a verification. Four checks turn it into one, and all four are done with equipment you already have.
- Thickness against the stated tolerance. Measure at several points rather than at the centre. The grade datasheet gives the nominal thickness and its tolerance, and the two together are what the stack height depends on — the nominal alone is not a specification.
- Flatness and warp at the state of use. Measure after the board has been in your own store or drill room rather than straight out of the packaging, because that is the condition it will be used in. The storage and seasoning reasoning is on the moisture control guide.
- Surface, on the side that matters. On a backup board the exit-side surface is what governs burr; on an entry board the surface the bit contacts first is what governs guidance. Check the working face, not the top of the stack.
- One isolated run. Hold the bit, the parameters, the panel lot and the stack position and change only the material. Then quantify it: the drilling defect rate calculator converts observed counts into a rate you can compare against your own baseline, which is the only comparison that means anything.
If the sample fails a check, send the measurement back rather than the conclusion. A thickness reading, a warp figure and the point in the run at which a symptom appeared are what let us either correct the grade choice or confirm that the grade is right and the constraint is elsewhere in the stack.
Questions buyers ask
Do you have local stock or an appointed distributor near my factory?
We will not imply a local position we cannot support. Our production base and our cutting are in Foshan, China, and samples are dispatched from there. Where we do not have a local presence in your market, the sample travels directly from the mill and the route and timing are stated with the quotation rather than presented as local availability. If local stock or an appointed local distributor is a requirement for your qualification, tell us on the request and we will state the actual position for your market instead of leaving it ambiguous.
What information should I send with a sample request?
The inputs that decide the grade are the hole diameter range, the panel or stack format, the board class and layer count, and the symptom you are trying to remove if you already have one. Add the sheet format you can handle, the surface you currently run, and the date you want to evaluate by. With those, the sample that arrives is the grade the stack points to rather than a default.
What size is a sample, and is it charged?
A sample is a cut piece of the production board from the grade under evaluation, taken from the same stock that ships on orders, not a marketing swatch or a lab-only preparation. It is cut to a size that lets you run a real evaluation on your own line. Commercial terms — whether the sample is free and who carries the freight — are stated on the quotation for the specific grade and format, so ask there rather than assuming either way.
How long does a sample take to arrive?
We do not publish a fixed lead time here, because a number that is not held is worse than no number. Cutting and dispatch are scheduled against the evaluation date you give us, and the window that applies to your format and route is confirmed in writing with the quotation. If your evaluation has a hard date, state it on the request and we will tell you whether it can be met before you commit to it.