What to ask a PCB factory for: certificates, test reports and samples

A buyer placing an order with a new printed circuit board factory relies on documents: certificates, test reports and qualification results. Each record answers a narrower question than its title suggests, and together they decide what is known about a lot, a plant and a design. This note sets out what each common record shows, which certificates the Thai plants in the MPBxChange register publish, and how the evidence can be written into a request for quotation.

Key points

• Evidence for a printed circuit board order falls into three groups: records that come with each delivered lot, evidence of what the plant can make, and qualification tests agreed for the product.
• An electrical test of every finished board checks continuity and isolation against the design data.^[2] Plating thickness is read from a microsection^[3] and impedance from a TDR measurement.^[4]
• Of the 39 Thai fabricators in the MPBxChange register, 17 publish a certificate issued to the Thai plant itself, and 12 more publish only their parent group's certificates.^[22]
• A UL recognition holds within its listed limits, such as maximum operating temperature, flammability rating and soldering profile.^[13]
• In 2019 IPC warned that stacked microvias can fail after assembly in products that had already passed lot acceptance testing.^[20]

Three groups of evidence

A purchase order for bare boards usually names a drawing, a fabrication specification and a quality class. The records a buyer can request answer three different questions, and they arrive at different times.

The first group describes boards that already exist. The second describes a factory. The third describes how a construction behaves under stress, and it is the group most often left unstated in a request for quotation.

Records that come with each lot

Certificate of conformance

A certificate of conformance (also called a certificate of compliance) states that a lot meets the order and lists the measured results behind that statement. NCAB Group, a PCB supplier, issues one with measured data for every date code it ships, while a first article report covers only the first batch delivered.^[1] A useful certificate names the drawing and revision, the lot or date code, the quality class and the actual measured values, so that it can be checked against the order line by line.

Electrical test

Finished bare boards are tested for opens and shorts. A NASA Goddard workshop on board inspection describes boards undergoing 100% electrical test on simultaneous testers, to parameters set by the customer, with the test program built from the netlist or Gerber data.^[2] A bed of nails fixture tests faster than a flying probe but requires a complex fixture made for the design.^[21] The record worth asking for states the netlist revision, the share of nets tested and the continuity and isolation limits used.

Microsection report

A microsection is a polished cross-section through plated holes, cut from a test coupon on the production panel. It shows surface plating and hole-wall copper thickness, annular ring, drill registration and any separation between inner layers.^[3] Because the coupon is destroyed, a microsection report describes the sampled coupon; the agreed sampling plan says how many coupons stand for a lot.

Impedance test report

Controlled-impedance boards are checked by time domain reflectometry (TDR), which reads the characteristic impedance of a line and where it changes along its length.^[4] The measurement is normally made on impedance coupons built into the panel, and the report compares each measured value with the target and tolerance on the drawing.

Surface finish, solderability and cleanliness

Nickel and gold thickness on an ENIG finish is measured by X-ray fluorescence (XRF), and IPC-4552B sets the calibration the instrument must meet for the reading to count.^[6] Solderability is tested either by dipping a sample and inspecting the wetting or by simulating the surface-mount process, and test laboratories list J-STD-003 among the methods they apply.^[5] Ionic cleanliness can be reported as a single total by a ROSE test or broken down by ion with ion chromatography, which identifies the contaminant behind a high result.^[7]

Laminate and first article

The laminate certificate ties a lot to its material. A laminate maker's data sheet identifies the product by glass transition temperature (Tg), IPC-4101 slash sheet numbers and UL file number, which gives a buyer fixed reference points for the certificate of each lot.^[8] Dimensions, hole sizes and markings are recorded once in a first article report on the first batch delivered.^[1]

Evidence of plant capability

Quality management certificates

A management system certificate describes how a site is run. ISO 9001 sets a general framework for quality management, and its sixth edition, ISO 9001:2026, was published in September 2026; ISO 13485 is the version written for medical devices.^[9] IATF 16949:2016 is the quality management standard of the automotive industry, and the International Automotive Task Force offers an online check of whether a certificate is valid.^[10] AS9100, used in aviation, space and defence, was developed by the International Aerospace Quality Group on the basis of ISO 9001, and certified suppliers are listed in the group's OASIS database.^[11] ISO 14001 is the corresponding standard for environmental management systems.^[12]

A certificate covers the sites named on it. The MPBxChange register records a certificate against a plant only when a public source names that plant. As read on 15 October 2026, the certificates published for the Thai plants of the 39 fabricators in the register were:^[22]

Seventeen of the 39 publish at least one certificate for the Thai plant. Of the other 22, twelve publish certificates only for their parent group and ten publish none; six of the 22 are still under construction or announced.^[22] A certificate number, the certifying body and the address on the certificate are the three details that connect a document to the plant that will make the boards.

UL recognition

UL recognition of printed wiring boards under UL 796 applies to a listed board type within stated limits. In UL's own example, a board is recognized with a maximum operating temperature of 130 °C, a V-0 flammability rating and a tested soldering profile, and the listing can be looked up in UL Product iQ.^[13] Boards that go beyond the listed limits, for example a higher operating temperature or a different laminate, need further testing before the recognition covers them.^[13] The plant's UL file number is the key to that lookup.

Capability tables and equipment

A fabricator's capability table usually separates standard limits from advanced and development limits for each feature, such as layer count, trace and space, drill size and aspect ratio, and the values differ from one facility to another.^[14]

Process controls matter as much as the table. Inner-layer cores are inspected by automated optical inspection (AOI) before lamination,^[2] and X-ray systems in board plants are used mainly to check layer registration. X-ray inspection may miss some defects on finished boards, and microsections rely on small samples standing for a whole batch.^[15] A list of machines therefore says less than a description of how each inspection is applied: which layers, which lots, and what share of boards.

Qualification for the product

Performance classes

IPC-6012 groups rigid boards into three performance classes. Class 1 covers general electronic products, Class 2 dedicated service products where uninterrupted service is desired, and Class 3 products that must provide uninterrupted service even in harsh environments, with no downtime.^[16] The class sets the acceptance criteria applied to every lot, so it belongs on the drawing and in the request for quotation. Defence buyers commonly go further: L3Harris requires its board suppliers to have inspectors certified to IPC-A-600, the acceptability standard for printed boards, and to be able to verify compliance by microsection.^[17]

Tests on coupons

Reliability is shown by stressing coupons built with the same construction as the product. In NASA's work on microvia reliability, coupons were first heated several times at reflow temperature and then thermally cycled with interconnect stress testing (IST); phenolic-cured FR-4 coupons with microvias passed 1,000 IST cycles at 190 °C after five exposures at 230 °C, while lead-free reflow preconditioning degraded some constructions severely.^[18]

Conductive anodic filament (CAF) is copper growing along the glass and resin inside the laminate between conductors at different voltages, most often from hole to hole.^[19] It is tested by holding coupons at high temperature and humidity, such as 85 °C and 85% relative humidity, under voltage bias and watching for a drop in insulation resistance.^[19]

Microvias in HDI boards

High-density interconnect (HDI) boards connect layers with laser-drilled microvias, and stacked microvias are the construction most exposed to latent failure.^[20] In March 2019 IPC warned that microvias can fail latently after reflow, and that many of the failing products had already passed traditional production lot acceptance testing.^[20] For HDI designs, the reflow preconditioning and IST results on representative coupons are the evidence that speaks to this risk.^[18][20]

Putting the evidence into a request for quotation

A request for quotation can name the evidence in the same three groups, so that each plant prices the same scope:

The request form on MPBxChange lets a buyer list the certificates a plant must hold, and the plant pages in the register show the certificates published for each Thai site.^[22] Drawings and private requirements can be shared with a plant once a non-disclosure agreement is in effect.

Data and method

This article covers bare printed circuit boards; assembled boards are outside its scope. It draws on public pages of standards and certification bodies, NASA technical reports, laminate and test equipment makers, PCB manufacturers and trade press, each opened on 15 October 2026. IPC standards are named and described through these sources rather than quoted. Register figures were read from the MPBxChange plant register on 15 October 2026: a certificate is counted for a Thai plant only when a public source names that plant, and certificates published for a parent group are counted separately. The records described are those commonly requested; the purchase order and the agreed specification decide which apply to a given order.