What a Helium Leak Test Certificate Should Include (And What Weak Reports Miss)

A leak test certificate is the audit trail for handover. It is what your operations team holds when the system is signed over, and what regulators or insurers will ask for if something goes wrong later.

A strong certificate is defensible. A weak one creates work months down the line. SEMI F1-96 specifies what should be ordered for leak testing services and what should appear on the certification. Here are eight items that should appear on any compliant report.

Item 1: Specification reference and date of issue

The certificate should cite the standard the test was performed against. For high-purity gas piping in semiconductor manufacturing, that is SEMI F1-96. The original document was published in 1990 and revised in 1995, with the current edition labelled SEMI F1-96.

Item 2: Acceptance test paragraphs applied

The certificate should name the specific test paragraphs from SEMI F1-96 that were applied. This is listed as an explicit ordering requirement in the standard.

Different test objects go through different sections. A component goes through Section 8.4. A subsystem goes through Section 8.5. A system goes through Section 8.6. Each has its own inboard, internal, and outboard subsections. The certificate should make clear which were performed.

Item 3: Qualification test paragraphs, where applicable

If qualification testing was performed in addition to acceptance testing, the relevant paragraphs should be referenced. Qualification tests are deeper and more closely controlled. They are used to establish the performance rating of a product rather than to verify a single unit.

Item 4: Design pressure used

Internal and outboard leakage tests are performed at the design pressure of the system, subsystem, or component being tested. The certificate should state the design pressure used. Without it, the test is not reproducible and the result is hard to defend.

Item 5: Leak rate limits and measured values, in the correct units

SEMI F1-96 expresses leak rate limits in kPa-L/sec and atm cm³/sec. The certificate should show both the limit and the actual measured leak rate for each test direction performed.

A common error to watch for: certificates that use “std cm³/sec” or “atm cc/sec” instead of “atm cm³/sec”. The standard uses atm cm³/sec. If a certificate uses a different unit, ask the provider to clarify what was measured.

Two conditional rules also need to appear on the certificate where they apply. When polymeric seals are present in the piping system, the internal and outboard leak rate limits are multiplied by 100. For new construction projects where measurement at standard limits is not practical, the outboard leakage limits are also multiplied by 100.

Item 6: Tracer gas specification

The tracer gas requirements in SEMI F1-96 are specific. For tests where the test object is enclosed in or sprayed with tracer gas, 100% helium is used. For pressurisation tests, 101.3 kPa (1 atm) of helium plus nitrogen to pressurise to design pressure. Helium purity must be less than 100 ppb total contaminants, filtered at point of use to less than 0.1 µm.

A certificate that does not record what was used is incomplete.

Item 7: Personnel and equipment used

SEMI F1-96 sets minimum qualifications for personnel: trained and experienced in mass spectrometer leak detector use, familiar with the ASTM test methods referenced by the standard, and familiar with the specific equipment used.

Equipment used in the test should be identified on the report, with calibration status. NIST-traceable calibration is the documentation standard. Helium mass spectrometer leak detectors commonly used by qualified providers include Inficon and Agilent. The certificate should only name the specific detector model that was actually used on that test.

What weak reports tend to miss

A short consolidation of items most often absent from underwhelming certificates: no specification cited, vague test method (just “leak test” with no direction specified), inconsistent units, no temperature record, no calibration date on equipment, no operator credentials.

Each of these maps to a specific requirement above. If you receive a report missing any of them, ask the provider for an updated version.

Need a SEMI F1-96 compliant leak test report?

Mechlink provides helium leak testing with full certification documentation. Singapore and Taiwan coverage, with less than 3 hour response subject to availability. Contact us to request a sample certificate format or to scope your project.