Making TGA Mass-Loss Reports Comparable for PCB Materials

A reported decomposition temperature is incomplete without its test definition. A material review should preserve the atmosphere, heating program, specimen form and endpoint used to obtain the number. Otherwise, an apparent improvement may compare different experiments rather than different materials.

Read the trace behind the headline

Request the original mass-versus-temperature trace and the stated analysis method. Identify whether the quoted temperature is an onset, a selected percentage of mass loss or another reported feature. Keep those labels attached when values are copied into a comparison table.

NETZSCH’s TGA application note shows that atmosphere and sample form influence decomposition results. Its comparison illustrates why measurements under air and inert gas cannot be treated as interchangeable material rankings.

Build a conditions matrix

Include coatings, copper or reinforcement retained in the specimen description. When a report refers to resin alone, do not silently place it beside a result from the complete composite. Ask the analyst whether an appropriate comparison can be made.

Investigate differences before assigning causes

Review any early mass change separately from the later event being used for decomposition comparison. The curve alone may not identify the substance responsible. If chemical identity matters, agree on complementary analysis rather than labeling every initial loss as moisture.

For an incoming-material dispute, retain material from both lots and arrange an agreed common procedure. This is more informative than exchanging isolated catalog figures with different footnotes. Keep the original reports available so the reason for the follow-up remains clear.

Where one specimen is finely divided and another is a solid piece, ask whether the preparation difference could affect the intended comparison. Document any preparation change in the revised test instruction rather than allowing it to become an unrecorded laboratory convenience.

Limit the resulting design claim

A TGA result characterizes mass change during its specified experiment. It does not by itself authorize a board assembly temperature, a continuous service temperature or a cure schedule. Those decisions need requirements and evidence appropriate to their actual exposure and failure mechanisms.

Release a comparison that names the matching conditions and unresolved differences. If the datasets cannot be aligned, present them separately and identify the additional measurement needed.

The DSC first-heat guide helps distinguish a cure investigation from a mass-loss investigation, while sample-preservation planning keeps destructive tests connected to the original board location.