Temperature Humidity Bias Testing: Review a JESD22-A101 Chamber Proposal

Begin with the test the laboratory will run

“85/85 THB” tells a supplier where the discussion starts, but not what will occupy the chamber or how the devices will be biased. The laboratory's plan should name the adopted JESD22-A101 revision, temperature and relative humidity, exposure schedule, DUT count, fixture layout, electrical requirements and acceptance criteria. That plan gives both sides a specific test against which to review the proposal.

If the test method has not yet been selected, start with the THB and HAST comparison. The review below assumes THB is already specified.

Read the standard ranges as a starting point

The SANWOOD standard-temperature humidity test chamber excerpt supplied for this review lists four temperature options. It helps screen a proposal, but does not identify the unit being quoted:

 The excerpt also lists 10.0%–98.0% RH, with its 10% RH lower endpoint specified at 60°C and above. It does not show a complete temperature–humidity operating map. In particular, the endpoints do not establish the laboratory's required combined condition with its fixture and powered DUTs installed.

The quotation should identify the offered option and include its applicable parameter sheet. A single-compartment unit and a two-level unit should be reviewed as distinct configurations; for the latter, check what is specified for each compartment. Any proposed loaded-condition assessment should address the actual arrangement in the laboratory's plan.

Trace the fixture and electrical path

The fixture, rather than the DUT alone, often sets the space requirement. Share its drawing or installed dimensions, board or socket layout, supports and cable route. The same review should include known heat dissipation from powered DUTs and any spacing or material constraint in the test plan. Empty-chamber dimensions cannot settle the loaded layout.

Then trace the bias path from the source to the DUT. State the needed channel count and device-specific voltage and current requirements. The proposal should say who supplies the source, chamber access or feedthrough, internal cables, fixture connections and measurement equipment. If an interface is offered, its drawing and itemized scope matter more than a general reference to a cable opening.

Agree on the evidence before ordering

A chamber controller and external bias equipment may keep separate logs. The qualification team needs to know which system will record the environment, which will record bias and DUT measurements, and how those records will be tied to the same exposure. A shared data system should appear in the offer if the project requires one.

Five points are worth settling in the quotation:

 Mark each item as included in the offer, supplied by the laboratory or still open. An open item should stay visible in the quotation; the standard parameter excerpt cannot settle the scope of the bias supply, feedthrough, fixture or data system.

Frequently asked questions

Can an existing THB fixture be reused?

Possibly. Its installed dimensions, cable route and electrical connections need to fit the proposed chamber. Previous use in another setup does not establish that compatibility.

Does the chamber quotation include the bias supply?

The published temperature and humidity ranges do not answer this. The quotation should name the bias equipment supplied by each party and any chamber interface or internal connection included in the offer.

Can both levels of a two-level chamber be used for THB?

That depends on the proposed configuration. Review the environmental condition, fixture space, electrical path and records for each intended compartment. The two-level form alone does not establish simultaneous test capability or an included bias system.

Request a proposal for the actual setup

For an RFQ, send the adopted test plan, required temperature–humidity condition, fixture drawing, DUT count, bias requirements, known powered heat load and the equipment already available in the laboratory. Include the records the qualification team expects to review.

Use the SANWOOD temperature humidity test chamber range to begin the discussion. The written proposal should identify the offered configuration, the supply boundary and the documents available to assess that specific setup.