Removing a component can expose residue that was difficult to reach on an intact assembly. It can also change the sample through heat, tools or added chemicals. Plan that disassembly with the laboratory before comparing ionic results from intact and opened assemblies.
State why removal is proposed
Identify the hidden region and the question that an intact-board extraction cannot adequately answer. Preserve images and any nondestructive evidence before disassembly. Agree on a method that minimizes unrelated changes while respecting the sample’s value and the test requirements.
Zestron’s study description explicitly compares ionic extraction from intact assemblies with extraction after low-standoff components are removed. This highlights access as a measurement consideration; it does not make every removal method analytically equivalent.
Record what disassembly introduces
| Event | Possible comparison issue |
|---|---|
| Heating | Changed condition of residue or surrounding materials |
| Added flux or solvent | New material in the region being analyzed |
| Tool contact | Transfer or displacement at the sample location |
| New access | Previously shielded surfaces now included in extraction |
Use blanks and controls selected by the laboratory when they are needed to distinguish handling contributions. A routine rework procedure may be suitable for repair but unsuitable for preserving a chemical-analysis sample.
Compare like samples where possible
Define how intact and removed-component specimens are selected. Record their build, location and process history. If the same board is extracted twice, recognize that the first extraction has already altered what remains for the second.
For example, a higher result after removing a component can support the presence of previously inaccessible material, but it needs interpretation alongside any flux used during removal. The numerical increase alone cannot separate those contributions.
Keep the removed component with the sample where it may retain relevant residue. Material can be divided between the board and the component underside during separation.
Photograph the newly exposed board and component underside before collecting material. A residue can remain concentrated at one edge or transfer with the component, and that spatial evidence may be lost once the extraction combines material into a single liquid sample.
Describe the supported conclusion
State the assembly state, extraction boundary and disassembly method with each result. Explain whether the comparison addresses extraction access, a cleaning-process difference or a proposed failure mechanism.
Do not use a destructive analytical preparation as evidence that an ordinary production cleaning route can reach the same region. The opened specimen has a different physical geometry.
The localized extraction guide defines the sampled area, while FTIR reference selection supports a complementary investigation when identifying the organic material is also important.
Move from reading to a build-ready project
Use the fabrication and assembly checklists to prepare drawings, production files and test requirements.
Open the DFM checklist