Cross-sections do not have a single standard. It is located at the intersection of three different groups of documents: the group specifying test methods, the group specifying technical requirements of the board, and the group specifying solder joint acceptance criteria. Misquoting groups is the most common error in cross-sectional reporting.
This article classifies standards according to the subject of assessment, points out which ones regulate what, how to properly cite them in reports, and four common mistakes.
1. Why are there so many standards at the same time?
In an assembled circuit board there are at least three different objects, and each object has its own set of standards:
- Bare board: is the responsibility of the board manufacturer.
- Welding and assembly process: is the responsibility of the assembly plant.
- Test method: specifies how to cut, grind, polish, and measure — not specify an acceptance threshold.
Therefore, a standard sectional report often must reference simultaneously: a standard on test methods, a standard on technical requirements, and a standard on acceptance criteria.
2. Commonly used standard classification table
| Standard | Object | Regulate what? | Properties |
|---|---|---|---|
| IPC-TM-650 Method 2.1.1 | Test method | Process for preparing cross-sectional samples for printed circuit boards | Technical instructions |
| IPC-A-600 | Bare circuit board | Observable acceptance criteria, including on cross-section | Acceptance criteria |
| IPC-6012 | Hard circuit board | Feature and technical requirements: plating thickness, annular ring, plating continuity | Technical requirements |
| IPC-6013 | Soft circuit board | Technical requirements for soft and soft–hard circuit boards | Technical requirements |
| IPC-6016 | HDI board | Requirements for high density boards with microvia | Technical requirements |
| J-STD-001 | Assembly process | Requires materials and solder jointing process | Process requirements |
| IPC-A-610 | Assembled circuit board | Weld acceptance criteria for each product layer | Acceptance criteria |
| IPC-7095 | BGA | Design, assembly and void evaluation for BGA | Specialized instructions |
Points to remember: IPC-TM-650 2.1.1 prescribes how to do this, also IPC-A-600, IPC-6012 and IPC-A-610 define what constitutes. Mixing these two groups is a common reason why reports are questioned.
3. Three different types of thresholds need to be distinguished
| Threshold type | Who placed it? | Content example | When will it change? |
|---|---|---|---|
| Design threshold | Customer or designer | Desired plating thickness, hole diameter, number of layers | According to each project |
| Standard threshold | Industry standards | Minimum conditions for the product to be considered satisfactory | According to the standard version |
| Internal threshold | Factory | Tighter control level than standard to create a safe zone | According to process data |
Practical approach: take the standard threshold as the minimum level, set the internal threshold a range tighter in accordance with the procedure capacity, and clearly state in the records both thresholds.
4. Product class in IPC-A-610 and impact criteria
IPC-A-610 divides products into classes according to the level of reliability requirements, from general consumer goods to products requiring consistently high reliability. Cross-sectional acceptance criteria are therefore not the same between classes: some features are acceptable in low classes but not in high classes.
Practical consequences: must clearly state which class the product belongs to before debating pass or fail. The same cross-sectional image, two different layers can give two different conclusions — and both are correct.
5. How to cite standards in reports
A sufficiently strong citation requires four components:
- Standard number and name in full form.
- Version and year of issue — this is the most overlooked part.
- Specific section, section, or table applied for evaluation.
- Product class for class standards.
For projects with specific customer requirements, the order of priority should be added: customer requirements first, industry standards second, or vice versa – depending on the agreement in the contract.
6. Four mistakes when citing standards
| Mistake | Consequences | How to avoid |
|---|---|---|
| Use test method standards to conclude pass/fail | The report has no basis in criteria | Clearly separate the “how to” group and the “criteria” group |
| Standard version not recorded | Cannot reproduce conclusions, easy to dispute | Enter the model number and year of issuance |
| Apply the bare board criteria to the assembled board | Conclusion on the wrong subject | Clearly define the object before choosing standards |
| Skip the product layer | Endless debate because both sides use two different levels | Finalize the product layer right from the beginning of the project |
7. Frequently asked questions
Is it mandatory to follow IPC?
Not legally required, but in practice this is a set of standards recognized by the market. If the customer has its own standards, that standard usually takes precedence.
What if the customer does not state the product class?
Ask again in writing. This method not only avoids disputes later, but also forces the customer to confirm the actual request level.
What standards apply to connectors and cables?
This group belongs to standards on connectors and electrical connections, not part of the printed circuit board standards. It is necessary to choose the correct group of standards according to the subject.
Does the report need to include sampling standards?
Should state. Acceptance criteria are only meaningful when accompanied by the sampling method and the number of samples evaluated.
Can internal criteria be applied more strictly than the standard?
Yes, and many factories do this to create a safety zone. What needs to be done is to clearly state in the document which is the internal threshold and which is the standard threshold.
8. Conclusion
The set of standards for cross-sections is divided into three clear groups: test methods (IPC-TM-650 2.1.1), board technical requirements (IPC-6012, IPC-6013, IPC-6016) and acceptance criteria (IPC-A-600, IPC-A-610, and J-STD-001 for soldering). For BGA, IPC-7095 is a specialized document that requires separate reference.
Three things to do: clearly separate the two groups “how to” and “criteria” in every report; Always write the model number and year of issuance; and finalize product grades with customers before evaluation.
References
- IPC-TM-650 Method 2.1.1 — Microsectioning.
- IPC-A-600 — Printed circuit board acceptance criteria.
- IPC-6012 — Technical and performance requirements for rigid printed circuit boards; IPC-6013 for soft board; IPC-6016 for high density boards.
- J-STD-001 — Requirements for electrical soldering and electronic assembly.
- IPC-A-610 — Electronic Assembly Acceptance Criteria; IPC-7095 — BGA design and assembly.
Related articles
- Cross-section in aviation and military: request records and retrieval
- IPC-7095: void criteria for level-specific BGA
- Two Laboratories, Two Different Results: Why?
- 10 circuit board defects can only be detected by cross-section
- Cross-section QFN/DFN: void under the heat sink and solder pins
- Cross-section BGA: void measurement and head-in-pillow detection
- Cross-section solder joint: wetting angle, fillet penetration and intermetallic compound (IMC) layer
- IPC-TM-650 2.1.1: standard microsection procedure
- IPC-A-600 and IPC-6012: cross-section board acceptance criteria
- J-STD-001 and IPC-A-610: evaluation of solder joints through cross-section
- What is Cross Section? Why do we have to cut samples to evaluate solder joints and circuit boards?
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Disclaimer
This article is an interpretive content compiled by us; not legal advice. Enterprises need to compare relevant documents/standards verbatim before applying them to specific products.
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