Cross sections are technically the same in every industry. But when products go into cars or medical devices, the requirements around that testing change dramatically: frequency, records, traceability, and how to handle changes.
This article compares the requirements between the two industries and what businesses need to prepare before joining their supply chains.
1. Why are these two industries more demanding?
- Consequences of error: Defective products can harm users, not only causing loss of revenue.
- Long life cycle: The product must operate stably for many years, even in harsh conditions.
- Traceability: every batch of material and every process change must be traceable.
- Strict change control: Small changes also require re-evaluation and may require customer approval.
- Quality records may be audited: results must be verifiable, not merely passing at the time of testing.
2. Comparing the requirements of the two industries
| Aspect | Automotive industry | Medical equipment |
|---|---|---|
| Main focus | Reliable under continuously varying vibration, temperature and humidity | User safety and stability of measurement or treatment function |
| Quality system requirements | Often associated with the automotive industry’s quality management system and customer requirements | Often associated with medical device quality management systems and product approval requirements |
| Change control | There is a strict change approval process, associated with documents proving process capacity | Have a revalidation process when materials, processes or suppliers change |
| Test records | Should be stored per batch according to an agreed control plan | Needs to be kept in product records and can serve inspection |
| Environmental testing | Heat, vibration, moisture, corrosion cycles | Heat and humidity cycling, electrical safety testing and biological stability where relevant |
Common point: both industries require test results to be attached to records and verifiable. A cross-sectional image without information about the sample, method and application level will not have enough value in the file.
3. How this affects the way cross sections are prepared
| Aspect | Common consumer products | Automotive or medical |
|---|---|---|
| Frequency of testing | Follow the first batch and when there is a problem | According to the agreed periodic plan, including any changes |
| Sample retention | Usually not kept | Samples and records should be retained for the committed period |
| Control sample | Recommended | Usually a mandatory requirement |
| Interpretation of results | Can be flexible according to experience | Needs to be linked to approved criteria and application levels |
| Photo documentation | Photo with description | The photo has a scale, clearly stating the magnification, position and cutting direction |
4. Which changes require re-evaluation?
This is a question that businesses often miss and is also the source of many complaints. Groups of changes that often need re-evaluation:
- Material change: Solder paste, flux, coatings, board materials.
- Supplier change: circuit boards, components, soldering consumables.
- Change equipment or process parameters: temperature profile, speed, pressure.
- Change of pad or stencil design: directly affects solder paste volume and solder joint shape.
- Change of production site or switch of supply chain.
With each change, it is necessary to re-determine whether the cross section results are still valid or not. In many cases, retesting is a condition to prove that the new process still meets requirements.
5. Documentation requirements
- Sample information: Product code, batch number, manufacturing date, sampling location.
- Test information: cutting position and direction, sample preparation method, magnification.
- Results: The image has a scale, measurement results, and conclusions for each indicator.
- Applicable criteria: agreed standards, quality levels, and thresholds.
- Device information: Calibration status of measuring equipment and microscope.
- Implementer and approver.
6. What to prepare before joining a supply chain
- Build internal processes based on standardized test methods, not based on personal experience.
- Establish a sample-retention rule and stipulate the retention period committed to customers.
- Build report forms with enough information fields to meet documentation requirements.
- Maintain equipment calibration and save documents.
- Train image reviewers to distinguish real defects from artefacts caused by sample preparation.
- Agree with customers on criteria, quality levels and thresholds before production.
7. Frequently asked questions
Is periodic cross-sectioning mandatory?
Usually specified in a quality control program agreed with the customer. With important products, periodic inspection is a way to prove that the process is still under control.
Are old results still valid after a material change?
No. Changing materials is one of the most common causes of changes in solder joint properties, so re-evaluation is needed.
Do we need to keep the samples after cutting?
It is advisable to retain at least the mounted cross-section sample. Retained samples help answer questions that arise later without having to re-prepare a sample.
Can a small factory meet the documentation requirements?
Yes, if suitable processes and forms are in place. Most requirements concern consistency and verifiability, not equipment scale.
Where should we start?
By standardising the sample-preparation process and developing reporting forms. These are the two factors that most affect the ability of both industries to meet documentation requirements.
8. Conclusion
Cross section technical requirements do not vary across industries. What changes is the stringency of frequency, documentation, traceability and change control. With automotive products and medical devices, test results must be verifiable, not just correct.
Four things should be done: standardize sample preparation procedures; Build a report form with enough information fields; Maintain sample and calibration records; and clearly identify which groups of changes need to be reevaluated so that they are not missed.
References
- IPC-TM-650 Method 2.1.1 — Microsectioning.
- IPC-A-610 — Electronic Assembly Acceptance Criteria.
- J-STD-001 — Requirements for electrical soldering and electronic assembly.
- IPC-6012 — Technical requirements for rigid printed circuit boards.
Related articles
- Technical Cleanliness Testing per VDA 19.1: 7 Steps from Cleanliness Specification to Result
- Cross-section in aviation and military: request records and retrieval
- IPC-A-600 and IPC-6012: cross-section board acceptance criteria
- 7 situations where factories are forced to do cross-sections
- Measuring dimensions on cross-sectional images: how to set the ruler to minimize the error?
- Set of standards governing cross-section: IPC-A-600, IPC-6012, IPC-TM-650 2.1.1, J-STD-001 and IPC-A-610
Talk to us
Disclaimer
This article is interpretive content compiled by us; it is not legal advice. Enterprises need to compare relevant documents/standards verbatim before applying them to specific products.
Learn more: Copyright Policy & Disclaimer at ticforall.com.
