In high-reliability applications (such as communication cabinets, power equipment, rail transit, and military systems), the environmental adaptability of connectors is crucial. Thermal shock tests are a regular project to evaluate whether connectors can maintain their electrical performance, mechanical reliability, and shielding/filtration effects under severe temperature changes. This article discusses the general practices of domestic connectors in terms of passing the thermal shock tests, factors that determine the pass rate, and key points to pay attention to in the testing and mass production introduction stage, combining the specifications of APITech (API Technologies) series filter/high-reliability connectors.
APITech related specifications and reliability reference (including judgment criteria)APITech's filtering and integrated connector series typically provide a wide operating/storage temperature range in product specifications (for example, common operating temperature can reach up to -55°C to +125°C), and its high-temperature product line can also meet more stringent long-term high-temperature requirements (some high-temperature EMI products claim to meet higher temperatures and MIL category tests). These specifications set a target baseline for evaluating domestic substitutes.
High and low temperature shock test refers to a test method in which the specimen is subjected to rapid changes in temperature, simulating the actual working conditions of high and low temperature environments. The common criteria for judgment include:
1. Appearance inspection: After the test, the surface of the specimen should not have cracks, blisters, delamination, or other defects.
2. Dimensional change: The change in dimensions of the specimen should meet the requirements of the design specifications.
3. Mechanical properties: The mechanical properties of the specimen, such as tensile strength, yield strength, and elongation, should meet the requirements after the test.
4. Functionality: After the test, the specimen should still maintain its normal function.
Commonly used criteria include:
1. ISO 16749-1:2012: This standard specifies the requirements for high and low temperature shock tests on automotive parts.
2. GB/T 2423.44-2008: This standard specifies the requirements for high and low temperature shock tests on electronic products.
3. MIL-STD-810G: This standard specifies the environmental test methods for military equipment, including high and low temperature shock tests.The high and low temperature shock test aims to simulate the situation where equipment experiences extreme temperature changes within a short period (such as rapidly rising from -55°C to +125°C), and to test whether indicators such as contact resistance, insulation resistance, shielding grounding continuity, integrity of filter components (capacitors/inductors), and mechanical insertion and extraction life deteriorate or fail. Common measurement points include:
● Electrical performance indicators: Whether the contact resistance and insulation impedance are within the allowable range before and after the test; whether there is a significant change in the insertion loss/differential-mode-common-mode characteristics of the filter.
● Mechanical reliability: whether the insertion and extraction mechanism is stuck, whether the contacts are oxidized or fall off, and whether the shell has cracks or seal failure.
● Appearance/Sealing: Check for cracks, weld point cracking, insulator deformation, etc.
The industry and military standards will specify the specific number of cycles, rise and fall rates, and insulation duration. The equipment will be deemed passed or failed based on whether "the critical electrical/mechanical indicators still meet the requirements."
Domestic connectors usually can withstand how many cycles of high and low temperature shock?The answer is not a single number; it depends on multiple variables. The following provides empirical judgments according to different types and maturity levels.
Mid-to-low-end, general-purpose domestic connectors that have not been specifically high-temperature screened
●Typical situation: The materials and processes of these products are mainly for normal/extended temperature operation (e.g., −40°C~+85°C), and no special reinforcement is made for rapid temperature change.
● Test Passability: Under strict -55°C ↔ +125°C large amplitude shock conditions (military or aerospace grade solutions), it is likely difficult to pass more than 5-10 shock cycles, with the main reasons being micro-cracks on contact surfaces, cracking of solder joints or adhesive components, and unstable shielding contacts.
●Recommendation: More stringent screening tests and material improvement should be carried out before import.
2) Specifically claims domestic high-reliability models with wide temperature/impact resistance
●Typical cases: Some domestic manufacturers have launched improved materials (high-performance plastics, coatings, sealing rings) and improved structures (enhanced shell contact surfaces, double sealing) for power, rail, communication, and other scenarios.
●Test Through Capability: Under reasonable design and qualified process, it can pass 10-30 cycles even more, and electrical performance degradation is controllable. However, to achieve long-term indicators recognized by MIL-level or military, such as +175°C/1000 hours lifespan, still requires a large amount of verification and third-party certification. APITech and other imported brands have already had publicly verified high-temperature product line cases in such high-temperature/lifespan tests, and domestic substitutes need to catch up with this goal step by step.
3) APITech level imported high-end filter connector
●Typical cases: Their product matrix usually includes series that have passed strict environmental tests (with specifications for operating temperature range, thermal shock, vibration, salt spray, and welding reliability, etc.). Imported high-end products have mature verification in structural design, selection of filtering devices, and material consistency.
● Test capability: Generally able to pass the multi-cycle thermal shock and long-term high temperature life tests specified by the standard (the number of cycles and insulation time are based on the specific standard). This is also a "benchmark" for the domestic substitution assessment.
Key factors affecting the thermal shock pass rate of domestic connectorsContact and plating process: Contact plating (such as nickel/gold thickness) and matrix material have a significant impact on the fatigue resistance to temperature cycling.
The selection of filtering components and packaging: Capacitors and inductors in filters are prone to failure under thermal cycles (such as capacitor cracks and pin desoldering). High-temperature grade capacitors and strict packaging can significantly improve the pass rate.
Shell and Seal Design: The material of the sealing ring and the compression method determine whether the seal and shielding contact are maintained during thermal expansion and contraction.
Welding/assembly quality: the thermal fatigue life of weld joints and the assembly process directly determine long-term stability.
Design margin and testing verification: Reserving thermal stress margin and conducting accelerated life tests (HALT/HASS) can help identify potential failure modes and improve them.
Importing Practical Suggestions for Domestic Substitution (Aimed at Procurement and R&D)●Prior to purchasing replacement parts, it is required to provide thermal shock/temperature cycling test reports and batch application cases.
●Perform pre-and-post comparison tests of key indicators (contact resistance, filter insertion loss) at the prototype stage, and use near-field measurement/spectrum analyzer to locate possible shielding degradation.
●Designing fixture and assembly processes together with suppliers to reduce welding and mechanical stress concentration.
If the project is a critical long-term operation (such as equipment operating under normal conditions in a high-temperature environment), it is recommended to conduct accelerated life tests and sign reliability assurance clauses.
The number of rounds that domestic connectors can pass in high and low temperature shock tests does not have a unified answer: it depends on the product design, materials, component selection, and process maturity. Faced with the APITech-level imported high-end filter connectors, domestic alternatives need to achieve the same or higher level in aspects such as contact plating, filter component selection, shell sealing, and assembly process in order to match their performance in thermal shock and long-term high temperature stability, and use system-level test data to support mass production introduction. Reasonable prototype verification, third-party testing, and gradual mass production trial production are the necessary path to achieve stable replacement.
If you are interested in the domestic substitute products of APITech brand connectors or have procurement needs, or if you have production or sales channels for such brand connectors and wish to engage in in-depth cooperation or communication, please contact via this contact method:
Manager Zhang (18665383950, WeChat same number)Contact us, we look forward to working together with more industry partners.
