Yazaki Domestic Connector Metal Shell Peeling Treatment Guide

In fields such as automotive electronics, rail transit, and power equipment, connectors are not only responsible for transmitting current and signals but also for various functions such as structural protection, dust and water resistance, and vibration resistance. Taking Yazaki brand connectors as an example, their product shells are mostly made of plastic or metal materials, and surface coating and anti-corrosion treatments are applied to cope with complex working conditions.

When we find the phenomenon of "peeling of the metal shell" in domestic substitute connectors, that is, the stripping, blistering, and falling off of the plating or surface metal protective layer, we must attach great importance: because this means that the corrosion resistance, rust prevention, and electromagnetic shielding functions may be damaged, and the long-term reliability may decrease. Below, combined with Yazaki product characteristics and the peeling phenomenon, we will gradually analyze the causes of the problem, the methods of treatment, and the preventive measures.

One, Yazaki brand connector metal shell/case material situation
Although Yazaki's shells are more often made of plastic materials (such as PBT, HPA, etc.) for general connector series.
●But in some high-end applications (such as EV charging connectors), the instruction documents mention "metal part within the housing" — a metal part inside or part of the housing structure.
Although the specific description of "peeling of the metal shell coating" was not found, the reliability design ideas can be借鉴 from the classic failure modes in the connector industry (such as peeling of the metal shell shield cover, coating failure).

Therefore, when domestic connectors are designed with metal housings (or metal shielding covers), key controls must be implemented over the coating of the shell, anti-corrosion processes, anti-peeling procedures, and the way of structural adhesion.

The main reasons for the peeling of metal shell bodies
Coating quality does not meet standards
Nickel plating, zinc plating, nickel-palladium plating, or anodizing layer may peel off under thermal cycles, humidity, and vibration if the adhesion is poor, the thickness is insufficient, or the pretreatment (such as degreasing and activation) is not adequate.
Large structural stress or thermal expansion differences
The thermal expansion coefficient difference between the metal housing and the plastic/rubber sealing and connecting parts is large, which can lead to peeling, cracking, and coating detachment after repeated thermal cycles (such as -40℃→+125℃).
Corrosion environment or humid aging
●In high humidity, salt fog, road chemical splashes, and undercarriage corrosion environments, if the coating or protective layer of the metal shell fails, it will directly expose the metal substrate and cause oxidation and scaling.
4. Mechanical damage or assembly injury
●Tugging, scraping, impact, and excessive force on clips during assembly may damage the coating adhesion, making it easier to peel off under vibration or temperature cycling.
5. Domestic substitution design or technology control is insufficient.

When replacing domestic products, if low-cost shell materials are directly used or the plating process is reduced to reduce costs, while ignoring the process margin in structural protection and lifespan design of brands like Yazaki, reliability issues such as peeling will be exposed.

What to do if it peels off? Processing steps
Recommend the following treatment process for the peeling phenomenon of metal shells:
On-site inspection and record
Remove the connector housing or observe the peeling area: record the location of peeling, the area of peeling, whether accompanied by base material corrosion, whether accompanied by cracks, and whether it affects the internal electrical/mechanical components.
Simultaneously detect contact resistance, insulation resistance, and voltage withstand conditions, and determine whether the peeling has affected the function.
Clean the peeled area
●Remove peeled coatings, oxides, and rust using a non-metallic brush or soft cloth. Avoid using hard brushes or metal brushes as they may further scratch the base material.
If the base material is exposed to rust or corrosion marks, anti-rust treatment should be carried out: such as spraying anti-rust primer or using phosphatizing treatment.
3. Replate or replenish the protective layer
For repairable parts, it is recommended to replate (such as nickel plating, zinc plating) or apply high-corrosion-resistant coatings after cleaning.
If the connector is a mass-produced item, it is recommended to replace the housing or the entire connector. A permanent identification label should be attached to the repair parts for traceability.
Structural repair and sealing enhancement
Check for gaps or loose interfaces between the metal housing and plastic/seal parts. If found, resecure, bond, or replace the clips.
For waterproof/dustproof connectors, it should also be supplemented with sealing rings and replacement of aged sealing parts.
5. Function retest
●Perform contact resistance, insulation resistance, voltage withstand test, vibration/thermal cycle sample test again after repair. Ensure that the repaired connector still meets the design requirements.
●If used for automotive applications, it should consider thermal cycling (-40℃～+125℃), salt spray, and humid heat aging tests.
Root Cause Analysis and Improvement
● Investigate the reasons for peeling: is it due to poor plating technology? Is it thermal cycle stress? Is the corrosion environment beyond the design? Then modify the process specifications for future procurement and domestic alternatives.

For domestic substitution, it is necessary to formulate anti-peeling layer requirements slightly higher than or at least consistent with Yazaki specifications, and include coating adhesion, thermal cycle stripping rate, and corrosion testing in the acceptance standards.

Four, preventive suggestions: how to avoid the shell peeling in domestic substitution
In the selection stage, it is recommended to include metal shell connectors (or those with metal shielding) in the category of key structural components, and require suppliers to provide: coating thickness, adhesion test (such as tensile test), thermal cycle peel rate, and salt spray test report.
●It is recommended to specify in the domestic alternative specifications: the剥落area of the housing coating ≤ X mm², with no cracks or peeling after 100 thermal cycles.
It is recommended to strengthen the structural design: avoid excessive thermal expansion differences between the shell, seals, and parts of different materials; reasonably design the pre-pressure of the sealing rings; and control scratching or indentation during the assembly process.
Establish assembly process protection measures: Avoid scratches on metal casings from sharp devices during production line operations, and prevent wet rot environment during transportation/storage.

Establish a tracking system: Once skin issues are found, establish batch number records, maintenance archives, and improvement feedback mechanisms.

The metal shell peeling, which appears to be a "surface" issue, may actually be a隐患 chain leading to performance risks: from shielding failure, corrosion failure, to mechanical structure loosening, and poor electrical contact. Taking brands like Yazaki as a standard, we cannot just focus on "looking good" in the process of domestic substitution. We should start from the whole chain of materials, coatings, structure, environmental adaptation, post-assembly protection, and after-sales tracking. Only through strict prevention, timely handling, and root cause improvement can we truly achieve that "domestic substitution" is not just a change of brand, but a more reliable, more controllable, and more durable one.
If you are interested in the domestic substitute products for Yazaki brand connectors or have procurement needs, or if you have production or sales channels for these brand connector domestic substitutes and wish to engage in in-depth cooperation or communication, please contact via the following contact information:Manager Zhang (18665383950, WeChat number the same)Contact us, we look forward to working together with more industry partners.