Failure analysis of polymer materials
Failure analysis of polymer materials
Failure may occur at all stages of the product life cycle, involving product R & D and design, incoming inspection, processing and assembly, test screening, storage environment, customer use and other links. WSCT confirms the failure mode, analyzes the failure mechanism, defines the failure reason, and finally gives preventive countermeasures to reduce or avoid the recurrence of failure by analyzing the samples of process waste, early failure, test failure, pilot test failure and field failure.
Service background
Failure analysis is of great significance to the production and use of products. Failure may occur at all stages of the product life cycle, involving product R & D and design, incoming inspection, processing and assembly, test screening, storage environment, customer use and other links.
WSCT confirms the failure mode, analyzes the failure mechanism, defines the failure reason, and finally gives preventive countermeasures to reduce or avoid the recurrence of failure by analyzing the samples of process waste, early failure, test failure, pilot test failure and field failure.
WSCT failure analysis service relies on hundreds of cutting-edge analytical instruments in professional laboratories, supplemented by technical experts' extensive experience in polymer materials and failure analysis, to ensure that the analysis results are fair, professional and objective, so as to help customers improve product quality and technology.
Failure analysis object
Plastic rubber Natural latex an adhesive
Unknown Metal materials and products Auto parts compound material
coating oil fine chemicals Inorganic matter
PCB Electronic components Welding products LED products
service content
Failure analysis generally includes failure background investigation, analysis scheme design, result analysis and discussion and other steps. During the analysis process, we will fully communicate with customers to ensure the accuracy of the results.
1、 WSCT uses comprehensive diversified analysis and testing methods to directly explore the main and most likely causes of failure:
1. Design a unique analysis scheme according to the characteristics of failure and products.
2. Comprehensive use of various analysis and testing methods, including but not limited to micro morphology analysis, composition analysis, performance analysis and reproducibility test.
3. Comprehensively compare and analyze the failed products, infer the causes that may lead to the failure or eliminate the factors that affect the failure.
4. Provide improvement countermeasures and suggestions to reduce or avoid the recurrence of failure.
2、 Specific process of service:
1. Failure background investigation: product failure phenomenon, failure environment, failure stage (design and commissioning, pilot test, early failure, medium-term failure, etc.), failure proportion, failure historical data, etc.
2. Non destructive analysis: X-ray fluoroscopy, ultrasonic scanning, electrical property test, morphology inspection, local component analysis, etc.
3. Destructive analysis: unsealing inspection, profile analysis, probe test, focused ion beam analysis, thermal performance test, body composition test, mechanical performance test, etc.
4. Analysis of service conditions: comprehensive analysis of structural analysis, mechanical analysis, thermal analysis, environmental conditions, constraints, etc.
5. Simulation and verification experiment: according to the failure mechanism obtained from the analysis, a simulation experiment is designed to verify the failure mechanism.
6. Give reasons for product failure and provide suggestions or solutions for improvement.
Common causes of product failure
1、 Replace the raw material supplier or the quality control problem of the raw material supplier, resulting in the failure of batch products caused by the difference between batches of raw materials.
2、 Temperature / humidity changes, seasonal changes, resulting in product failure in the production or use process.
3、 Product failure caused by process problems in the production process.
Common product failure modes
1、 Deformation, fracture, cracking, wear, falling off, delamination and blistering;
2、 Frost spray, oil spray, powder spray, precipitation and foreign matters;
3、 Corrosion, chalking, aging, discoloration, etc.
Failure cases
Case 1 - cracking
1. Background introduction
The customer's product is the black plastic frame of mobile phone parts, which is made of PC and glass fiber blend, and the surface is coated with primer and UV curing varnish. The frame cracks about 2 months after production.
2. Scheme and verification
The WSCT failure team puts forward a verification scheme according to the customer's samples and cracking conditions:
(1) Material analysis: confirm whether cracking is caused by material change according to the comparison of failure samples, normal samples and granular materials.
(2) Fracture analysis: analyze the fracture surface of the failure sample to find the failure reason from the microstructure.
(3) Ash analysis: determine the ash content of the sample according to the glass fiber and unknown particles found in the section to confirm the glass fiber content.
(4) Physical property analysis: analyze the melt mass flow rate of the sample to confirm whether there is the possibility of degradation.
3. Results and conclusions
(1) PC has a large number of uniform micropores, and significantly increases the melt mass flow rate. There is a greater possibility of degradation of PC on the surface, resulting in a reduction in strength.
(2) Glass fiber is added to PC for reinforcement, but the bonding between glass fiber and PC is poor, which makes PC unable to effectively coat glass fiber to improve strength.
(3) The fracture source of the failed sample is at the corner of the structure, where the stress is relatively concentrated. Because the strength is not enough to resist this stress concentration, after a long time of action, microcracks appear, and then crack propagation leads to the cracking of the sample.
(4) There is no significant difference in the principal components between failure samples, normal samples and granular materials; However, there are obvious differences in the composition of the reinforcing components. Compared with the raw materials, the finished products after injection molding not only have glass fiber, but also have a significant increase in TiO2 content, but the increase of this component has little correlation with the spraying process.
4. Analysis and suggestions
(1) During PC injection molding, the moisture content of pellets needs to be strictly controlled, and the pellets need to be fully dried before they can be used for injection molding.
(2) Improve the combination of glass fiber and PC.
(3) Anneal the injection molded products to reduce the residual internal stress.
Case 2 - corrosion
1. Background introduction
The customer's sample is PCB electronic devices, which are packaged with two-component epoxy adhesive. Out of cost considerations, the customer wants to introduce a second cheap supplier, and it is found that the two-component epoxy adhesive provided by the supplier has serious through-hole corrosion on the surface of PCB. The customer wants to find out the cause of corrosion, and entrusts WSCT to conduct failure analysis and investigation.
2. Scheme and verification
WSCT puts forward and verifies the general technical scheme for customers' problems:
(1) Analyze the composition of epoxy adhesive used in normal parts and failed parts.
(2) Analysis of surface morphology and surface composition of failed electronic devices.
(3) GC-MS analysis of two-component epoxy adhesive cured parts.
3. Results and conclusions
(1) By analyzing the surface morphology and composition of the corrosion location, it is also found that there is obvious information of modified amine curing agent in the corrosion location, which can also be inferred that it is caused by the corrosion of amine curing agent.
(2) The crosslinking degree of the two-component epoxy adhesive of the new supplier's product after curing is low. At the same time, it is detected that there are many kinds and quantities of small molecules of amines, and the amine curing agent is easy to migrate. Contact with the circuit board will lead to corrosion.
(3) The aromatic solvent oil in the two-component formula of the new supplier is more different from the formula of the original supplier in composition. The aromatic solvent oil has swelling effect on the cured parts, resulting in easier migration of small molecular substances.
