Failure cause and Common Detection Methods of Electronic Components

Date：2023-07-21 17:50:00Views：399

Electronic components refer to finished products that do not change their molecular composition during factory production and processing, usually composed of multiple parts. The family of electronic components is very extensive and huge, including complex resistors, relays, capacitors, transformers, Potentiometer, electronic tubes, radiators, electromechanical components, Potentiometer, connectors, etc. In the electronic circuit, the resistors, capacitors, inductors and transformers that people most often contact, because of their importance, this article will focus on explaining their Failure cause and common detection methods.

1. Resistor class

Resistors, as the name suggests, can play a current limiting role in circuits. Additionally, resistors can generate heat through the thermal effect of current, and are commonly referred to as resistors in daily life. They are energy consuming components. The commonly used bulbs, heating wires, etc. can all be represented as resistors.

Resistors are widely used in electronic devices, and the rate of electronic device failures caused by resistor failures is relatively high, accounting for about 15% according to statistics. The failure modes and causes of resistors are closely related to the structure, process characteristics, and usage conditions of the product. There are four types of resistor failures:

(1) Lead breakage, substrate defects, poor film uniformity, film groove defects, poor contact between film material and lead end, film substrate contamination, etc.

(2) Uneven resistance film, broken resistance film, loose leads, decomposition of resistance film, silver migration, oxide reduction of resistance film, electrostatic charge effect, lead breakage, corona discharge, etc.

(3) Poor contact, current corrosion, loose leads, poor wire insulation, solder melting, etc.

(4) Poor contact, poor welding, contact spring rupture or lead detachment, impurity contamination, poor epoxy adhesive, shaft tilt, etc.

(5) Burnout caused by poor heat dissipation, excessive humidity, or manufacturing defects

(6) The circuit is abnormal, such as resistance burning caused by short circuits, overloads, and other reasons.

(7) Contact pressure is too low, spring stress is relaxed, sliding contacts deviate from the track or conductive layer, mechanical assembly is improper, or significant mechanical loads (such as collisions, drops, etc.) cause deformation of the contact spring.

(8) The conductive layer or contact track forms various non-conductive film layers at the contact point due to oxidation and pollution.

2. Capacitor type

Capacitors, also known as "capacitors", are devices that hold charges and belong to energy storage devices. The simplest structure of a capacitor can be composed of two adjacent metal plates sandwiched with an insulating medium, so the type of capacitor is mainly determined by the electrode and insulating medium.

The common faults of capacitors mainly include breakdown, open circuit, degradation of electrical parameters, electrolyte leakage, and mechanical damage, which are closely related to various factors such as material types, structural differences, manufacturing processes and environmental conditions, and working stress. The main reasons for these faults are as follows:

(1) Breakdown. There are defects, defects, impurities, or conductive ions in the medium; Aging of dielectric materials; Electrochemical breakdown of dielectric; Edge flashover between poles in high humidity or Low-pressure area environment; Instantaneous short circuit of dielectric under mechanical stress; Metal ions migrate to form conductive channels or edge flashover discharges; The air gap breakdown inside the dielectric material causes the dielectric Electrical breakdown; Mechanical damage to the medium during the manufacturing process; The change of the molecular structure of the dielectric material and the applied voltage is higher than the rated value.

(2) Open circuit. Breakdown causes insulation of electrodes and leads; The anode lead foil of Electrolytic capacitor is corroded and broken (or mechanically broken); Low level open circuit caused by the oxide layer at the contact point between the lead wire and the electrode; Poor contact or insulation between the lead wire and the electrode; Open circuit caused by corrosion of metal foil led from anode of Electrolytic capacitor; Drying or freezing of working electrolytes; Instantaneous open circuit between electrolyte and dielectric under mechanical stress.

(3) Degradation of electrical parameters. Moisture and dielectric aging and thermal decomposition; Metal ion migration of electrode materials; The existence and variation of residual stress; Surface pollution; The self-healing effect of the metallized electrode of the material; Volatilization and thickening of working electrolytes; Electrolytic or chemical corrosion of electrodes; The contact resistance between the lead and electrode increases; The influence of impurities and harmful ions.

(4) The temperature stress in the circuit promotes surface oxidation, accelerates the impact of aging, accelerates the degradation of electrical parameters, and in turn, promotes a decrease in electric field strength, accelerating the early arrival of dielectric breakdown.

3. Inductive coil type

Inductive coil is a device that uses the principle of electromagnetic induction to work. It is an energy storage component that can convert electrical energy into magnetic field energy and store energy in the magnetic field.

There are many reasons for the burnout of inductance coils, and we can consider prevention from the following factors:

(1) In order to reduce production costs, manufacturers have used enameled wires with a temperature resistance of below 130 ℃~150 ℃ due to quality issues with enameled wires.

(2) The problem of reaction force coordination between the suction forces of inductance coils; When the voltage is low, it becomes difficult to pull in. The action time of the inductance coil is long, and the time it bears the strong starting current becomes longer, which further heats the inductance coil and makes the suction force more obvious, making it more difficult to pull in until it cannot be pulled in. The inductance coil operates at high temperatures, leading to an increase in resistance and a very high current.

(3) The working voltage range of the product design is not wide enough. Once the voltage is between 80% and 85%, there may be a situation where the hot state cannot be closed. When the voltage is higher than 120%, the inductance coil is prone to overheating.

(4) Poor or out of control during the production process; During production, the inner layer of the winding of the inductance coil is not fully immersed in paint and not thoroughly dried, which can easily cause poor welding and incomplete insulation of the winding lead joints, resulting in inter turn and inter layer short circuits and loss of insulation.

(5) There are deficiencies in the winding process of inductance coils; During the production of the winding machine, the winding force should not be too loose or too tight, otherwise it will elongate the enameled wire and cause local insulation and voltage resistance to decrease.

(6) During use, if the insulation part of the inductance coil is damaged or mechanically damaged, resulting in inter turn short circuits or grounding, a large short-circuit current will be generated in the inductance coil, causing a sharp increase in temperature and transferring heat to adjacent wire turns, ultimately potentially burning the entire coil.

(7) Human factors; When users are not familiar with the use of non inductive coils, incorrect voltage regulation often occurs; The installation process is poor, and the inspection of the inductance coil is not careful, resulting in the inclusion of other impurities in the inductance coil. The operation and maintenance are not in place, and the relevant usage techniques are not strictly followed. During the period from installation to burning, most inductance coils have not undergone routine maintenance and dirt treatment, resulting in poor heat dissipation conditions and burning.

4. Transformer class

A transformer is a device that uses the principle of electromagnetic induction to change the AC voltage. The main components are the primary coil, secondary coil, and magnetic core. Generally speaking, a transformer has two or more windings.

In terms of current technology, there are two factors that have the greatest impact depending on the transformer model: the use of insulation materials and temperature.

(1) Using Materials

The insulation material used for the transformer must meet the requirements of high temperature resistance, water resistance and oxidation resistance, because the transformer has been operating in a harsh environment for many years. Under the action of electricity, heat, chemistry and electrodynamics, the insulation material is easy to exceed a certain limit and gradually lose its original mechanical and insulation properties and gradually age, So it can be said that the basic lifespan of transformers can be determined in a certain sense by the high-temperature resistance, waterproof, and antioxidant properties of insulation materials.

(2) Temperature

Practice and research have shown that there is an 8 ℃ rule for the relationship between the working temperature and lifespan of transformers: when a transformer operates for a long time beyond the temperature rise limit, the service life of the transformer is shortened by half for every 8 ℃ increase.

The above is the electronic component related content organized by Chuangxin Testing editor, hoping to be helpful to you. Our company has a team of professional engineers and industry elites, with three standardized laboratories covering an area of over 1800 square meters. We can undertake various testing projects such as electronic component testing and verification, IC authenticity identification, product design and material selection, failure analysis, functional testing, factory incoming material inspection, and tape weaving.