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Cracks on power inductors, and solutions | joinwin popularised science

Cracks on power inductors, and solutions | joinwin popularised science

July 31 , 2023 0

In some cases, we find some visible cracks (thin lines) on the power inductors. Usually we would think that this is a quality issue and we would wonder ah why these inductors have these cracks. But the fact is that actually these power inductors are not damaged, scientifically speaking. --joinwinchips
Most of the power inductor cores circulating in the market are not a single solid block: e.g. the whole silicone material/iron material, but moulded power inductors. It actually means that the original manufacturer is producing a mixture of iron powder and resin binder that is extruded and punched and moulded around the inductor coils through processing.
From the point of view of the absolute majority of uses, we certainly want all products (especially electronic components) received intact at least look intact. Currently, due to the limitations of the process, it is still difficult to ensure that the core material can be manufactured in a flawless manner while still being processed. But don't worry, regardless of whether there are cracks on the surface of the moulded power inductors or whether they look flawed, we can certainly guarantee that each moulded power inductor passes all industry standard tests (including tests for thermal shock, mechanical shock, terminal strength, vibration, humidity, moisture resistance, service life, etc.). Mere cosmetic imperfections do not affect the reliability of our products or may have an impact on the performance of our products.

Hairline Cracks

Cracks around inductor cores are almost impossible to eliminate because the moulding process involves curing both the resin binder and the iron powder. During this process, small cracks can occur due to wall friction at discharge. Unlike ferrite power inductors, these

inductors may have slight to moderate and large cracks, but they do not affect the performance of the product. Hairline cracks should be less than one-third of the length of the "H" on the left and right sides of the terminals or they will be considered defective. The

"H" indicates the distance between the soldered terminal and the side of the material, as shown in the figure above.

Visual cracks on terminals

This picture shows an acceptable minor crack on the left side of the terminal.

This image shows an acceptable larger

crack on the right side of the terminal.

Both of the above diagrams show visual cracks, but these two cracks are within specification and can still be used because the crack length is less than 1/3 of the height "H" All other cracks must be less than the height "H" to be considered acceptable.

Cracks on marked surfaces

Any crack that appears on the top surface of the inductor is considered unacceptable.

Cracks on the surface of the pads

Cracks may also appear on the bottom surface near the pad surface. If the length of the crack is less than 2mm, the material is considered acceptable.

joinwin science 'what is power inductor'

A power inductor is an electronic component that can stably transfer current and regulate voltage in a circuit. It can filter out high-frequency noise and interference in the electrical signal, thus ensuring the stable operation of the circuit.

Classification of Power Inductors

Power inductors can be divided into three categories according to their structure: iron core inductors, air core inductors and hybrid inductors. According to its use can be divided into two categories: inductors for AC circuits and inductors for DC circuits.

Characteristics of Power Inductors

Power inductors are characterised by self-inductance, inductive resistance and low-pass filtering. They are widely used in circuits such as excitation converters, DC power supplies, and are often used to regulate parameters such as output voltage and current.