1、 Skeleton effect
The effect of skeleton in transformers mainly includes the following points:
1. Provide surrounding space for the copper wires in the transformer,
2. Fix the magnetic core in the transformer.
3. The wire slot in the skeleton serves as the path for the transformer to pass through during winding production.
4. The metal pins in the skeleton are pillars surrounded by copper wires of the transformer; After soldering, it is connected to the PCB board to achieve conductivity during transformer operation.
5. The convex, concave, or chamfered points in the skeleton can determine the placement direction or pin order of the transformer during use.
6. The retaining wall at the bottom of the skeleton can fix the transformer and PCB board; Provide a certain metric space for the tin stack and PCB board, and the magnetic core and PCB board during soldering; Block the magnetic core from the tin stack to avoid poor voltage resistance.
7. The convex, concave, or chamfered points in the skeleton can determine the placement direction or pin order of the transformer during use.
2、 Transformer skeleton classification
Skeletons are generally classified according to the type of magnetic core (or iron core) used in transformers, including EI, EE, EF, EPC, ER, RM, PQ, UU, etc. Each type can be distinguished by the size of the magnetic core (or iron core), such as EE5, EE8, EE13, EE19, and other types with different sizes. The skeleton can be divided into two types according to its shape: vertical and horizontal; According to the operating frequency of transformers, they can be divided into two types: high-frequency skeleton and low-frequency skeleton. The frequency mentioned here does not refer to the number of times the transformer is used, but rather the number of times it periodically changes during operation. The unit is Hertz (Hz), abbreviated as Hertz, which is also commonly used as kilohertz (kHz), megahertz (MHz), or GHz; According to the nature of the stitch application of the skeleton, it can be further divided into two types: direct insertion skeleton (DIP) and SMD skeleton.
It is precisely because the skeleton has so many features that its shape can be described as ever-changing. In terms of the same skeleton, for example, the EE-13 straight plug bakelite skeleton, after such a detailed classification, its Viper skeleton has reached as many as 36 types. Some have different heights of retaining walls, while others have different dimensions of winding slots. Even the most important and critical dimensions, PIN spacing and row spacing, are not the same. This creates many difficulties for both the supply and demand sides of the skeleton. If the scale is slightly different, the existing molds cannot be used. For simpler ones, it is necessary to collaborate on a certain part of the newly opened mold, while for more complex ones, the entire mold must be reopened. This has greatly increased the production cost of transformers. In the industry, due to the inability to find suitable molds, transformer factories are often unable to accept orders. Many friends from transformer factories have a consensus that among all the components of transformers, the skeleton is the most difficult to find. Regarding the skeleton factory, we have developed many sets of molds ourselves, but due to the lack of orders placed on shelves, we are unaware that some transformer factories have abandoned their orders due to the inability to find molds for this product.
3、 Planning and Manufacturing of Skeleton Product Mold
This process generally plans the specific structure of the skeleton according to the requirements of the customer (transformer manufacturer), mostly planning the skeleton for the customer, and the skeleton manufacturer directly molds according to the planned skeleton. But there are also a few cases where customers provide samples or simple planning diagrams, and the skeleton manufacturer cooperates to complete the preliminary planning tasks. When planning the skeleton, attention should be paid to the following details to reduce some defects that often occur during production.
In the early stage of skeleton planning, planners need to have a clear understanding of the application of the skeleton at the customer's location. Including the customer's requirements for finished transformer products, such as external dimensions; The production process of transformers and the production conditions of each process, such as soldering temperature, soldering time, baking temperature, winding method, etc; The type and size of the magnetic core that collaborates with this skeleton. In short, the precautions for using the skeleton on the client side must be understood clearly in order to better carry out the following planning tasks.
2. When planning the skeleton structure, it is necessary to use 3D models as much as possible based on the drawings or samples provided by the customer, combined with one's own planning experience, to avoid the shortcomings of 2D drawing and correction, and then gradually make corrections to ultimately finalize the decision. If the customer's planning is unreasonable, it should be automatically proposed to confess the skeleton structure from scratch with the customer's technical personnel.