Self-locking Tuning Screw Helps the Stable Debugging of Communication Filter —— Suzhou Maite Technology Precision Fastener Solution

In communication equipment such as 5G base station, optical communication, satellite communication and RF microwave devices, cavity filters and dielectric filters play an important role in frequency selection, spurious suppression and signal purity. In the process of filter debugging, it is necessary to fine-tune the positions of resonant rod and coupling rod repeatedly to obtain accurate center frequency and insertion loss index, and tuning screw is the key part to fix the debugging result. Under the vibration, temperature cycle and long-term operation conditions of the whole machine, the traditional tuning screw is prone to loosening or displacement, which may lead to the frequency drift of the filter, the deterioration of standing wave ratio and the over-limit of channel index, and become a potential risk affecting the reliability of communication equipment. Suzhou Maite Technology Co., Ltd. focuses on the R&D and manufacturing of precision fasteners, and provides systematic solutions for self-locking tuning screws from product design, material selection, locking structure, batch consistency to assembly process matching around the tuning scene of communication filters, helping filter manufacturers stabilize debugging results and improve the long-term reliability of the whole machine.

First, filter tuning has higher requirements for fasteners.

The requirements of screws for filter tuning are obviously higher than those of ordinary fasteners. There are usually several tuning screws in the cavity filter, and the screwing depth of each screw will correspond to a frequency response, which needs to be kept in this position for a long time after debugging. The common thread structure mainly depends on the pre-tightening force to maintain the position. When the equipment experiences transportation vibration, engine room fan operation, outdoor alternating high and low temperatures and other working conditions, there may be slight relative rotation between the thread pairs. Even if the position change is only a few tens of microns, the filter index may deviate from the acceptable range.

At the same time, the tuning screw is usually in a high-frequency RF field, and the top of the screw extends into the resonant cavity. Its material, surface coating and geometric size will affect the electromagnetic field distribution and passive intermodulation index in the cavity. Therefore, the tuning screw needs to meet the requirements in four aspects: locking reliability, electrical performance, batch consistency and assembly convenience.

Second, the self-locking structure improves the long-term locking reliability

Aiming at the core problem that the tuning screw is easy to loosen, the self-locking tuning screw of Suzhou Maite Technology adopts the self-locking structure design of thread pair. By arranging elastic self-locking elements or special tooth shapes on the thread mating surface, the screw can form a continuous radial compression force after screwing in, and a stable friction locking effect can be obtained. This scheme can resist the risk of looseness caused by vibration and temperature alternation without additional glue dispensing, nut installation or marking.

Compared with the traditional thread glue locking method, the self-locking structure does not introduce the problems of glue layer aging, glue overflow polluting the cavity, and it is difficult to reset after disassembly. When the filter is repaired or debugged for the second time, the screw can be screwed out and screwed in normally, and it can still maintain a stable locking force after repeated use. The product has been verified by vibration test and temperature cycle test, which can keep the position stable under the condition of long-term continuous operation of the equipment, which is helpful to reduce the index drift and the proportion of after-sales repair caused by tuning displacement.

Third, materials and surface treatment match the electrical performance requirements

In terms of materials and electrical properties, the company can provide differentiated selection schemes according to different bands and power levels of filters. The base material can be brass, beryllium copper, stainless steel, etc., which is matched according to the customer's requirements for cost, strength and conductivity; The surface treatment can be silver plating, nickel plating, gold plating, passivation and other processes. The coating thickness is uniform and controllable, giving consideration to conductivity, oxidation resistance and wear resistance, and reducing coating wear caused by repeated debugging.

Aiming at the high power base station filter with sensitive passive intermodulation index, the whole process is controlled from the purity of substrate, the compactness of coating to the surface roughness of thread processing, so as to reduce the risk of intermodulation deterioration caused by contact nonlinearity. The end of the screw can be machined into different shapes such as flat head, pointed head, grooved, hexagonal socket, etc. according to the tuning requirements, so that the geometric shape of the top end extending into the cavity is consistent with the customer simulation model, avoiding the frequency offset caused by the shape deviation of the fastener, and helping the debugging engineer to obtain more predictable tuning effect in the assembly stage.

Fourth, batch consistency ensures the efficiency of mass production debugging

Batch consistency is a link that is easy to get out of control in the mass production stage of filters. If there are deviations in pitch, tooth profile and end length of the same batch of tuning screws, the frequencies corresponding to the same number of turns will be different, and the debugging personnel will have to explore again one by one, which will not only increase the debugging time, but also easily lead to scattered indicators.

Depending on CNC turning, precise thread rolling and automatic inspection of production line, Maite Technology implements full inspection or high-proportion sampling inspection of key dimensions such as thread pitch diameter, tooth profile angle, end size and total length, and combines with thread stop gauge, image measurement, coating thickness measurement and other means to ensure the stability of intra-batch and inter-batch dimensions. Stable fastener foundation accuracy is helpful for filter manufacturers to establish a standard debugging process card, which corresponds to the frequency according to the screwing depth, shortens the debugging time of a single machine, and improves the production line beat and the first pass rate.

Five, the assembly process and rapid proofing support

Assembly process matching is also an important part of the solution. In the early stage of the project, Maite Technology can participate in the customer structure review, make suggestions on cavity wall thickness, thread hole depth, tuning stroke, locking torque, etc., and provide special debugging tools, limiting sleeves and torque reference values when necessary, so as to reduce the risk of thread slipping or cavity damage caused by debugging personnel working by hand.

For the automatic debugging production line, we can provide the batch matching scheme and torque curve suggestion for the electric screwdriver, so as to ensure that the automatic tuning equipment is locked consistently in batch operation. The company supports small batch samples and rapid proofing, and cooperates with the development rhythm of new models of customers. The cycle from drawing confirmation to sample delivery is controllable, which helps to shorten the introduction time of new products.

Six, quality traceability and localization service response

In terms of quality system, Matt Technology manages the whole process of self-locking tuning screws from raw materials warehousing, heat treatment, surface treatment to finished product shipment, which can provide material certificate, coating test report and size test data to meet the management requirements of material traceability in communication equipment industry.

The technical team can help to analyze the reasons for the abnormalities in batch use, judge whether the problems come from fasteners, cavity threads or debugging process, and give targeted improvement suggestions. Relying on Suzhou's location advantage, the company can quickly respond to the supporting needs of communication devices, RF modules and base station equipment manufacturers in the Yangtze River Delta region, and do a good job of coordination between delivery and inventory.

With the continuous development of deep coverage of 5G network, millimeter wave devices, satellite communication terminals and private network communication equipment, filters are evolving towards high frequency, miniaturization and high power, which puts forward higher requirements for tuning accuracy and long-term stability. Suzhou Maite Technology Co., Ltd. will continue to deepen the field of communication precision fasteners, optimize the reliability of self-locking structure, the consistency of plating process and the processing capacity of micro-specifications, and help communication filter manufacturers improve debugging efficiency and reduce the risk of index drift with stable and reliable self-locking tuning screws and supporting assembly schemes, so as to provide reliable fastener support for long-term stable operation of communication equipment.