Contact measuring head for measuring thickness of surface mount technology (SMT) screen plate

Abstract

The invention belongs to the technical field of measurement tools, and in particular relates to a contact measuring head for measuring the thickness of a surface mount technology (SMT) screen plate. The probe comprises a shell, an air guide rail, a probe, a connecting piece, a high-resolution laser ruler, a displacement sensor, a gas pipe joint and a data cable; the measuring head adopts a contact measurement principle, namely a probe ball at the end of the probe which is perpendicular to the SMT screen plate is in contact with the surface of the SMT screen plate, and the probe has a unique vertical movement freedom degree, namely the probe can only move vertically; the own weight of the probe is counteracted by a precise spring in the probe; the other end of the probe is connected with the high-resolution laser ruler which is arranged in parallel to the vertical direction of the probe; and the displacement change of the probe in the vertical direction can be detected in real time by a small laser displacement sensor in the probe.

Description

technical field [0001] The invention belongs to the technical field of measuring tools, and in particular relates to a contact measuring head for measuring the thickness of an SMT stencil. Background technique [0002] In the SMT processing process, the measurement of the incoming stencil becomes a key process to ensure the quality of SMT subsequent processing. The thickness of SMT incoming stencil is generally below 0.3mm, and the format is usually above 300mm×300mm. This kind of stencil has the characteristics of thin material, high precision, large format, high flexibility, and many types of materials. As the market's requirements for the processing efficiency and cost of SMT stencils are gradually increasing, the format of SMT stencils is getting larger and larger. For the supporting professional measuring equipment, it is required to reduce the cost of the equipment itself as much as possible under the premise of ensuring sufficient measurement accuracy. SMT incoming s...

AI Technical Summary

Problems solved by technology

[0004] 1. The surface of SMT stencil raw materials is often not clean, and some dust exists irregularly. If a laser displacement sensor is used to measure it at this time, these dusts will affect the direction of laser beam emission, thereby affecting the stability of measurement accuracy;

[0005] 2. The ambient light of the measuring equipment will affect the surface brightness of the material at the measuring point, thus indirectly affecting the measurement accuracy

The surface properties of the material are diverse, and the microstructure is similar to a "wrinkled" surface. The size of this microstructure is often in the range of 10um or even smaller, but it is enough to have a great impact on the reflection angle of the laser beam, which directly leads to a decrease in measurement accuracy. , it is difficult to meet the high-precision measurement requirements of SMT stencil thickness

[0007] 4. Laser displacement sensors are mostly precision components, especially high-precision laser displacement sensors are almost all dependent on imports, which are expensive

[0008] Due to the influence of the above problems, it is difficult to control the thickness measurement accuracy of SMT stencils within 1um, and generally it can only be stabilized at 5um or even larger. Otherwise, the overall surface of some stencils is relatively smooth, and the measurement accuracy may be better, but the overall measurement Accuracy and stability can not meet the requirements of SMT stencil thickness measurement accuracy 1um

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