Principles and methods for quality assessment of solder joints

- Oct 11, 2018-

Generally, the quality assessment shall be carried out according to the appearance quality status of the inspection solder joints.

Principle 1· full inspection principle: visual or instrumental inspection shall be adopted, and the inspection rate shall be 100%.

2, the principle of non-destructive: in addition to spot inspection of solder joints, do not recommend the use of easy to damage solder joint inspection and evaluation method.

Method

1, visual inspection Visual inspection is simple and intuitive, is the main method to verify the appearance quality of solder joints. The quality of the solder joints is visually inspected by means of a magnifying glass with or without illumination with a magnification of 2-5 times. If controversial, a magnifying glass of 10 times or more magnification can be used.

2, visual and hand test by hand or other tools on the solder joints at a suitable force or speed, relying on the visual and hand feelings, comprehensive judgment of the quality of the solder joints.

3. Online testing Online testing is an indirect method for assessing the quality of solder joints. During the assembly process, each component on the board is electrically tested. The test signal is applied to the combined node, and the output response value is measured to determine whether the solder joint between the component and the board is present. defect.

4. Other tests may be carried out by destructive sampling, such as metallographic analysis. If conditions permit, X-ray, three-dimensional imaging, and laser infrared thermal imaging may also be used for testing.


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