PCB News - How to avoid excessive solder paste consumption

How to avoid excessive solder paste consumption for through-hole reflow soldering?
Through-hole reflow soldering is a soldering process in which through-hole plug-in components use a reflow soldering process in the PCB assembly process. The biggest advantage of through-hole reflow soldering is to save cost and investment. Then, in the through-hole reflow soldering process, a common The problem is that the consumption of solder paste is very large, how to avoid it?

PCB board

1. One printing: local thickening template

In one printing of the smt process, when the local thickening template parameter a=0.15 mm, b=0.35 mm, it can meet the requirements of the smt process for the amount of solder paste. The local thickening template can be selected for one printing, rubber squeegee, hand-printed solder paste, etc., to reduce the amount of solder paste used. But this method is only suitable for some circuit boards with small lead density and large lead diameter.

PCB board

Second, the second printing

For some hybrid circuit boards with high lead density and very small lead diameter, even if the local thickening template is used for one printing, the amount of solder paste used cannot be met, it is better to use the second printing solder paste. The technical steps of secondary printing and soldering are as follows: After the components are mounted on the surface of the solder paste, the first-level template (with a thickness of 0.15 mm) is used for printing; after the solder paste through-hole inserts the components, the second-level template (with a thickness of 0.3-0.4mm) print it once.

Three, matters needing attention

In the smt process, although consumables such as the consumption of solder paste are more important, don’t blindly control the use of important materials and use excessively "harsh" materials, otherwise the strength of the solder joints will be unqualified, and the result will be lost. .

In the SMT process, when the through-hole is put into the part, the material consumption of through-hole reflow soldering/the quality of the material used for wave soldering=80%, it means that the solder joint strength of through-hole reflow soldering meets the standard . If the former consumes less than 80% of the latter's consumables, the strength of the solder joints will not meet the standard.

SMT patch

In summary, no matter what kind of circuit board it is in, whether it is primary printing technology or secondary printing technology, do not blindly use through-holes for the production and processing of through-holes into PCB components in order to meet the use of solder paste. The consumption of materials used in reflow soldering/the quality of consumption of materials used in wave soldering is less than 80% of the critical value, and should be greater than the critical value every time.

In the traditional printing process, the commonly used soldering methods include surface soldering and the through-hole reflow solder joints we call today. The latter consumes a lot more solder paste than the former, so in most smt processes, solder paste is solved. Consumption has become the primary problem. The above-mentioned technology can be used to meet the demand for solder paste in the smt process under the premise of ensuring the quality of the solder joints.