Hi excellon1, we are loving this discussion. Thanks for all your inputs! You make a good point about the area of the copper. Yes the through-hole pin may not need thermal reliefs for this connection to the copper plane if this is the only copper layer connected. As in the case of through-holes, thermal reliefs are used to prevent heating escaping from the hole during soldering. This enables the local region to heat sufficiently such that an inter-metallic bond can be established between the solder and the metal surface of the inner hole. It should be noted that in this case, the heat source is the solder! However, for surface mount production, the solder is not fluid and so the heat energy is provided from the atmosphere, not the solder. Therefore surface mount pads use thermal reliefs for a different reason. Back to the topic of through-hole pins: In the first image, there are still some things that we cannot know. For example - how thick is this copper? Secondly, is this copper plane on the topside or the soldering side? (We shall assume this must be an outer layer due to the surface component nearby. However, embedded layer pads area possible using Allegro PCB Editor - but let's assume not in this case....) Do you have any thoughts if these factors should affect your decision about removing thermal reliefs? Also, do you know any other pin technology which could be used to avoid this entire dilemma?
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