Ive used many of these and never had an issue.
https://www.ebay.com/itm/Aluminum-Heat-Sink-for-Solid-State-Relay-SSR-Small-Type-Heat-Dissipation-10A-40A/112200581898?hash=item1a1fad030a:g:vP4AAOSwAHBaQyZZ
Realistically a lot of the professionally designed machinery I work on does not use a...