When I first started out in the middle 1980's (or was it the early 1980's?????) doing NTRAK modules, I soldered everything. My father, who was an electrical engineer working for GE and Douglas United Nuclear on the Hanford Atomic Reservation in Washington State, taught me early on how to solder, so soldering my model railroad connections wasn't a big deal.
However, since (obviously) NTRAK modules are portable, I found after a few years that many of my solder joints were coming apart during transportation to and from setups. It was easy enough to tip my 6' modules up on their sides and re-solder the joints as well as inspect existing joints to determine if they looked like they were going to fail, and re-solder them.
But, after a few years of setups and transporting my modules in the back of my Suburban to various destinations, it was beginning to be a PITA to count on at least one or two failed solder joints every setup.
Soooo, when I finally decided to go with DCC, I also decided to completely rip out my old rat's nest of DC wiring since my new DCC wiring would be much less complicated.
Although it is inevitable that some solder joints were going to be necessary, I decided that the vast majority of wire-to-wire joints were going to be joined by using Genuine Scotchlok IDC's making sure to use the correctly sized ones suitable for my wiring.
For the joints that needed to be soldered, I decided to use 96/4 Tin/Silver solid core solder because it is 5 to 6 times stronger than "normal" Tin/Lead electrical solders. I used soldered joints only on my toggle switches I used to actuate my Tortoise switch-motors (which also have soldered wiring) AND for my 6" long solid-copper track feeders soldered to the bottoms of my Code55 and Code40 trackage...soldered to each and every piece of rail (not relying on flimsy rail joiners for electrical continuity).
In the years since I installed my new DCC wiring, I have not had a single failure at a joint completed using a Genuing Scotchlok IDC...which is much much different than my previous experience with soldered wire joints.
So, I highly recommend using the Genuine Scotchlok IDC's for model railroad wiring, as I have been convinced they are more reliable than soldered joints.
Photo (1) - Nearly complete new DCC wiring under one of my 6' long modules/sections that make up my portable home layout with MANY IDC's being used:
Likewise, I always thought "belt and suspenders!" as I happily crimped and then soldered numerous Molex connectors and feeder wires on Modutrak.
It took a couple courses in race car wiring to set me straight. For portable layouts, and especially ones that bounce around in trailers across the country... the solder joint, no matter how strong, adds a stress point in the wire that can bend and snap.
So now I'm almost 100% crimp. I utilize a lot of barrel connectors to join wires to buses too. With two layer adhesive heat shrink around the connection. I solder only to rails and to tortoise pads.
