Johnathan; When brazing copper, or one or more of the alloys of copper & other metals together there is a fine line between a good stable connection and a poor one. Consideration of how the finished product is going to be used is the primary factor. For instance will the joint be subjected to stresses of movement, extreme temperatures, pressures, vibrations, tension, torsion, compression, ETC.
Or a combination of these factors, and when the possibility of dissimilar metals will be joined the fillers & flux must be selected according to application.
One huge mistake many people make whether they are novices or very experienced is too little or too much heat. The next biggest mistake particularly when flame brazing or welding is they get their flame too oxygen rich, this can burn the metals and or create oxides in the joint itself. in the case of copper to other alloys the contaminant is called phosphides created by the phosphorus in the alloys.
Set the flame on your torch so you can see a slightly cooler blue feather. it is also best if you have your regulators set to very low pressure just a little higher than needed to produce the desired flame size this gives you better fine adjustment control over your flame
Hope this helps in someway