| sethnintendo said: Just going back to your statement about lead free solder. You are right that lead free solder was pretty bad to work with back in the early / mid 2000s. To my knowledge they have been tweaking with lead free solder for awhile considering that it doesn't flow as well and takes more heat than lead solder. Lead free solder was a pain in the ass is the only thing I can remember back when I used to solder (mainly just solder with lead). Now, I am just an ICT tech (basic tests on components of boards that were just built) but we still run into problems sometimes when doing lead free boards. It seems that they are more failures / problems when the line is producing lead free boards (not always case but for certain server boards). |
I think one of the biggest issues is the melting point as you alluded to personally. With "lead" solder the melting point is around 180 degrees Celsius where as "lead free" it's close to 230 degrees Celsius. As you get to 230 degrees Celsius you are at risk of damaging the silicon of the BGA chip so you cannot risk applying the heat for as long to the board and you will likely be taking the temperature up to that point and down quicker which is all bad for creating a solid solder joint. In the case of "lead" solder the temperature is safer for the silicon inside the chip so you can be slower and less aggressive in your heating profile which makes it a lot easier to get strong joints. People say "lead"solder flows better but in my opinion a good quality lead free solder flows just as well when the joint is heated correctly, it's just a lot harder to apply the extra heat without damaging the board and components (It's a lot easier to lift pads now than ever before).
Like you say, even now they still haven't resolved all the issues with the move to lead free solder and I think it's responsible for the unreliability of so many modern electronic appliances now. I guess there is no replacing the decades of experience and knowledge acquired with using "lead" solder so it was always going to be a slow process to perfect working with a new product.
