Size matters. That statement rings true for many things in life. A larger vehicle can transport more people, but you may have trouble finding appropriate parking. A person with smaller hands can easily retrieve lost change from the couch cushions, but may have trouble gripping a barbell at the gym. Personally, I like a large cup of coffee in the morning; my bladder on the other hand, usually isn’t happy with that decision. In today’s world with electronics continuing to get smaller and smaller, the size of the solder powder used in a solder paste matters, too. The size of the solder powder affects the solder paste performance, and the traditional Type 3 powder size might be too large for the application at hand.
The main reason smaller solder powders are used is to improve the printability/dispensability of the solder paste. Solder powder types can range from Type 3 (the largest) down to Type 7 (the smallest). As solder powder size decreases, the solder paste can be printed through smaller stencils or dispensed through smaller syringes. You might be thinking, “Great! If that’s the case, set me up with a Type 7, that way my room for error is much lower.” Well, not only can that cost more money, there are other performance changes that occur when smaller solder powders are used. With smaller powder sizes, shelf life is generally shortened, there is higher potential for random solder balling and graping, and voiding behavior can also affected. So this is where you need to find your 'Goldilocks' powder size. Not too big and not too small, but just right.
It’s crucial to understand the differences in performance that may be seen with smaller solder powder sizes during electronics assembly. Indium Corporation has already been looking ahead to the future needs of the electronics industry and with smaller solder powder sizes becoming increasingly common, we are formulating products with those needs in mind. Here you can find information on choosing solder powder size for dispensing and printing, and also dispensing die-attach solder paste. If you have any questions, or for more information on AuSn solder paste, please email me at jgallery@indium.com. For all other paste inquiries, contact Claire Hotvedt at chotvedt@indium.com.