To all that have inquired about 30 m gold thickness: This question would be better answered with a required application. Let me try to cover most of this subject and apply various applications. Many years ago (too many to mention), I performed an experiment to find out how many insertions I could get from a gold plated board into a connector. Carefully selecting the same thickness boards (. 062") I found the approximate following results, always with 100 M base nickel. 100m gold = 500 insertions; 50 m gold = 300 insertions; 30 m gold 50 to 75 insertions; 20 m gold 10 insertions. As you can see, the insertion count reduces rapidly as the gold thickness reduces. Now let's look at cost! Though gold is expensive, the labor cost to prepare the board for plating is much greater. For instance, let's look at the actual gold cost for these above thicknesses. Remember, the cost of labor to prepare the board for plating is the same for all thicknesses. Obviously, you don't need 100m of gold. Therefore, we will start with 50m. To reduce a typical set of 6" long fingers from 50m to 30 m will save you about 30 cents at today's gold prices. To reduce it from 30m to 20m will only save about 10 cents. On an expensive multilayer board, is this small savings worth potential quality problems. By the way this gold always should be a hard gold (99.96%-99.97% pure) with a knoop hardness range of 130 to 200 (optimum 170). When using gold for a surface finish that will be soldered you would like to use a soft gold (99.99% pure) and a knoop hardness of 70 to 130 and an optimum of 90. The thickness here should should range between 5 and 15. Closer to 5 than 15. This process makes electroless (or immersion) gold more desirable than electrolytic. The nickel thick should be maintained to a minimum of 50m. Wire bonding: Always a minimum of 50m nickel. For gold wire bonding the gold thickness wants to be a minimum of 50m and a purity of 99. 99% (no thalium). Purity is very important for any type of wire bonding process. For aluminum wedge wire bonding the same type of gold will be used. However, for aluminum wedge wiring bonding the nickel becomes critical. No contaminates and it wants to be plated a soft as possible. Requires good control of Ph and plating chemicals in the plating bath. When specifying gold thickness, you must ask how much you will save with a lessor thickness and who will benefit from the savings, you or your vendor. After nowing the cost for preparing the board for gold, it is a very simple task to calculate gold thickness variations. Contact a gold supplier for the amount of gold, and cost, per square inch per micro inch. Norm Einarson Printed Circuit Technology When using g