Specific Process Knowledge/Etch/KOH Etch/ProcessInfo: Difference between revisions

@@ Line 59: / Line 59: @@
 ==Mixing KOH==
+Danchips standard solution in the KOH baths has a concentration of 28 wt% and is mixed of either 500 g KOH pills to 1 l of water or 1liter of a premade 50wt% KOH solution to 1.2 l of water.
+If you want to make your own mixture of KOH in a beaker in Fumehood 6 you can either do this by using KOH pills or a premade mixture of 50wt%. Using the pills the mixture will spontaneously heat up when mixing which is not the case when using the premade mixture.
+If you want to make solution using the KOH pills you must remember that the pills are only 85% pure.
+For 1 l of water you can calculate the required amount of KOH pills (X) to achieve the desired concentration in wt% (Y) by:
+(0.85 ∙X)/(X+1000g)=Y
+X=(Y∙1000g)/(0.85-Y)
+So for a 10wt% solution you will need 133 g pills for each liter of water.
+If you use the 50wt% premade solution you can calculate the amount of solution X you need to add 1 liter of water to achieve a concentration of Y wt% by:
+(0.5∙1.509 g/ml ∙X)/(X∙1,509 g/ml+1000g)=Y
+X=(Y∙1000g)/(1,509 g/ml∙(0.5-Y))
+where 1.509 g/ml is the density of a 50wt% solution KOH at 20 °C.
+So for a 10 wt% solution you will need 165 ml of KOH to 1 l of water.
 ==Theory==