Essential Chem Etching Considerations: Hole Size & Metal Thickness

Part 1 of 3

While photo chemical etching provides exceptional precision, designers should consider several variables to ensure their design uses the process efficiently.

Let’s start with metal thickness. It has complex relationships with three key design elements:

  1. Hole size
  2. Line widths
  3. Bevels

Through the next three blog posts, we’ll discuss each design element and its relation to metal thickness. With this knowledge, engineers can design parts that are optimized for the process.

Metal Thickness and Hole Size

A general rule of thumb: the diameter of a hole cannot be less than the metal thickness.

While this is a good general rule, it’s not entirely accurate.

The relationship between hole size and metal thickness does vary as the thickness changes, but a more exact relationship would look more like this:

METAL THICKNESS (t) SMALLEST HOLE DIAMETER (D)
Less than .001" Must be determined by test run
.001" - .005" At least metal thickness, with a .003" minimum holesize
.005" or over At least 110% metal thickness

Conclusion

You should always keep this relationship in mind when designing for photo chemical etching. A familiarity with the relationship will help ensure you produce the optimal product from your photo etching process.

Next week, we’ll jump into the relationship between line width and metal thickness.

Advanced photo etching tips design engineers should know.