Photo etching Design Guide
VACCO's Photo Etching Design Guide was generated for those new to the photo etching process. We hope this will serve as a reference and raise awareness of our etching capabilities. We encourage you to utilize these tools and information when developing your next prototype. If you have any questions and would prefer to speak to a VACCO Representative please feel free to contact our Sales Team, We would be happy to assist you.
Advantages of Photo Chemical Etching
As complex or challenging as your design may seem, our photo chemical etching process makes producing intricate parts simple. Photo Chemical Etching is a fast and relatively inexpensive way to produce a wide variety of metal parts, with continuous accuracy every time. Our consistency lies within our tooling capabilities. Our photo tools are computer generated which increase accuracy while reducing tooling costs, in comparison to hard tooling.
How it Works
1. VACCO takes your drawing or sketch reflecting the exact specifications of your part or design needs. If you don't have a drawing, no worries, refer to this page or simply call our Sales Team to help turn your idea into a realization.
2. Once the drawing and its specifications have been established, VACCO will proceed with producing an AutoCad Photo Tool to transfer your exact needs into further production of your photo etched parts.
3. Using the Photo Tool, VACCO can now transfer the part/image(s) onto a clean metal sheet from the material you have specified. (Please be sure to reference the many different material types VACCO can etch.) Before imaging, the metal sheet will first be laminated with UV sensitive film often referred to as photo resist.
4. Using the photo tool and the photo resist laminated metal, the metal sheet can then be exposed to a UV light source that transfers our exact requirments onto the laminated sheet of material.
5. After exposure and before etching, the exposed laminated sheet must be developed allowing the unwanted soft photo resist material to be removed and the required hardened photo resist to remain thus creating the pattern we all desire to produce your etched parts.
6. Taking the developed sheet of metal VACCO can now chemically etch away the defined pattern of metal from the metal sheet, leaving you the required photo etched parts you desire.
7. After the etching process is performed VACCO simply washes away the photo resist and performs final inspection and packaging procedures before the parts are shipped to you in a safe and economical manner.
Dimensions & Tolerances
There are no specific rules regarding etching tolerances, but there are some common variables which can have an impact on etching tolerances. Consider the following when developing your next prototype: the kind of metal, the thickness of the material, the size of the parts' features, the size of the part, the process sheet size, and the number of critical dimensions per your part.
Generally speaking, etched dimensional tolerances are +/- 10% of whatever the metal thickness is. If a part is made of .010" thick stainless steel, then the general rule would be that dimensional tolerance of the parts' features would be +/- .001" ( or 10% of the material thickness.)
For more information and futher discussion please don't hesitate to call anyone of the VACCO Sales Team.
Hole Size/ Slot Width to Metal Thickness
Typically, the diameter of a hole or slot width can't be less than 1.1 times the material thickness. However, the relationship varies when metal thicknesses change. Below is a chart that might give a better idea of the relationship between the hole size to metal thickness.
- Metal Thickness (t)
- Smallest Hole Diameter (d)
- Less than .001"
- TBD by test run
- .001" - .006"
- At least Metal Thickness
- .006" or Over
- At least 110% Metal Thickness
Line Width to Metal Thickness
Spacing between holes and slots become a design factor when a part contains a large number of holes and/or slots. The metal between the holes is referred to as Bar Width. There are limitations as to how small the bar width between holes can be. In metals less than .005" thick, bar widths must be at least equal to the metal thickness.
Inside & Outside Corner Radius to Metal Thickness
The smallest corner radius is proportional to the metal thickness. However, there are circumstances where the radius can be smaller, depending on your requirements.
Outside corners etch sharper than inside, so radii less than material thickness are easily obtainable.
If etching variance is a requirement on your product, please specify the percentages needed.
Tabs or Tie-Ins
Tabbing is performed by connecting one or more lines of metal from the part to the process sheet border or tie bars to keep parts in place. These tie-ins are made as few and as small as possible keeping consistent with the size of the parts being etched. Tabs are beneficial for parts with tighter tolerances, and those undergoing plating operations, not to mention they are cost efficient and will help produce a higher yield of quality product. Two common variations of tabbing most widely used include:
External Tab - These have a break off point, which leaves a small "burr" attached to the part.
Recessed Tab - Like external tabs, recessed tabs have a breaking point, only it becomes recessed into the actual part. We recommend this application if your product specifications require tabbing, but cannot have extended areas beyond its perimeter.
If your outside requirments are crucial or you prefer to avoid tabbing all together, you may want to consider drop outs. These are tab free parts, meaning the part does not remain in the sheet during the etching process. This method is recommended for metals with a thickness of .010" or thicker. Be advised, a drop out is less consistent, has looser tolerances and therefore is more expensive to handle, inspect and package in comparison to a tabbed part.
- Blue Tempered Spring Steel
- Brass, Alloy 230, Red
- Brass, Alloy 240
- Brass, Alloy 260, Cartridge
- Brass, Alloy 268, Yellow
- Carbon Steel, C1008,C1010
- Copper, ETP C110
- Copper, Olin 194
- Copper, OFE, OF C101, C102
- Cupro Nickel (CuNi70/30) Alloy 715
- Beryllium Copper Alloy 25, C172
- Beryllium Nickel Alloy 360
- Haynes 25
- Haynes 214
- Hastelloy 276
- Hastelloy B-2
- Hastelloy X
- HyMu 80, Hypernom
- Inconel, Alloy 600/625
- Inconel, Alloy 718/X-750
- Jeweler's Bronze, Alloy 226
- Nickel, Alloy 42, 49
- Nickel, Alloy 200/201
- Nickel, Silver, Alloy 752, 770
- Nitronic 60
- Phosphor Bronze, Alloy 510
- Stainless Steel, 300 Series
- Stainless Steel, 400 Series
- Stainless Steel, 17-7PH Series
- Stainless Steel, AM-350
- Titanium, CP Grades 1-4
- Titanium, Alloy 3AL-2.5V
- Titanium, Alloy 6AL-4V
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