When submit your Gerber files for PCB fabrication, one of the fab notes you must be mentioned is the Solder Mask and whether to print a shiny solder mask, also called a glossy finish, or to a matte finish on your circuit board. Usually, most designers don’t specify their glossy or matte preference and leave the decision up to the PCB fabricator. Most fabricators will typically choose a glossy finish by default, the more popular of the two.

 

Glossy vs. Matte Finish

 

Glossy Solder Mask: A glossy finish for a PCB is a light-reflective solder mask lighter in color than a matte PCB finish. It has a poreless appearance as opposed to the softer look of a matt finish.

Matte Solder Mask: Matte finishes for PCB solder masks have no shine and tend to appear darker than glossy finishes. They have soft, porous appearance that does not reflect light.

 

There are no different requirements between the two solder mask finish types when discussing solder mask standards. Information on their use is contained in the latest IPC-SM-840E Qualification and Performance of Permanent Solder Mask. The specification is intended to the evaluation of liquid and dry film solder mask material and for the determination of the acceptability of use on a standard printed board system, and to enable the designer, fabricator, and user to collectively qualify a circuit board fabrication process. No matter glossy or matte solder mask, it will not affect board function in any way.

 

Benefits of a Glossy Finish

 

Many of the benefits of a solder mask finish depend on the designer’s aesthetic preferences. You might choose a glossy finish over a matte solder mask on your printed circuit boards due to:

 

  • Aesthetic Value: because PCB fabricators likely default to glossy finish choice for solder mask, many designers consider them the classic PCB appearance. Their shine gives them what perceive as a more modern look.
  • Appearance of Wear: The reflective properties of a glossy finish tend to make signs of wear look less prominent.
  • Scratch Resistance: Because of glossy finish’s harder surface, a gloss finish has higher scratch resistance than a matte finish in board fabrication and PCB assembly manufacturing.

 

Benefits of a Matte Finish

 

Your preference in PCB appearance will also determine whether you’ll want a matte finish instead of a glossy solder mask. A matte finish may make some aspects of fabrication easier. However, an experienced PCB fabricator will provide quality results regardless of solder mask finish. The benefits of a matte finish include:

 

  • Visibility during Inspection: A matte finish does not have shine under any lighting used during inspection. As a result, you can move easily see the appearance details of the boards and board assemblies.
  • Problem Detection: Matte finishes make problems more evident than glossy finishes. During inspection, it becomes easier to detect issues on a matte finish due to increased visibility.
  • Solder Ball Reduction: Research suggests that matte finishes reduce a board’s risk of solder ball information. Data indicates that a lower glossy level on PCBs results in lower solder ball levels.

 

Reasons to Choose a Glossy Finish but Not a Matte Finish?

 

The main difference between a glossy finish and a matte finish is an aesthetic one, and many people feel that a glossy finish simply looks better. Glossy solder masks are shiny. They reflect light and look lighter, while matte finishes are dull and dark. Glossy solder mask has a harden shell finish while a matte finish is softer looking.

 

Matte finishes may also scratch more easily and show residue or surface cosmetics better, although scratches on a gloss finish will show more. If you expect the look of your PCB will have a positive effect on your PCB assembly manufacturers or anyone who may end up looking at them, you may want to print with glossy finish. Just keep in mind the high light reflectivity can be nuisance to vision during assembly in some cases.

 

As a PCB designer or buyer, you may want to choose a glossy finish over a matter finish when:

 

  • Appearance Matters for Your PCB: In applications where appearance impacts your product marketing, a glossy finish can help by increasing aesthetic appeal.
  • You have No Specific Preference: If you don’t have a particular finish preference, remember that glossy finishes serve as the industry default for most PCB suppliers.

 

Why Choose a Matte Finish but Not a Glossy Finish?

 

Although it is no more cost-effective or efficient to choose a matte finish over a glossy one, there is one consideration that may cause some to prefer the matte finish, and it involves Tin Solder Balls. If you are concerned that solder balls may be a problem for you, you may be inclined to choose a matte finish. This is because, while there are several factors that contribute to solder balls, one is the level of surface roughness. The smoother the surface, the more likely it is that solder will ball up.

 

The theory behind this is that molten solder behaves differently on rough surface and smooth surfaces. On rough surfaces, it tends to form a convex shape, reducing the area solder balls can attach to, while on smooth, hard shell of the glossy finish, many PCB experts feel that a matte finish will result in fewer solder balls. With all of this said, glossy finishes are used all the time on boards, so you may not find this to be a particular problem.

 

When you’re considering your choice of solder mask finish, you might prefer a matte option in these situations:

 

  • You want to streamline production as much as possible: When you consider production accuracy a top priority, a matte finish may give you more peace of mind during board fabrication. However, skilled PCB fabricators should detect errors in either finish type.
  • Participation in quality assurance matters to you: If you plan to inspect your PCB yourself after PCB production, a matte finish can help with the process. It shows errors more clearly for you to provide accurate feedback to your PCB fabricator.

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