IPC Classes: Similarities and Differences

Whether just breaking into the advanced printed circuit board industry, or a veteran of rigid, rigid-flex, and flex PCBs who has just been going with the flow, IPC quality Classes for the manufacturing of PCBs might seem foggy. It is obvious that Class 3 is more advanced and therefore more costly than Class 2 but why? What are the major differences that define Class 1, Class 2, and Class 3? Callouts for Classes 1, 2, and 3 can be found in IPC-6011. The IPC-6010 series (IPC-6011 Generic, IPC-6012 Rigid, IPC-6013 Flex, IPC-6015 MCM-L, IPC-6017 Embedded and IPC-6018 High Frequency). Now for the two newest and most rigorous qualification and performance specification for Rigid Printed Board shop: IPC-6012DS “Space and Military Avionics Applications”, and IPC-6012DA “Automotive Applications”. Both are addendum to IPC-6012D. Then of course there is the IPC-A-600 Acceptability of Printed Boards. IPC-A-600 has visual illustrations that portray specific criteria of the requirements of the current IPC-6010 series.

  • Class 1: Class 1 boards are in the “Limited Life” category or electronics that are of lower reliability expectance. They are considered general electronic products. A flashlight would be an example of this.
  • Class 2: In Class 2 Printed Circuit Boards, reliability is expected but not critical. Better thought of as dedicated service electronic end products. For example, the motherboard of a laptop.
  • Class 3: Class 3 boards require absolute reliability because their applications, which usually include military or medical. Examples would be a pacemaker, an airplane component or radar equipment for instance.
  • IPC-6012DS “Space and Military Avionics Applications Addendum” to IPC-6012D “Qualification and Performance Specification for Rigid Printed Boards”. Class 3 requirements shall apply where criteria is not addressed in the IPC-6012DS.
  • IPC-602DA “Automotive Applications Addendum” to IPC-6012D Qualification and Performance Specification for Rigid Printed Boards”. Class 3 requirements shall apply where criteria is not addressed in the IPC-6012DA.

Among many things, these classes define the degree of inspection and the level of acceptance that one inspects. Let’s take the example of annular ring. Obviously, the goal in any project is a perfect, even “bullseye” of the hole to the annular ring. A perfect manufactured via has an annular ring that is even on all sides with no breakouts at all, but like life, not all moments are perfect. “There are instances where vias are manufactured outside of desired parameters.” The amount of acceptance of these vias is determined by the class of the PCB. In terms of Class 2, a breakout of 90 degrees is acceptable. Class 3 printed circuit board will call for a via to be closer to the “bullseye” with a .001969” measured annular ring on all sides. A military spec MIL-PRF-55110 or MIL-PRF-31032 PCB requires a .002” measurement on all sides of the annular ring. In conclusion, a Printed Circuit Board will be manufactured the same no matter what, but inspection is what truly defines a board’s class and Streamline quality.

Streamline Circuits is a leading manufacturer of high quality Printed Circuit Boards offering Rigid, Rigid-Flex and Multilayer Flex. We are committed to providing our customers the most advanced technology, quality and engineering support available. Streamline’s customers take advantage of these highly valued resources to develop a cost effective product in a time sensitive manner. These capabilities are critical for today’s technology driven customers. Streamline Services: communications, military & aerospace, industrial electronics, instrumentation and medical equipment markets, who need to get their quality products to market first.