How to Design Your PCBs for the IPC-6012DA Automotive Standard

In 1769, a French Army Captain, Nicolas-Joseph Cugnot, built the first self-propelled or automotive vehicle. Like many technological advances, his invention had a short-sighted military objective: to carry cannons, which was formerly done by horse-drawn vehicles. Fortunately, this humble start led to the assembly line and mass production of automobiles. The continued growth of the automobile industry has been made possible by the effective use of machines, which as Henry Ford said, “were devised not to do a man’s job, but to take the heavy labor from a man’s back and place it on the broad back of the machine.” Today, we have autonomous robots building automobiles, including electric and autonomous vehicles, EVs and AVs, respectively.

Unfortunately, advancements in roadway construction have not kept pace with the vehicles that traverse them. Streets and roads range from dirt and gravel to concrete and even steel. It is too common for roadways to contain potholes or be in disrepair. These conditions, along with the normal vibrations and high temperatures in which automotive electronics must operate, require that devices and PCBs be designed and manufactured to meet stricter requirements than other commercial systems. The standard that most explicitly addresses these concerns is IPC-6012DA, Automotive Applications Addendum to IPC-6012D Qualification and Performance Specification for Rigid Printed Boards.

Let’s take a look at this circuit board regulation that specifically focuses on PCBs for automotive applications. We will then be better able to specify a few tips to ensure your design is in compliance with its requirements.

What is the IPC-6012DA Standard?

Prior to defining IPC-6012DA, it is informative to discuss the base standard, IPC-6012, Qualification and Performance Specification for Rigid Printed Boards. Founded in 1957 as the Institute for Printed Circuits by six circuit board manufacturers, the organization has grown into a 4,000 plus member association of designers, manufacturers and users of PCBs. Recently adopting the name IPC - Association Connecting Electronics Industries, the association produces industry standards for the design, materials, manufacture and testing of PCBs. IPC-6012, which specifies quality standards for rigid PCBs, was originally published in July 1976. Although other documents deal specifically with an aspect of PCB quality, such as IPC-SM-840 for Solder Mask, IPC-6012 provides quality standards for various performance classes of boards. This standard has been revised several times, as shown below.

The IPC-6012 Standard Revisions

• IPC-6012A   Published October 1999

 Amendment 1 added July 2000

• IPC-6012B   Published August 2004

 Amendment 1 added February 2007

 Amendment 2 added March 2008

• IPC-6012C   Published April 2010
• IPC-6012D   Published September 2015

 Amendment 1 added October 2017

Why the IPC-6012DA Standard?

In most cases, the specifications and guidelines presented in IPC standards apply to circuit boards across virtually all industries. According to the standard, the IPC-6012DA addendum to IPC-6012D, which was published in May 2016, was developed to “ensure the reliability of printed boards that must survive the vibration and thermal cycling environments of electronic interconnects within the automotive industry.” The adoption of these standards provides developers with the confidence and assurance that their design and the manufacturing processes of their contract manufacturer (CM) will result in electronics and PCBs that can reliably operate in the unique and challenging automotive environment.

IPC-6012DA provides guidance and requirements that specifically target the following circuit board fabrication and PCB assembly steps:

IPC-6012DA IMPACT ON PCB FABRICATION AND ASSEMBLY
IPC-6012D Section	IPC-6012DA Description	Fabrication/Assembly Step(s)
3.3	Specifies inspection procedures for uncovering defects.	Visual/Automated Optical Inspection (AOI)
3.3.4	Specifies tolerances for lifted lands, pad and plated through hole (PTH) separation	Hole drilling, plating
3.4.1	Specifies tolerances for drill hole sizes	Hole drilling, plating
3.4.3	Specifies bow and flex limitation	Solder reflow
3.5	Specifies the quality of conductors and directs inspection method	PCB Stackup, AOI
3.5.4.2.1	Specifies land quality and tolerances for defects	Etching, visual/AOI
3.6.2.1	Specifies PTH quality	Hole drilling, soldering
3.7.3	Specifies solder mask thicknesses	Solder masking
3.9	Specifies cleanliness quality control measures	Fabrication and assembly quality control, finishing, Resistivity of Solvent Extract (ROSE) testing is required
3.9.1	Specifies board cleanliness prior to solder masking	Fabrication quality control, ionic testing is recommended
3.9.2	Directs that cleanliness testing be done after solder masking, soldering and finishing	Fabrication and assembly quality control, solder masking, soldering, finishing

Design Tips to Meet the IPC-6012DA Automotive Standard

The specifications and directives of IPC-6012DA are intended to ensure that PCBs used in automotive applications are able to withstand the unique vibratory and thermal stresses that are inherent in automotive environments. Following the tips below will help your design meet these compliance requirements.

IPC-6012DA Design Tips for Board Fabrication

 

• Ensure that your land and spacing specifications are within IPC-6012DA tolerances.

• Ensure that drill holes meet the size and quality requirements of IPC-6012DA and align with the aspect ratios of your CM’s equipment.

• Make sure solder mask specifications fall within IPC-6012DA tolerances.

• Ensure that your CM applies good quality control that includes visual and AOI inspections throughout the fabrication and assembly processes.

• Ensure that your CM prioritizes cleanliness and cleans boards after each process that may result in excess debris, including before and after solder masking.

• Apply Class 3 specifications for all board properties unless otherwise specified.

Adherence to the specifications of IPC-6012DA is required in order for your board’s to be used in automotive systems, including EVs and AVs. A great deal of the responsibility for compliance is placed on your PCB’s manufacturing process. Therefore, it is imperative that you select a CM that is capable of meeting these critical regulatory requirements. At Tempo Automation, we specialize in building boards that meet or exceed IPC Class 2 and 3 requirements faster than anyone in the industry. Moreover, we have the expertise to support you throughout the development process.