IPC-A-610E Broadens Scope

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Streamlined IPC-A-610E is supplemented with flex circuits, board in board and package on package (PoP).

Rapid advances in semiconductors are increasing the complexity of assembled boards, escalating the difficulty for inspectors who determine whether assemblies meet desired quality levels. This complexity comes as business changes put more pressure on inspectors to provide higher quality without adding time to the examination process.

IPC performed a major revision of IPC-A-610, Acceptability of Electronic Assemblies, in response to the industry's needs. The E revision of IPC's most widely used standard, which provides visual acceptance criteria for post-assembly mechanical and soldering assembly requirements, now addresses additional technologies, including flexible circuits, board in board, package on package, depanelization, and additional SMT terminations.

In addition, the standard has been revamped for ease of use and clarity. Sections have been reorganized so that data and images are easier to find and information easier to use.

The photos and drawings that show good and bad connections — deemed one of the most important features of IPC-A-610 since it was released in 1983 — have also been upgraded. There are 165 new or updated illustrations, bringing the total to more than 800. These images will help inspectors quickly determine whether the assembly they're examining should pass or fail.

"The improved organization and categorization of IPC-A-610E has made the document more concise and user friendly, current with industry advancements and technology," said Zenaida Valianu, training and development specialist at Celestica. "The document is more intuitive and manageable than before, allowing users to navigate more easily and locate information promptly, which will also reduce the amount of time spent on interpretation.

For example, inspectors who have boards with potentially damaged parts can now turn directly to the section on damaged components. In the past, all data, including damage associated with a component termination style, was located in a section on those part types, forcing users to flip between sections.

Minor yet powerful wording changes have been made in the E revision to eliminate some of the uncertainties that have plagued inspectors in the past. "The use of the emphasis implied by 'shall' informs the reader that the requirement is mandatory," said Vicky Freeman, engineering technician at Flextronics. "The upgraded standard's format will allow our employees to easily comprehend the requirements of the job they are performing."

The many changes that have occurred in array packaging since the standard's last revision are also addressed. As array usage expands, BGAs, flip chips, and similar technologies are evolving quickly.

"We're providing criteria for non-collapsible balls on area arrays. Previously, we only looked at tin/lead balls that collapsed during reflow," said Jack Crawford, IPC director of certification and assembly technology. "Lead-free solder balls don't collapse and have different wetting characteristics. That means there can be more process-related problems during manufacturing."

Changes related to through-hole lead-free processes, such as hot tear and fillet lifting, are also updated in the latest iteration of IPC-A-610. Hot tear most commonly occurs when the copper in solder alloys doesn't disperse evenly, prompting the copper-rich areas to separate. However, this doesn't mean it is a defect. Similarly, the document details the appearance of fillet lifting. This anomaly appears when the solder fillet is lifted from the land, but it is not a defect.

One of the new areas covered by the upgraded document is depanelization, which Crawford calls a "high interest area." He adds, "We're covering it now, looking at edge routing, edge delamination, and other issues. There are pictures that show various defects, things like cutting too close to the edge and damaged conductors."

The growing number of companies using flexible circuits will also find sections that detail common issues, such as flex-to-flex interconnections.

For designers and manufacturers trying to jam more components into smaller spaces, criteria for PoP technologies, often used to boost memory capacity in large data processing and telecommunication systems, are now included.

For board-in-board connections, daughter boards can be mounted perpendicular to the assembly using a through-the-board method. IPC-A-610E now provides solder acceptance criteria. The enhanced text and additional photos should benefit trainers and new personnel almost as much as it helps inspectors on production lines.

Some trainers note that the most important change in the standard is that it is better synchronized with existing training approaches. "Restructuring the IPC standard sections to follow a proven IPC training flow will help communicate information more readily," said Valianu, who also serves as a Master IPC Trainer at Celestica. Another Master IPC Trainer, Freeman, agrees, "The new format allows enhanced reference to related areas that improves training and minimizes discrepancies in associated areas of fabrication."

Upgrades to a companion document, J-STD-001E, Requirements for Soldered Electrical and Electronic Assemblies, have also been made. IPC J-STD-001E provides material and process requirements for producing soldered electrical and electronic assemblies, aiding those who set up manufacturing processes. Additional pages and 14 new photos help these specialists move into production quickly.  SMT

Terry Costlow, IPC online editor. IPC-A-610E, Acceptability of Electronic Assemblies, is available at www.ipc.org/610E. Translations of the revised standard in multiple languages will be released in the coming months.

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