The operating instructions behind the cleanliness requirements in IPC J-STD-001G

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IPC-WP-019: The Instructions For Use Behind The Cleanliness Requirements In IPC J-STD-001G

IPC-WP-019, “An Overview on Global Change in Ionic Cleanliness Requirements”, was originally published in August 2017. This document, a white paper, was published to help the industry understand the new cleanliness requirements in the environment. IPC revision G J- STD-001 requirements for welded electrical and electronic assemblies.

Until that time, for many years, large facets of the industry used a requirement of 1.56 µg / cm2 NaCl to determine the acceptable cleanliness of printed circuit assemblies. This was carried out using the resistivity test of the solvent extract (ROSE) according to IPC-TM-650, method 2.3.25.

With the increasing complexity of assemblies and the evolution of the chemical composition of fluxes and cleaning solutions, the ROSE test, originally developed in the 1970s as a process control method for fluxes based on rosin, was not an adequate test for acceptable levels of ionic residues on the new flow chemistries. Many data sheets indicate that new flux chemistries cannot be dissolved with alcohol or water. The ROSE test is based on spraying / immersing the panel in a 75% alcohol / 25% deionized water solution. From this information, science tells us that the ROSE test is inadequate in these situations.

A different method or a combination of methods to establish the cleanliness of an assembly is necessary to provide “objective evidence”. This knowledge and understanding led a small group of dedicated volunteers who called themselves “The Rhino Team” to review the requirements of IPC J-STD-001 and make recommendations for change. This team included technical subject matter experts from aerospace, materials, automotive and commercial companies.

Over the course of several years and presentations to the IPC J-STD-001 working group, new cleanliness requirements began to emerge. The working group determined that a qualified manufacturing process was required for manufacturers of Class 2 and Class 3 products.

The working group quickly realized that the industry needed a technical explanation of the requirements and advice to facilitate implementation. The working group asked the Rhino team to develop a white paper before the requirements were incorporated into IPC J-STD-001. After two years of work, IPC-WP-019 was approved by consensus. Unlike a standard, IPC-WP-019 provides further explanation, clarification, knowledge and / or guidance on the subject of cleaning requirements with a view to incorporating these cleaning requirements into IPC J -STD-001.

IPC-WP-019 explains to the reader the cleanliness requirements of Chapter 8 of IPC J-STD-001G. Scenarios are provided to assist the reader with examples of how the requirements can be implemented, and additional references available for guidance.

Eleven months after the publication of the original IPC-WP-019, a revision of the white paper was released, aligned with the new cleanliness requirements which form the basis of amendment 1 of IPC J-STD-001G . Because of the importance of cleanliness in electronics assemblies, IPC J-STD-001G Amendment 1 would introduce new cleanliness requirements to the industry, and IPC-WP-019A would be there to help companies wishing to start the Implementation.

In 2020, the CPI J-STD-001H was released. The revision of this document included changes to the cleanliness section, including additional information on the objective supporting evidence required when qualifying a manufacturing cleaning process. Supporting objective evidence is test data demonstrating that product performance is not adversely affected in the service environment of Class 2 and Class 3 products. This may include test data from surface insulation resistance (SIR) tests, possibly in combination with ion chromatography (IC), historical evidence demonstrating that the residues did not cause in-service failures, and electrical testing with energized for periods extreme temperatures and humidity that represent the end-use environment. These changes prompted the Rhino team to further revise the IPC-WP-019 to ensure that the explanations and industry support remain up to date.

Today, IPC-WP-019B continues to support the industry and provide the necessary explanations and information to help businesses use the cleanliness requirements of IPC J-STD-001H. This is the user manual behind the requirements.

For more information or to purchase IPC-WP-019B, visit IPC.org.

Debora Obitz is responsible for IPC technical programs.

This article appeared in the July 2021 issue of Charger SMT007.


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