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J-STD-004C: The Most Comprehensive Standard for Soldering Fluxes - Download It for Free

J-STD-004: What Is It and Why You Need It


If you are involved in soldering electronic components, you know how important it is to use the right soldering flux for your application. Soldering flux is a chemical agent that helps to clean, wet, and bond the metal surfaces during soldering. However, not all soldering fluxes are created equal. Some may be too aggressive, leaving corrosive residues that can damage your circuit board. Others may be too weak, failing to provide adequate wetting and adhesion. How can you ensure that you are using the best soldering flux for your needs?

That's where J-STD-004 comes in. J-STD-004 is a joint industry standard that prescribes general requirements for the classification and characterization of soldering fluxes for high quality solder interconnections. This standard may be used for quality control and procurement purposes, as well as for optimizing your soldering process. In this article, we will explain what J-STD-004 is, what are its benefits, how to classify and characterize soldering fluxes according to it, how it compares with previous versions, and how to apply it in your soldering process.

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What is J-STD-004?

J-STD-004 is a standard developed by the Flux Specifications Task Group (5-24a) of the Assembly and Joining Processes Committee (5-20) of IPC, a global trade association dedicated to the competitive excellence and financial success of its member companies which represent all facets of the electronics interconnect industry. The purpose of this standard is to classify and characterize tin/lead and lead-free soldering flux materials for use in electronic metallurgical interconnections for printed circuit board assembly. Soldering flux materials include the following: liquid flux, paste flux, solder paste, solder cream as well as flux-coated and flux-cored solder wires and preforms.

The standard defines four types of flux materials based on their composition: rosin (RO), resin (RE), organic (OR), and inorganic (IN). Each type of flux material is further classified according to its activity level (from low to high) and its reliability of residue (from low to high) from a surface insulation resistance (SIR) and electromigration standpoint. The standard also specifies whether or not the flux material contains halide activators, which are compounds that enhance the cleaning and wetting properties of the flux but may also increase its corrosiveness. The standard uses a three-character designator to identify both composition and type of fluxes, such as ROL0 (rosin-based flux with low activity and low reliability) or ORH1 (organic-based flux with high activity and high reliability with halides).

What are the benefits of J-STD-004?

Using a soldering flux that complies with J-STD-004 has several benefits for your soldering process and product quality. Some of these benefits are: - You can select the most suitable flux for your application based on its composition, activity, reliability, and halide content. This can help you achieve optimal wetting, spreading, and bonding of the solder joints, as well as minimize defects such as voids, bridges, and icicles. - You can reduce the risk of corrosion and contamination of your circuit board by using a flux that has a low or no halide content and leaves a benign or removable residue. This can improve the electrical performance and reliability of your product, as well as extend its service life. - You can simplify your quality control and procurement processes by using a standard that is widely recognized and accepted by the industry. This can help you avoid confusion and inconsistency when dealing with different suppliers and customers, as well as comply with regulatory requirements and environmental standards.

How to classify and characterize soldering fluxes according to J-STD-004?

To classify and characterize soldering fluxes according to J-STD-004, you need to perform a series of tests on the flux materials to determine their properties and performance. These tests include: - Flux composition analysis: This test determines the type and amount of ingredients in the flux material, such as rosin, resin, organic acids, inorganic acids, activators, solvents, etc. This test is done by using analytical methods such as gas chromatography (GC), infrared spectroscopy (IR), or ion chromatography (IC). - Flux activity level: This test measures the ability of the flux material to remove oxides and other contaminants from the metal surfaces during soldering. This test is done by using methods such as wetting balance (WB), wetting force (WF), or spread factor (SF). - Flux residue reliability: This test evaluates the effect of the flux residue on the electrical characteristics and corrosion resistance of the soldered assembly. This test is done by using methods such as surface insulation resistance (SIR), electromigration (EM), copper mirror (CM), or corrosion (COR). - Flux halide content: This test determines the presence and amount of halide activators in the flux material, such as chloride, bromide, iodide, or fluoride. This test is done by using methods such as potentiometric titration (PT), ion selective electrode (ISE), or ion chromatography (IC). Based on the results of these tests, the flux material is assigned a three-character designator that indicates its composition and type according to J-STD-004. For example, a flux material that has a rosin-based composition, a low activity level, a low reliability of residue, and no halide content would be classified as ROL0.

J-STD-004: A Comparison with Previous Versions

J-STD-004 is not a new standard. It was first published in 1995 as a replacement for MIL-F-14256F, which was a military specification for soldering fluxes that was widely used in the electronics industry. Since then, J-STD-004 has been revised several times to keep up with the changes and challenges in the soldering technology and market. The latest version of J-STD-004 is J-STD-004C, which was published in 2018. In this section, we will compare J-STD-004C with its previous versions: J-STD-004B, which was published in 2011, and J-STD-004A, which was published in 2008.

What are the main differences between J-STD-004A and J-STD-004B?

The main differences between J-STD-004A and J-STD-004B are: - J-STD-004B introduced a new flux type: inorganic (IN), which is composed of inorganic acids and salts. This type of flux is mainly used for soldering aluminum and other metals that require a high activity flux. J-STD-004A did not have this flux type and only recognized three types of fluxes: rosin (RO), resin (RE), and organic (OR). - J-STD-004B added a new test method for flux halide content: ion selective electrode (ISE), which is a more sensitive and accurate method than potentiometric titration (PT). J-STD-004A only used PT as the test method for flux halide content. - J-STD-004B revised the test methods and acceptance criteria for flux residue reliability, especially for surface insulation resistance (SIR) and electromigration (EM). J-STD-004B increased the test duration, test voltage, and test temperature for SIR and EM tests, as well as lowered the minimum acceptable SIR value and the maximum acceptable EM value. These changes were made to reflect the higher reliability requirements for modern electronic assemblies that operate at higher temperatures and voltages. J-STD-004A used less stringent test methods and acceptance criteria for flux residue reliability.

What are the main differences between J-STD-004B and J-STD-004C?

The main differences between J-STD-004B and J-STD-004C are: - J-STD-004C updated the definitions and terminology of some flux terms, such as rosin, resin, organic, inorganic, activator, solvent, etc. J-STD-004C also added some new terms, such as water-soluble flux, no-clean flux, low-residue flux, etc. These changes were made to clarify the meaning and scope of these terms and to align them with other industry standards and documents. - J-STD-004C modified the classification scheme of flux materials by adding a fourth character to the designator that indicates whether or not the flux material is water-soluble. Water-soluble fluxes are those that can be removed by water or water-based solutions without leaving harmful residues. Water-soluble fluxes are designated with a "W" at the end of the designator, such as ROL0W or ORH1W. Non-water-soluble fluxes are those that require other solvents or methods to remove them or are designed to be left on the assembly without causing harm. Non-water-soluble fluxes are designated with an "N" at the end of the designator, such as ROL0N or ORH1N. - J-STD-004C added a new test method for flux activity level: spread factor (SF), which is a visual method that measures the degree of spreading of a solder droplet on a copper coupon after applying a flux material. SF is expressed as a percentage of the area covered by the solder droplet relative to the area of the copper coupon. SF is an alternative method to wetting balance (WB) and wetting force (WF), which are instrumental methods that measure the force or weight change of a solder droplet on a copper coupon after applying a flux material. SF is considered to be more representative of the actual soldering process and more suitable for low activity fluxes.

J-STD-004: How to Apply It in Your Soldering Process

Now that you know what J-STD-004 is and how it compares with previous versions, you may wonder how to apply it in your solder

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