IPC/EIA/JEDEC J-STD-001, J-STD-002, J-STD-003; IPC-TM-650; Method 2.4.12; MIL-STD-202; Method 208;
MIL-STD-883 Method 2003.10
Solderability testing is the method to provide a means of evaluating the solderability of electronic terminations (i.e., component leads, lugs, terminals, wires, etc.). The Solderability of device package terminations that are intended to be joined to another surface using SnPb or Pb-free solder for the attachment. This test procedure, considered to be a destructive test, is utilized to determine whether the processes packaging materials used during the manufacturing operations produce a component that can be successfully soldered in the next level assembly.
Solderability evaluations are made to verify that the solderability of component leads and terminations meets the requirements established in the procurement standard and to determine that storage has no adverse effect on the ability to solder components to an interconnecting substrate. Determination of Solderability can be made at the time of manufacture, at receipt of the components by the user, or just prior to assembly and soldering.
Most common Industry Standards for performing Solderability Testing include:
There are several methods by which solderability testing is performed. However, the two most commonly used methods are:
- Wetting Balance Analysis
- The “Dip and Look” Method
In each of these test methods, the samples are typically required to undergo an accelerated aging process prior to being tested for solderability.
The solderability of a surface is defined by its solder wetting characteristics. Solder wetting pertains to the formation of a relatively uniform, smooth, and unbroken film of solder that exhibits excellent adherence on the soldered surface. Non-wetting, on the other hand, is the condition wherein the solder coating has contacted the surface but did not adhere completely to it, causing the surface or a part thereof to be exposed. De-wetting is the condition wherein the solder recedes after coating a surface, creating irregular mounds of solder, but leaving behind no exposed areas.
Solderability testing utilizing the Wetting Balance Analysis is a quantitative test, measuring the wetting forces imposed by the molten solder on the test surface as it is dipped into and held in the solder bath as a function of time, which is recorded. The recording (graph) is initiated when the wetting force being negative (non-wet condition), which rises until it crosses the zero axis of wetting force, indicating that wetting has occurred. The time it takes for wetting to occur is one parameter used to determine solderability.
The “Dip and Look” Method, is widely used in Quality process control and for reliability monitoring. It is a qualitative test process to determine whether a sample passes or fails the test based on the physical and visual attributes that the test sample exhibits after testing is performed.
Solderability testing, utilizing Wetting Balance Analysis technology, is a measurement of the weight and speed with which the solder meniscus climbs upwards on the component lead dipped in molten solder. When properly performed, the Wetting Balance measurement is recognized as the most accurate, quantitative method for measuring, testing and recording solderability of the sample being testing.