CHEMISTRY AND SURFACE ANALYSIS

The Ion Chromatography (IC) is an analytical technique which divides ions and polar molecules depending on their charge. Every species interacts in a different way with the stationary phase (a column full of resin), and they have different retention times. This feature allows to quantify them individually after being separated. The test procedure is designed to measure the ionic contamination level extractable from the surface of printed circuits and assemblies, soldering fluxes, electrical components, etc.
Test method: IPC TM 650 2.3.28 (Ionic Analysis of Circuit Boards, Ion Chromatography Method), IPC TM 650 2.3.28.1 (Halide Content of Soldering Fluxes and Pastes), IPC TM 650 2.3.28.2 (Bare Printed Board Cleanliness by Ion Chromatography)

The Optical Emission Spectrometry (OES) is an analytical technique which allows to identify the traces of metal and uses the Inductively Coupled Plasma (ICP) to separate the sample into atoms and ions, that opportunely excited, release an electromagnetic radiation of different wavelength according to each element.
This test allows to determine the basic quality and quantity composition of the analysed sample.
Our chemical lab is also able to determine the carbon and sulphur concentration into metal alloys through a carbon and sulphur analyser (LECO). The application field of this analysis includes metals like steel, iron, copper, alloys, etc.

The contact angle is a thermodynamic quantity which represents a measurement of wettability. This test measures the angle a drop of a liquid creates on the surface of a solid. The size of the contact angle between the liquid and the solid depends on the interaction between the substances and the contact surface. Lesser the interaction, greater the contact angle and it will be more difficult to wet the solid, which will have a lesser adhesion to foreign bodies. From the contact angle determination, it is possible to define some features of the surface like, for example, the surface energy.
Test method: ASTM D7490 Standard Test Method for Measurement of the Surface Tension of Solid Coatings, Substrates and Pigments using Contact Angle Measurements
Test method: ASTM D7334 Standard Practice for Surface Wettability of Coatings, Substrates and Pigments by Advancing Contact Angle Measurement

The Glass Transition Temperature is usually indicated with the symbol Tg, and it represents the temperature range at which an amorphous material moves from a hard, glassy condition to a more flexible, rubbery condition. This phenomenon is the so-called structural relaxation.
It is possible to define the Glass Transition Temperature by using different instruments:
– TM 2.4.24C Glass Transition Temperature and Z-Axis Thermal Expansion by TMA
– TM 2.4.25C Glass Transition Temperature and Cure Factor by DSC
– TM 2.4.24.2 Glass Transition Temperature of Organic Films – DMA Method

The Coefficient of Thermal Expansion describes how the size of an object can change in relation to a temperature variation. Usually, the substances expand themselves when their temperature changes and the relative expansion or reduction can occur in all the directions (isotropic material)
Test method: IPC TM650 2.4.24 (Glass Transition Temperature and Z-Axis Thermal Expansion by TMA)

The Time to Delamination is a measurement used to evaluate the basic material performance: it provides with an information about the time the resin and the copper require to separate or delaminate themselves. This test uses the TMS instrument to bring a sample (laminated or a printed circuit) at a specific temperature, and it measures the necessary time for the delamination.
Test method: IPC TM 650 2.4.24.1 (Time to Delamination (TMA Method))

The Thermogravimetric Analysis measures the variation of the sample mass subjected to a heating with a controlled growth of the temperature. The result of the analysis includes a thermogram which indicates temperature/time on the x-axis and the absolute change or sample mass percentage on the ordinates (Thermal Decomposition Curve). This analytical technique is useful to evaluate the decomposition and oxidation processes.
Test method: IPC TM 650 2.4.24.6 (Decomposition Temperature (Td) of Laminate Material Using TGA)

The Differential Scanning Calorimetry (DSC) is a method that, considering the temperature, measures the difference between the thermal fluxes in a sample substance and into a reference, both subjected to a controlled temperature variation. This technique provides with information about the quantity of energy absorbed or released by the sample when it is warmed or cooled.
The common Melting Point of a material is identified with the temperature at which it changes its condition from solid to liquid. During this process, all the energy added to a substance is consumed as heat of fusion and the temperature remains constant. The analysis of Melting Point allows to obtain a first impression about the purity of a substance because some impurities change the fusion range.

The solder pastes are suspensions of stable and homogeneous particles of the soldering powder immersed into a liquid flux. By changing the size, the distribution, and the shape of the soldering particles, it is possible to control the rheology and the performances of the pastes.
1. Solder Ball Test – This test is performed to determine the solder paste re-flow properties during the re-fusion process.
Ref. Standard IPC TM 650 2.4.43 (Solder Paste – Solder Ball Test)
2. Slump Test – This test defines the vertical and horizontal slump of the solder pastes.
Ref. Standard IPC TM 650 2.4.35 (Solder Paste – Slump Test)
3. Wetting Test – The wetting test defines the ability of a solder paste to wet an oxidised copper surface and allows to examine, from the quality point of view, the spatter quantity of the solder paste during the re-fusion process.
Ref. Standard IPC TM 650 2.4.45 (Solder Paste – Wetting Test)

The water absorption test is performed to determine the quantity of absorbed liquid in specific environmental conditions. This analysis is affected by factors like the type of material, the additives used, the temperature and duration of the test. The results show the possible performances of the materials into water or in humid environments.
Test method: IPC TM 650 2.6.2.1 (Water Absorption, Metal Clad Plastic Laminates) – Determining of the absorbed water quantity by plastic laminates immersed into distilled water for 24 hours.

The flammability is the capacity of a material to burn or explode by causing fires or combustion. The level of difficulty necessary to provoke the combustion of a substance is determined by the flammability test.
Ref. Standard: UL94 (The Standard for Flammability of Plastic Materials for Parts in Devices and Appliances) – Applicable to plastic material, it can determine the materials’ ability to propagate or put out a flame after having lighted it.

This test allows to detect the active substances inside the fluxes. The solder paste or the flux are placed on a substrate covered with a light copper layer. The presence (or not) of active substances will cause the removal of the copper layer on the substrate by allowing to understand the corrosive behaviour of the flux.
Test method: IPC TM 650 2.3.32 (Flux Induced Corrosion (Copper Mirror Method)), IPC J-STD-004 (Requirements for Soldering Fluxes)

The corrosion tests are essential to understand how the materials behave in severe or ongoing use conditions, and they can guarantee the achievement of the complete life cycle. This test eases the prediction, the planning, and the mitigation of the negative effects the corrosion can have on the materials on which they can be used.

GEST Labs can test samples and materials to evaluate their porosity features and to characterise the empty spaces inside of them.

Test method: IPC TM 650 2.3.24 (Porosity of Gold Plating), Standard IPC 4552 (Specification for Electroless Nickel/Immersion Gold (ENIG) Plating for Printed Circuit Boards)