Effect Of Flux Residues Research Articles

Investigation of the effect of solder flux residues on RF signal integrity using real circuits

PurposeProvide information on the effects of flux residues from surface mount assembly on radio frequency (RF) performance.Design/methodology/approachA series of test vehicles designed to evaluate the RF performance on various test patterns and some simple circuits. Empirical testing is used in determining the data.FindingsProvides a methodology for checking the performance of flux residues as well as information on the performance of a few different flux residue types.Research limitations/implicationsThis is not an all encompassing project and the results may not extrapolate out to higher frequency ranges.Practical implicationsA good source of reference that can be used to understand the impacts of the assembly process on RF performance.Originality/valueThis paper shows the effect of assembly materials (flux residues) on a real circuit and not just test patterns. It can give a basic understanding to process engineers of the potential impact of the assembly process on a RF circuit.

An investigation into the effects of flux residues on properties of underfill materials for flip chip packages

Flux is necessary to promote wetting between solder and metallized surfaces during flip chip bonding process. However, flux residues are unavoidable and may have detrimental effects on the properties of the underfill materials. In this study, the effects of flux residues from a commercial no-clean flux on two types of underfills were systematically investigated using a contact angle goniometer, thermal mechanical analyzer (TMA), thermogravimetric analyzer (TGA) and dynamic mechanical analyzer (DMA). It was found that the presence of flux residue reduced the glass transition temperatures (Tg) of both cured underfills studied. Although /spl alpha//sub 1/ (CTE below Tg) of cured underfills were slightly affected, /spl alpha//sub 2/ (CTE above Tg) increased significantly. The DMA tan/spl delta/ curves of flux residue contaminated samples were found to be broader than those of pure underfills. In addition, the rubbery storage moduli of underfills contaminated with flux residues also decreased significantly. The existence of flux residues was found to increase the moisture absorption of the cured underfills.

Surface Mounting Reliability

A review is given of the reliability of the ceramic chip carrier when solder‐attached to alumina thick film substrates. It is shown that no degradation occurs during humidity cycling or humidity steady state tests. Some diminution of the solder joint strength takes place during prolonged high temperature storage and temperature cycling but the effect is much more marked during power cycling. The effect of flux residues on thick film hybrids after solder reflow of surface mount components is assessed. No significant deterioration of any component, printed or discrete, that is attributable to flux is observed, given adequate cleaning techniques. The reliability of the ceramic leadless chip carrier is compared with both leaded ceramic and metal and plastic surface‐mountable components. The compliant leads of packages offer some advantages over the leadless chip carrier where thermal excursions are important but the leads themselves are easily damaged. Plastic packaging for surface‐mountable components continues to improve and become increasingly popular but potential reliability hazards associated with a thermal management performance inferior to that of ceramic and metal versions, moisture ingress and corrosion are seen to remain problem areas.