Influence of flux activity on process parameters and solder joints in lead-free wave soldering

In order to solve the typical soldering defects in lead-free wave soldering, the Design of Experiment(DOE) was conducted to optimize the process parameters. Based on the printed circuit board(PCB) experimental results, the method of Analytic Hierarchy Process(AHP) was employed to analyze the experiment results quantitatively. Then the influential weights of each factor in different levels were obtained. It is concluded that the influential sequences of the four main process parameters in lead-free wave soldering are track speed, flux quantity, soldering temperature and preheat temperature; the optimal process parameters are as follows: flux quantity 40mL•min-1, preheat temperature 110°C, track speed 1.6m•min-1, soldering temperature 265°C. Furthermore, the reasons of solder bridging and missing weld defects were discussed systematically according to the analysis results. This paper reveals the key direction to optimize the process parameters and provides an effective measure to improve the soldering quality in lead-free wave soldering.

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An Experimental Study of Lead-Free Wave Soldering Using SAC 305 and No-Clean Flux

Electronic and Photonic Packaging, Electrical Systems Design and Photonics, and Nanotechnology ◽

10.1115/imece2006-13927 ◽

2006 ◽

Author(s):

Guhan Subbarayan ◽

Buck Warnock ◽

Purushothaman Damodaran ◽

Krishnaswami Srihari ◽

Jorge Arellano

Keyword(s):

Process Parameters ◽

Printed Circuit Boards ◽

Good Control ◽

Lead Free ◽

Optimum Process ◽

Free Wave ◽

Wave Soldering ◽

Hole Fill ◽

Free Process ◽

Flux Chemistry

The transition to lead-free assembly will have a significant effect on wave soldering operations. Since the wetting ability of lead-free solder is usually less than that of tin-lead solder, it can result in unacceptable hole fills and inconsistent top side wetting - especially in the case of thick Printed Circuit Boards (PCBs). Presently, there is very little data available on lead-free wave soldering with tin-silver-copper (SnAgCu or SAC) alloy and no-clean flux chemistry. Although some researchers and consortia recommend tin-copper (SnCu) for lead-free wave soldering, demonstrating the feasibility of using the SAC alloy for wave soldering operation can aid manufacturers to use the same alloy for both reflow and wave soldering operations. In this study, SAC 305 alloy and no-clean flux were evaluated in terms of percentage of hole fill and solderability on a 93 mil thick test vehicle with Immersion Silver (ImmAg) surface finish. The evaluation was performed on a nitrogen equipped wave soldering equipment. It has 4 preheating zones (3 convection bottom heaters and 1 infrared top heater) that provides good control to develop the required preheat profile. A partial factorial experiment was conducted to study the main effects of solder pot temperature, topside preheat temperature and conveyor speed on wave soldering performance. Wave soldering was performed after two reflow cycles. A 100% visual inspection was done for all the through hole components using a 10X microscope to determine top side wetting, percentage of hole fill, bridging, flux residue and solder balling. Thickness of the hole fill was also measured using digital X-Ray equipment. The data generated from this experiment was used to determine the 'optimum' lead-free process parameters for wave soldering using a SAC 305 alloy with a no-clean flux chemistry. The 'optimized' process parameters were then used to evaluate boards with Organic Solderability Protective (OSP) and Electroless Nickel Immersion Gold (ENIG) surface finishes. The designed experiments approach adopted to determine the optimum process settings and the research findings are explained in detail.

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Case study for high volume lead-free wave soldering process with environmental benefits

Proceedings of the 2005 IEEE International Symposium on Electronics and the Environment, 2005. ◽

10.1109/isee.2005.1437002 ◽

2005 ◽

Cited By ~ 2

Author(s):

I. Baylakoglu ◽

S. Hamarat ◽

H. Gokmen ◽

E. Meric

Keyword(s):

High Volume ◽

Environmental Benefits ◽

Lead Free ◽

Free Wave ◽

Soldering Process ◽

Wave Soldering

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Lead-free wave soldering evaluation update

Soldering & Surface Mount Technology ◽

10.1108/ssmt.2003.21915bab.010 ◽

2003 ◽

Vol 15 (2) ◽

Keyword(s):

Lead Free ◽

Free Wave ◽

Wave Soldering

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Stitch-Bond-Shearing in Optoelectronic Devices, Caused by Lead-Free-Wave-Soldering – Do We Need Improved Wire-Bonding Methods?

ISTFA 2008: Conference Proceedings from the 34th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2008p0049 ◽

2008 ◽

Author(s):

Peter Jacob ◽

Michael Rütsch

Keyword(s):

Optoelectronic Devices ◽

Wire Bonding ◽

Lead Free ◽

System Level ◽

Process Window ◽

Free Wave ◽

Reliability Problem ◽

Wave Soldering ◽

Level Process

Abstract This case study shows a typical example of a manufacturing-chain-induced reliability problem. All participants of the chain do their work within specifications, but, looking at the system level, severe reliability problems have been observed. In order to get back into the system-level process window, several corrective actions are possible. In this case, the most promising approach is an improvement of the stitch bond robustness, combined with a clear user specification.

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