Lead-free reflow puts new demands on rework equipment
5 May 2004Manufacturing / Production Technology, Hardware & Services
Security Services & Risk Management
Lead-free solder is a subject that must be addressed today because it will be a requirement soon. The process parameters required for high reliability solder joints put new and tougher demands on reflow and rework equipment. The hot air rework systems that are currently used for BGA rework will have a difficult time trying to achieve a proper lead free profile. However, Ersa's IR technology is perfectly suited to meet these lead-free demands.
Forced convection
Forced convection reflow systems are the standard in the industry for production. Quality lead-free BGA reflow can be achieved in the enclosed environment of a reflow oven. Rework, however, cannot be done in a completely enclosed environment. The heating conditions required for lead free BGA reflow are difficult to achieve when blowing hot air through a nozzle (Figures 1 and 2).
Figure 1. The air flow dynamics in a hot air rework nozzle are difficult to control and, depending on the nozzle construction, can lead to hot and cold spots on the package
Figure 2. Two separate hot air rework nozzles were lowered down to a heat sensitive surface and the reflow program was started. The burn patterns shown here indicate how the heated air molecules move in the nozzle and transfer heat to the component. Dark areas are hotter
The process
The process window for lead-free solder paste reflow is much tighter than for eutectic or low melt alloys (Graphs 1 and 2). The activation time is sacrificed in order to reduce the oxidation which takes place much faster in the absence of lead. The reflow or rework heating system must be able to achieve the optimal soak from 150 to 220°C in 50 seconds also on heavy thermal mass PCBs. Slow heat rework systems, like hot air, can take too long in this critical phase, causing oxidation to form during soak.
Graph 1. Kester reflow profile for lead-free alloy (SnAgCu)
Graph 2. Typical eutectic paste profile
Due to the increase in temperature range and the tight process window, controlling the DT across the entire PCB in reflow and across the complete area array package in rework will be the ultimate challenge. Most hot air rework systems are poorly suited to meet these tougher demands. Ersa's 2nd generation proprietary IR technology was specifically designed for lead-free BGA rework.
By using the closed-loop reflow technology (Figure 5) of Ersa's 1600 W IR 550 A a perfect process window can be guaranteed, with uniform heat distribution with minimum DT, and proper peak temperature for high reliability lead-free solder joints.
Figure 3. The dark areas are hotter, revealing nonuniform heat distribution across the package. This DT is unacceptable for lead-free solders and will cause oxidation to form in the lighter areas
Figure 4. The ERSA IR technology guarantees minimum DT across the entire BGA package
FineX: Makes shielding clear Avnet Abacus
Manufacturing / Production Technology, Hardware & Services
Panasonic Industry launches high-transparency, low-resistance, flexible transparent conductive film for electromagnetic wave shield with pre-applied OCA.
Read more...Echoes of 2018? Follow-up on Woolworths explosions Technews Publishing
News & Events Security Services & Risk Management Retail (Industry) Facilities & Building Management
SMART Security Solutions follows up with Jimmy Roodt to find out more about an old connection to the Woolworths bombings from 2018. The investigation remains ongoing.
Read more...Next-generation cash-in-transit vehicle
News & Events Security Services & Risk Management
Fidelity Services Group has unveiled a new, purpose-engineered Cash-in-Transit (CIT) vehicle designed to redefine crew protection, deter threats, and enhance operational resilience in an increasingly complex criminal environment.
Read more...AURA partners with Discovery to launch Discovery 911
News & Events Security Services & Risk Management
AURA has announced a partnership with Discovery Insure to power the security-response component of its new Discovery 911 virtual panic-button offering, which is available through the Discovery Insure app.
Read more...Collaboration is now critical RS South Africa
Manufacturing / Production Technology, Hardware & Services
The message emerging from RS Connect is clear: Organisations can no longer rely on internal optimisation alone to secure performance. Competitive advantage is increasingly being determined by the strength of external relationships, shared capability and coordinated action across value chains.
Read more...Disruption is the new normal. Effortless is the new competitive advantage. Seven Labs Technology
Manufacturing / Production Technology, Hardware & Services
Global supply chains have been under pressure for years. The manufacturers still standing are the ones who stopped waiting for normal to return, and started building something better.
Read more...Global security in 2026
Editor's Choice News & Events Security Services & Risk Management Industrial (Industry) Mining (Industry)
The World Security Report 2026 states: “In a world of increasing volatility, physical security has evolved. It is no longer just a defensive measure; it is a critical driver of corporate value.”
Read more...Who is to blame for autonomous mistakes?
Editor's Choice Security Services & Risk Management Industrial (Industry) Mining (Industry)
Most supply agreements for AI-integrated equipment still closely resemble plant hire contracts from ten years ago: bilateral, human-focused, and silent on who bears the risk when a machine makes a decision on its own.
Read more...The post-Q1 security checklist
Asset Management Security Services & Risk Management
By this time of year, employees have changed jobs or roles, suppliers may have changed, and devices have moved between offices, homes, and sites. This is the right time for businesses to run a practical post-Q1 security check.
Read more...PoPIA turns its attention to gated access
News & Events Security Services & Risk Management
The Information Regulator has gazetted its proposed Code of Conduct for the processing of personal information at gated access points. At 65 pages long, the code signals a significant shift in how personal information is collected and managed at entry points.
While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements and company contact details are published as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material.
printer friendly version