During the process from wafer fabrication to completing the final plastic package there are a number of upstream processes that negatively impact subsequent operations. Problems at wirebond can be traced directly to both fab and saw operations. Analysis of bond pads from the fab reveal traces of flourine that can lead to the formation of HF which is highly corrosive to aluminum and some passivation materials. Most post fab processing operations such as test maintain high humidity levels to minimize ESD/EOS damage to the die. The same high moisture level conditions that are required to minimize ESD/EOS damage supply the necessary moisture to cause trace halogens to form HF causing further corrosion on the bond pads.
Provided with an infinite source of H2O,the flourine becomes a reactive ion that seeks aluminum to form aluminum fluorides. In this reaction the halogen ion is liberated and OH ions in the water reacts with Al to form Al (OH)x and then AlOF. Some of the AlOF becomes AlO and frees the F to become HF. The halogen can now react with a new aluminum atom to repeat the process forming layers up to hundreds of angstroms thick. To terminate the process the flourine has to be eliminated else wire bond ends up with a bond pad that is both difficult to process and can lead to long term reliability issues.
This paper discusses how to remove those halogens,eliminate saw corrosion and improve wirebonding without the use of legacy argon plasma solutions which only serve to redeposit both detectable carbon and halogen elsewhere on the wafer/die. This process also demonstrates a solution that is less than a “milli-penny” per die compared with the expensive and unreliable argon plasma. Results to date have shown that not only can corrosion be eliminated at saw but the die received at wirebond has a thinner oxide layer than material leaving the fab (~20A).

The electronics industry continues to strive to provide more environmentally friendly products. This movement is partly due
to legislation from various countries,partly due to public outcry from well publicized 3rd world recycling practices,and partly due to non-government organizations (NGOs) testing and publishing information on electronic devices regarding their content of various toxic materials. One set of materials targeted for reduction and eventual elimination are halogenated compounds. Halogens are found in plastics for cables and housings,board laminate materials,components,and soldering fluxes. Replacing these halogenated compounds can have a dramatic affect on the PCB assembly process. In this paper those challenges will be discussed as well as techniques and practices that will help ensure high end of line yields and continued reliability.

Since the early days of PWBs,liquid photoresists and soldermasks have played indispensable roles in the manufacturing process. From the introduction of the original Kodak Photo Resist (KPR) and PC 301 soldermask,development has sought to keep pace with the improved resolution,processing speed,and advanced substrates demanded by the industry. Similar to the path taken in micro lithographic processing,PWB photoresist and soldermasks have evolved on solvent based coating platforms. In the new millennium,point-of-manufacture and downstream health issues have come to the fore. Water,soil and air pollution are key drivers and preventative measures have a real economic impact on the manufacturer. Further,as global warming is a reality and oil prices continue to rise,manufacturers are looking for ways to decrease their environmental impact and reduce cost without sacrificing performance. But what are the environmental impacts of liquid photoresist and soldermask? And what are the associated costs? This paper will analyze the following in relation to both the environmental,health and related cost impacts:
- Current photoresist and soldermask formulations
- Application methods
- Medical and health concerns
- Hidden costs such as insurance,shipping and handling
In addition,the paper will describe the environmental,performance and cost impacts associated with utilizing a new water-based photoresist platform.

Green Design has recently gained significant interest in the electronics industry all over the world and will remain one of the
hottest topics for the upcoming years. Besides reduction of consumed energy,Original Equipment Manufacturers (OEMs) are increasingly restricting the use of certain halogens as flame retardant substances in plastics. For some low- to midtemperature
thermoplastics,halogen-free solutions of comparable performance are commercially available. However,for certain high-temperature plastics,which are typically used in connectors and sockets,there may be no drop-in solution that meets the engineering and cost targets. Further,these new materials require re-qualification of connectors and typically need new capital expenditures for mold tooling to account for changes in processing and shrinkage. In certain areas OEMs and connector manufacturers may face a significant impact on processing or electrical and mechanical performance as well as on the total system cost. In this paper we review the current industry status with respect to the introduction of halogen-free plastics and will discuss various options to implement Green Design solutions. These alternatives allow a significant reduction or elimination of halogens without jeopardizing product performance,safety or cost; in some cases,the material similarity will reduce connector re-qualification or retooling costs. The concept of Green Design is derived from the
IEC62368 standard,which is currently being discussed as a global standard within the electronics industry covering audio/video and IT-equipment.

Previously,the general understanding about polymer-base thick film flexible circuits consisted of low density with low electrical conductivity because of the organic matrix in the conductor materials. Additionally,the organic matrix of these traditional circuits does not allow any soldering. These are the major reasons why thick film circuits did not become the mainstream technology of the industry even though the technology provides much lower manufacturing cost compared with the traditional copper-etched circuits.

Many flat panel display technologies were developed and commercialized since 1980s. Today,liquid crystal display panels
(LCD) and plasma display panels (PDP) have the lion’s share of the large size flat panel displays,but there may be some new contenders waiting in the wings. There is a demand to produce even thinner large panel displays,or even make them flexible. The organic EL display (OLED) is one of the new display technologies engineers developed. OELD is successful in reducing the thickness of the flat panel TV; however,OELD’s manufacturing costs is much higher compared to LCDs or PDPs because of a long complicated photolithography process and expensive fluorescence materials required during production.
The solution is to use a screen-printing process that is capable to generate patterns with fewer steps compared photolithography and etching process. A series of advanced screen-printing process were developed to build functional circuit constructions for both active and passive components. In this study,the advanced screen-printing technology was applied to generate low electronic fluorescence patterns on flexible substrates to show the possibilities of low cost flexible displays.

In today’s manufacturing world,higher equipment utilization and lower operating cost is the way forward. Newer machineries are usually well equipped to get the job done as they are manufactured with the latest available technology whereas the earlier generation equipments are usually phased off or go through a series of improvements to meet the goals but at the expense of higher cost. The RFS handler is a good example of older generation equipment,making an impact with the help of TRIZ or Theory of Inventive Problem Solving in this ever demanding manufacturing world.
The Cone area of the RFS handler is made up of 2 perpendicular chuck heads that is used to pick up units (vacuum strength) from a horizontal position,rotates 90° and sockets the unit vertically at the TIU (Tester Interface Unit) for electrical testing. However,the many connections present from the vacuum generator right up to the suction cup of the cone chuck,cause the suction strength to be low. This,coupled with the centrifugal force of the rotating chuck,causes the unit to potentially drop,leading to high assist and downtime. In addition,we see that the high maintenance cost of the RFS handler is specifically coming from the Nest.
By adopting TRIZ,we used 2 concepts to solve the issues faced. Merging was used to solve the many connection problems present by removing the excessive components through the trimming process. There was also a change in suction cups. By doing so the suction strength has doubled without even changing the vacuum generator and the number of missing unit cases has reduced significantly by 82 %. The Cone related jams has reduced by another 78 % which in other words increases the Mean Time Between Assist by 120 %. Next,we used Segmentation for the Nest. The Nest being an ESD sensitive material is one of the most expensive consumable parts in the handler. By breaking the Nest up into 3-pieces,we now only change the affected part that is worn off and not the whole piece. This simple modification together with the change in suction cup helps us save 35 % on our monthly Preventive Maintenance cost. In the larger picture,we are looking at a projected savings of >US$800K throughout other Intel sites.

With greater time to market and time to volume pressures,manufacturers of populated printed circuit boards have traditionally relied upon un-powered vectorless testing to quickly and reliably identify open pins on integrated circuit devices and connectors that reside on populated PCB assemblies. Unfortunately with the advent of higher speed signals,PCB designers can no longer tolerate the negative transmission line effects of test pads that are used to gain electrical access during in-circuit testing. An improved vectorless test method has been developed to address the loss of test coverage on high speed signals that reside on contemporary printed circuit board assemblies. This technology can quickly and effectively identify open connections between a boundary scan based device and other connected devices including a non-boundary scan device,a connector,or a socket. A discussion of this new vectorless test method,employing virtual access,is the focus of this paper.

The areas of entrapment on cleaned and no-clean assemblies are showing higher levels of contamination around BGA’s,in microvias and particularly under components like the QFN. Flux residues trapped under and around low standoff components that are causing leakage paths are negatively impacting field performance,and are showing up as no trouble found return more often than ever. Microvias are corroding open during soldering due to the contamination from fabrication found in vias from the etch steps and poor cup rinsing of the plugged vias. This paper will cover techniques for investigating pockets of contamination using a localized extraction method and ion chromatography analysis to establish root cause,and the development of corrective action plans for field failure projects. Defining,implementing and monitoring corrective action plans for the failed assemblies has allowed us to understand the processing variables,and optimize the critical parameters that meet the performance needs of today’s technology.

Moore’s Law infers that the number of transistors on a chip doubles approximately every two years. Consistent with Moore’s Law,high reliability electronic devices build faster processing speed and memory capacity using increasing smaller platforms. The trend toward highly dense assemblies reduces the spacing between conductors while yielding a larger electronic field. As the industry moves to higher functionality,miniaturization,and lead-free soldering,studies show that cleanliness of the assembly becomes more important. Residues under low standoff components,with gaps less than 2 mils,represent an increasingly difficult cleaning challenge. Collaboration from cleaning equipment and cleaning material companies has led to innovations for improving throughput and complete residue removal under low standoff components. The purpose of this paper is to report both mechanical and chemical innovations that open the process window.