Papers by Andy C. Mackie PhD
by Andy C. Mackie PhD , Olivier Lauzeral (iROC)
The names of high-energy subatomic particles such as alpha, beta, gamma, x-rays and cosmic rays will be well known to every high-school student. Table 1 shows some of the most common types of particles and a description of them.
In aerospace electronics, any of these particles may be encountered and each presents a unique challenge for applications, such as satellite telecommunications. Even at sea level, much of the semiconductor packaging experts are aware of the increasing need for controlled alpha-emissions in materials that are immediately adjacent to the chip surface. This need is driven by the shrink in size of the active device (characterized by the “equivalent DRAM gate length”1 ) present in the active device layers of a semiconductor chip.
ultra low alpha, semiconductor packaging
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Posted on 14 Oct 2011
by Chris Nash , Andy C. Mackie PhD
Few things strike more dread in the hearts of technical service personnel than the words: “Is your
flux compatible with material XYZ?” This issue is especially difficult if XYZ polymerizes (cures). The customer’s expectation is that there will be an unequivocal yes-or-no answer, yet there is a myriad of complexities behind which the question that materials suppliers and users alike are sometimes unaware. This question may come from engineers in any of the fields of SMT (surface mount technology) to power semiconductor die-attach to flip-chip underfill.
This paper explains customer fears that lie behind the compatibility question; gives a better concept of what may be in the customer’s mind when they ask if a material is “compatible”; and also explains potential failure modes, main control parameters, and what test methods are currently available to test “compatibility”.
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Posted on 4 Mar 2010
by Andy C. Mackie PhD
In my twenty years in the electronics manufacturing industry, I have heard a lot of claims made about the use of nitrogen in inerted soldering processes: many of them completely wrong.
In this paper, we will talk about reflow in an enclosed oven, although many of these discussions may pertain to wave soldering and even vacuum soldering.
soldering, reflow, electronics manufacturing
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Posted on 24 Jan 2011
by G. Wilson , Mike Fenner , Andy C. Mackie PhD
The use of special purpose solder pastes in power die attach is well-established offering low voiding and
reliable bonding in volume manufacturing. However these materials are designed around high lead alloys and
applied by dispensing. IGBT circuits are made by printing high tin alloys to multiple die sites, placing die and
reflowing in a process more similar to conventional PCB or hybrid thick film assembly. This paper describes
how the opportunity was taken to make use of the latest developments in Pb-free SMT flux technology and re-
optimize them to the different requirements of IGBT die attach.
We rehearse the attributes and requirements of IGBT circuitry and then go on to show how a high
performance Pb-Free solder paste has been developed to meet the requirements of large power die attachment
(LDA) in IGBT module manufacturing processes. The paste has excellent print and handling characteristics and
routinely returns less than 0.5% voiding under large die over a wide range of vacuum reflow conditions. The
flux vehicle chemistry offers ease of cleaning to be compatible with the next stage processes of wire bonding & circuit encapsulation.
Cleaning, wire bonding, void free, die attach, IGBT, solder paste
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Posted on 8 Mar 2010
by Adrian Low, Jim Hisert , Andy C. Mackie PhD
Although there are some unsubstantiated claims that the history of solder reaches back 7000 years (Ref. 1), it seems more likely that the first
gold-tin solders were used in jewelry in the Egyptian Early Dynastic Era, around 5000 years ago (Ref. 2).
Why is solder still the overwhelming choice for interconnects when high-tech alternatives abound? The answer is simple: Solder is the only electrically conductive
joining material that is so compatible with the metal surface it is joining to that it intermingles on the atomic level.
Solder Melting, solder alloy, solder, pb-free, Flux Cleaning, flux, BGA, ball attach
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Posted on 15 Oct 2009
by Jim Hisert , Andy C. Mackie PhD
Ball-attach fluxes for
solder sphere attachment processes are just one example of how fluxes used within the semiconductor market have evolved significantly. Process needs for water-soluble fluxes have sparked the necessary advancements for developing products that meet these
requirements.
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Posted on 10 Mar 2010
by Jordan Ross , Andy C. Mackie PhD , Dave Saums, Bob Jarrett
The rise in the heat flux and total power dissipated from semiconductor devices has been well documented in semiconductor packaging industry forecasts. [1, 2, 3] This increasing heat flux (power per unit area, or power density) is not limited to microprocessors and server processors. This general trend affects a variety of commercial and military power semiconductor devices as well as integrated circuits (IC).
The primary determinant of a thermal solution for a semiconductor device or module is the overall heat dissipation. However, at a macro level, the localized heat flux is typically a more critical concern for device reliability. Hot spots with extremely high heat fluxes are a significant concern in the thermal management of processors, RF, wide band gap, power LED, and other semiconductor devices.
indium metal, phase change materials, TIM, thermal management
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Posted on 1 Jul 2009
