Tag: PCB

Harmonia Philosophica papers

Photo by Spiros Kakos from Pexels

This page contains scientific papers published by Spyridon Kakos, in the context or outside the context of the Harmonia Philosophica program.

Through-hole plating with Polypyrrole in Printed Circuit Boards

Abstract:  The goal of this paper is to investigate the use of polypyrrole (PPy) in the through-hole plating (PTH) stage of the Printed Circuit Boards (PCB) manufacturing process. The method includes: etching of FR4, in situ deposition of a thin film of PPy, resulting in a FR4/ PPy electrode.Copper plated holes of FR4 multilayer PCB specimens were analyzed with the help of optical microscopy, Scanning Electron Microscopy (SEM) and EDS analysis. Tests on polypyrrole coated and copper plated holes also included conductivity and peel strength tests. Findings show that polypyrrole can be an equally good substitute for standard methods of hole-plating methods, like the ones based on palladium, carbon or graphite. Optical microscopy results indicate that a coherent copper layer is formed on the polypyrrole modified surface of the holes. The results of the SEM analysis help understand the mechanism of copper plating and show that copper nucleation is progressing with dendrite structures on the polypyrrole surface, following high conductivity paths. Improvements of the process of the specimens’ pre-treatment, like holes desmearing and stirring of the polymer solution, were also analyzed.

Published at: International Review of Chemical Engineering (I.RE.CH.E.), Vol. 4, n. 2 March 2012.

Through-hole_plating_with_Polypyrrole_in_PCBDownload

From Galileo to Hubble: Copernican principle as a philosophical dogma defining modern astronomy

Abstract: For centuries the case of Galileo Galilei has been the cornerstone of every major argument against the church and its supposedly unscientific dogmatism. The church seems to have condemned Galileo for his heresies, just because it couldn’t and wouldn’t handle the truth. Galileo was a hero of science wrongfully accused and now – at last – everyone knows that. But is that true? This paper tries to examine the case from the point of modern physics and the conclusions drawn are startling. It seems that contemporary church was too haste into condemning itself. The evidence provided by Galileo to support the heliocentric system do not even pass simple scrutiny, while modern physics has ruled for a long time now against both heliocentric and geocentric models as depictions of the “truth”. As Einstein eloquently said, the debate about which system is chosen is void of any meaning from a physics’ point of view. At the end, the selection of the center is more a matter of choice rather than a matter of ‘truth’ of any kind. And this choice is driven by specific philosophical axioms penetrating astronomy for hundreds of years now. From Galileo to Hubble, the Copernican principle has been slowly transformed to a dogma followed by all mainstream astronomers. It is time to challenge our dogmatic adherence to the anti-humanism idea that we are insignificant in the cosmos and start making true honest science again, as Copernicus once postulated.

Published at: International Journal of Theology, Philosophy and Science, Vol 2, No 3, 2018

From_Galileo_to_Hubble_Copernican_dogmaDownload

Consciousness and the End of Materialism: Seeking identity and harmony in a dark era

Abstract: “I am me”, but what does this mean? For centuries humans identified themselves as conscious beings with free will, beings that are important in the cosmos they live in. However, modern science has been trying to reduce us into unimportant pawns in a cold universe and diminish our sense of consciousness into a mere illusion generated by lifeless matter. Our identity in the cosmos is nothing more than a deception and all the scientific evidence seem to support this idea. Or is it not? The goal of this paper is to discard current underlying dogmatism (axioms taken for granted as “self-evident”) of modern mind research and to show that consciousness seems to be the ultimate frontier that will cause a major change in the way exact sciences think. If we want to re-discover our identity as luminous beings in the cosmos, we must first try to pinpoint our prejudices and discard them. Materialism is an obsolete philosophical dogma and modern scientists should try to also use other premises as the foundation of their theories to approach the mysteries of the self. Exact sciences need to examine the world with a more open mind, accepting potentially different interpretations of existing experimental data in the fields of brain research, which are currently not considered simply on the basis of a strong anti-spiritual dogmatism. Such interpretations can be compatible with the notion of an immaterial spirit proposed by religion for thousands of years. Mind seems that is not the by-product of matter, but the opposite: its master. No current materialistic theory can explain how matter may give rise to what we call “self” and only a drastic paradigm shift towards more idealistic theories will help us avoid rejecting our own nature.

Published at: International Journal of Theology, Philosophy and Science, Vol 2, No 2 (2018)

Spyridon_Kakos_Consciousness_and_the_EndDownload

The fallacy of Education as a Source of Ethics

Abstract: For centuries, the major story of enlightenment was that education is and should be the cornerstone of our society. We try to educate people to make them respectable members of society, something which we inherently relate to being “better persons”, firmly believing that education makes humans less prone to evil. Today, modern research seems to validate that premise: statistics verify that more education results to less crime. But is this picture accurate and does this mean anything regarding morality per se? This paper tries to examine the facts with a more critical eye and determine whether education is indeed a source of ethics or not. The results of the analysis show that what we understand as education is not only unrelated to ethics but can also be a factor resulting in the degradation of morality in humans. Rousseau’s arguments against science and arts are re-enforced with arguments stemming from other great philosophers and from modern experience itself. Using modern statistical analysis regarding the correlation of crime and education and through the examination of the modern regression in ethical issues, it becomes evident that education cannot and should not be a source of ethics. Knowing what is ethical is not as important as living an ethical life. Pharisees were the first to be denied the entrance to the kingdom of God. As Oscar Wilde once said, “Education is an admirable thing, but it is well to remember from time to time that nothing that is worth knowing can be taught”.

Published at: MCDSARE 3 33-41. 2019

The fallacy of Education as a Source of EthicsDownload

Against the realistic interpretation of the Theory of Relativity

Abstract: The Theory of Relativity has been portrayed as a theory that redefined the way we look at the cosmos, enabling us to unlock the reality we live in. Its proponents are constantly reminding us of how Einstein managed to reveal the true nature of the universe with his groundbreaking theory, which has been proved multiple times until now. Yet, philosophy of science teaches us that no theory has any privileged connection with what we call reality per se. The role of science is to formulate models of the cosmos we see and not to try to interpret or reveal reality. This paper tries to show how this holds true even for the famous relativity theory, by showing specific objections to the connection of the theory with the Holy Grail of philosophers. By analyzing various subjects related to the theory, from the twins’ paradox to the GPS satellites, this paper illustrates that relativity is much less connected to reality than what we would like to think. At the end, what Einstein’s theory provides is nothing more than a way to formalize the interactions of the world but without being able to make any claims whatsoever regarding the ‘reality’ of its conclusions.

Against the realistic interpretation of RelativityDownload

On the untrustworthiness of axiomatic-founded science

Abstract: The idea of science being the best – or the only – way to reach the truth about our cosmos has been a major belief of modern civilization. Yet, science has grown tall on fragile legs of clay. Every scientific theory uses axioms and assumptions that by definition cannot be proved. This poses a serious limitation to the use of science as a tool to find the truth. The only way to search for the latter is to redefine the former to its original glory. In the days well before Galileo and Newton, science and religion were not separated. They worked together to discover the truth and while the latter had God as its final destination, the former had God as its starting point. Science is based on the irrational (unproven) belief that the world is intelligible along many other assumptions. This poses a serious limitation to science that can only be overcome if we accept the irrationality of the cosmos. The motto “Credo quia absurdum” holds more truth than one can ever realize at first glance. There is nothing logical in logic, whereas there is deep wisdom in the irrational. For while the former tries to build castles on moving sand, the latter digs deep inside the depths of existence itself in order to build on the most concrete foundations that there can be: the cosmos itself. The only way forward is backwards. Backwards to a time when religion led the quest for knowledge by accepting what we cannot know, rather than trying to comprehend what we do not. Science was anyway based on that in the first place.

Published at: Harmonia Philosophica [link], Academia [link], PhilPapers [link]

On the untrustworthiness of axiomatic-founded scienceDownload

Philosophical dogmatism inhibiting the anti-Copernican interpretation of the Michelson Morley experiment

Abstract: From the beginning of time, humans believed they were the center of the universe. Such important beings could be nowhere else than at the very epicenter of existence, with all the other things revolving around them. Was this an arrogant position? Only time will tell. What is certain is that as some people were so certain of their significance, aeons later some other people became too confident in their unimportance. In such a context, the Earth quickly lost its privileged position at the center of the universe and along with this, the ideas of absolute motion and time became unbearable for the modern intellect, which saw nothing but relativeness in everything. After years of accepting the ideas of relativity at face value without doubting them, scientists are now mature enough to start questioning everything as any true scientist would do, including their own basic assumptions. And one would be surprised to see that the basic assumptions of today’s science in physics (and cosmology alike) are based on philosophically dogmatic beliefs that humans are nothing more than insignificant specks of dust. These specks cannot be in any privileged position in the cosmos, nor can their frames of reference. These specks cannot be living on a planet that is not moving while everything else is. There can be no hint of our importance whatsoever. Hence, the Copernican principle that has poisoned scientific thinking for aeons now. When one analyzes the evidence provided by science to support the idea of relativity though, he would see that the same evidence can more easily and simply fit into a model where the Earth stands still. Yet, scientists preferred to revamp all physics by introducing the totally unintuitive ides of relativity – including the absolute limit of the speed of light – than even admitting the possibility of humans having any notion of central position in the cosmos. True scientists though should examine all possible explanations, including those that do not fit their beliefs. To the dismay of so many modern scientists who blindly believe the validity of the theory of relativity at face value, the movement towards a true and honest post-modern science where all assumptions are questioned, necessarily passes through a place where the Earth we live in stands still. Non-relativistic explanations of the Michelson Morley experiment, related to a motionless Earth or to ether, are viable alternatives that deserve their place in modern scientific thought.

Published at: Harmonia Philosophica (here), Academia (here), PhilPapers (here), ResearchGate (here)

Philosophical dogmatism inhibiting the anti-Copernican interpretation of the Michelson-Morley experiment v0.6Download

Religion as the single foundation of Science

Abstract: For centuries, science was considered as something radically different from religion. Yet, the foundations of true science are deeply religious in nature. This paper seeks to show how religion is the only foundation needed for the formulation of scientific theories, since it provides the core principles on which the building of exact sciences is based upon. Our need to understand the cosmos and our faith in us being able to do so, are the main prerequisites for conducting science; prerequisites that are derived from our belief in us being the sons of God and, thus, being able to read His mind. From its birth on 7 March 1277 up to today, science seems to be the only logical attitude of religious people towards the unknown cosmos.

Published at: Academia (here), PhilPapers (here)

Religion-as-the-foundation-of-Science_v1.000Download

Against the Senses

Abstract: The validity of the senses we use to experience the cosmos is something we take for granted. The majority of the people view the senses as the most effective and potentially the only tool they have to reach reality. But as Shestov rightfully questioned, when was the last time the majority decided correctly on an important philosophical problem? The role of science and philosophy is to question the obvious and this is what we should do if we are to uncover the true role of the senses. This paper uses a series of philosophy articles to touch on the problem of the senses and the answer portrayed is exciting as well as terrifying: The senses are not a helpful tool but more of a hurdle when it comes to understanding the cosmos…

Published at: PhilPapers (here), Academia (here)

Humans in the meta-human era (Meta-philosophical analysis)

Harmonia Philosophica papers
December, 2023

Abstract: Humans are obsolete. In the post-ChatGPT era, artificial intelligence systems have replaced us in the last sectors of life that we thought were our personal kingdom. Yet, humans still have a place in this life. But they can find it only if they forget all those things that we believe make us unique. Only if we go back to doing nothing, can we truly be alive and meet our Self. Only if we stop thinking can we accept the Cosmos as it is and know what Being is. Only if we become irrational can we ever understand what AI will never understand. Humans need to destroy what they have created, because in the world they have built they have no place. Unless we become children once more. And laugh for no reason. In a cosmos that was meant to be our home.

Humans in the meta-human era (Meta-philosophical analysis)

Published at:

Humans-in-the-meta-human-era-v1.00Download

Advanced Materials: Use of Polypyrrole in Printed Circuit Boards (PCB)

The objective of our work is to investigate the application of polypyrrole (PPy) as a conductive precoat for the metallization of PCB holes. The method includes: etching of FR4, in situ deposition of a thin film of PPy, resulting in a FR4/PPy electrode. The process is very promising and environmentally friendly compared to the conventional electroless one. Several variables of the process at a laboratory level were studied. The poylyrrole-modified FR4 surfaces were conductive enough to allow the copper plating of the specimens at a later stage. Moreover, the peel strength of the copper plated on FR4 with our method was adequate.

 Paper Key Facts

  • Written in the context of the research conducted for my phD thesis in “Advanced Materials” at National Technical University of Athens.
  • The goal of our team is to develop a new innovative and more environment-friendly method for the PCB through-hole plating stage with the use of Polypyrrle conductive polymer.
  • Based on a paper posted at 1st WSEAS International Conference on Materials Science, Bucharest, 2008 under the title “Polypyrrole-based metallization of insulators – An application to Printed Circuit Boards (PCB)” with C.D. Yfantis and D.K. Yfantis as co-authors. Additional material is being added continuously.
  • The author Spiros Kakos is a member of Professor’s D.K. Yfantis team at the Chemical Engineering school, Materials’ Sector of NTUA (Athens, Greece).

1  Introduction

Conducting polymers (CPs) were first produced in the mid-1970s [1] as a novel generation of organic materials that have both electrical and optical properties similar to those of metals and inorganic semiconductors, but which also exhibit the attractive properties associated with conventional polymers, such as ease of synthesis and flexibility in processing.

Polypyrrole (PPy) is one of the most widely used conductive polymers, due to its high chemical and physical stability, low toxicity of the monomer and its easy chemical or electrochemical synthesis, even in aqueous solutions [2] [3] [4]. PPy may be prepared by chemical or electrochemical oxidation. It has been proven that by inserting doping anions (Figure 1) like PTS (para-toluene-sulfonic acid) the conductivity of PPy can be increased up to 102 S/cm. [5] [6] [7].

Figure 1 – Doping mechanism of PPy

Applications of PPy were essentially extended during last years and include now such different fields of science and technology as corrosion protection of metals, development of individual electronic devices e.g. diodes, metallization, electromagnetic interference shielding, biosensors, tissue engineering scaffolds, neural probes, drug-delivery devices, and bio-actuators [8] [9] [10].

2  Problem Formulation

In microelectronics, printed circuit boards (PCBs), are used to mechanically support and electrically connect electronic components using conductive pathways, or traces, etched from copper sheets laminated onto a non-conductive blank fiberglass substrate (“the board”). There are many types PCB substrate material, but by far the most common is a standard woven epoxy glass material known as FR4.

The complexity of PCBs, vary from single-sided boards, where circuitry is found on only one side, to double-sided boards, to boards comprising several layers of circuitry. Connections between the two sides of a board and layer-to-layer connections are made with copper-plated through-holes (PTHs) [8].

Figure 2 – PCB through-hole copper plating with PPy used as a precoat (pretreatment)

The through-holes are drilled into the laminated substrate and are then copper-plated (Figure 2).

The introduction of double-sided, followed by multilayer boards, was achieved by metallization of the drilled holes with electroless copper. Autocatalytic electroless copper plating has been successfully used for over 30 years. However, this process has certain disadvantages [11].

Firstly, electroless deposition of copper requires a reducing agent. Formaldehyde, the most commonly used reducing agent in electroless baths is toxic and poses environmental concerns. Secondly, electroless baths are generally unstable and require close monitoring. Control becomes a problem and cyanide and chelating agents have to be added, which in turn are difficult to remove from waste streams [11].

In addition to the environmental concerns about electroless copper metallization, circuit board manufacture using this process requires the use of expensive noble-metal salts, such as PdCl2 and as many as 8- 10 steps (including rinses).The inherent disadvantages of the electroless copper metallization fostered interest in direct metallization of copper. There are processes in which the activation of the non-conducting wall of the PCB holes is effected by deposition of carbon particles or conductive polymers [11] [12].

3  Problem Solution

The aim of the present study is to investigate the application of polypyrrole (PPy) as a conductive in situ precoat for the metallization of PCB holes.

Several variables of the process at a laboratory level were studied.

In particular, the effect of the substrate pre-treatment (H2SO4)and the polymerization bath synthesis (addition of ΚΟΗ) on the peel strength of copper on the FR4/polypyrrole electrode was evaluated. An assessment of the peel strength of the copper plating was performed. Furthermore, the interface and the thickness of the copper electrodeposited was studied by SEM/EDS analysis.

3.1 Materials and Methods

Firstly, FR4 specimens (2,5 x 2,5 cm)  were etched by immersion for 30 min in a firmly agitated aqueous solution containing 8% pv (NH4)2S2O8. Ammonium persulfate acts as an oxidant in the polymerization of pyrrole. PPy is polymerized on FR4 surface, from an appropriate optimized solution that contains 3.6% pv pyrrole and 4.4% pv. PTS that acts as a dopant [10]. Thus, a new electrode is formed that can be electroplated.

The FR4/PPy electrode has been electroplated using the electrolytic cell that contained a copper ion bath. The composition of the copper deposition bath was:150 g/L CuSO4*5H2O, 50 g/L H2SO4, 50 g/L CH3CH2ΟΗ (EtOH). Copper was deposited onto FR4/PPy surface resulting in the formation of a FR4/PPy/Cu sample. After being covered with PPy film, FR4 specimens were immersed in AgNO3 0,1 N solution for 10 min before metallization started.

During the copper electrodeposition of FR4 substrates the current density and the metallization time were recorded.

The peel strength of copper coating (Cu) on the polypyrrole-modified FR4, was measured according to ASTM-B-193-02 specification. SEM/EDS analysis of the copper coated FR4 specimens was performed.

3.2 Results – Discussion

3.2.1 Through hole plating with polypyrrole

The results of our experiments show that the use of polypyrrole can lead to sufficiently conductive holes to allow their metallization at a later stage. We have used spraying as well as immersion techniques for the in situ polymerization of pyrrole into polypyrrole at the hole walls.

PCB copper plated holes with the use of polypyrrole [Immersion technique] {Z1A Experiment}

From the experiments conducted it seems that the use of spraying technique does not allow the full metallization of holes, especially in cases of PCB with more than 10 inner layers. Immersion technique looks like the only viable solution for such metallizations.

Micro-intersection analysis at 16-layer PCB in which the holes were metallized with the polypyrrole-based method of our team, has shown good copper plating results as shown in the next schema.

Micro-intersection analysis (x200) at copper plated hole walls of 16-layer PCB

The results show that the copper plating resulting from the use of polypyrrole as pre-coat has good quality and satisfactory continuity with the inner-layer copper.

3.2.2 Attempts to increase the peel strength

In a previous work we have tested the adhesion of copper layer on ABS specimens according to the ASTM D 3359, method B (“Cross-Cut Tape Test”) [2]. It has been demonstrated that the peeling of the copper coating is caused by the poor adhesion of the PPy film on ABS [12].

For this reason, we attempted to increase the peel strength of PPy on the FR4 substrate by (a) chemical treatment (etching) of the specimens with H2SO4 and (b) addition of KOH in polymerization solution.

A. Treatment with H2SO4

Figure 3 shows the peel strength (lb/in) as a function of etching time (min).

Figure 3 – Peel strength of copper on FR4 (lb/in) vs. etching time (min)

Peel strength of 0.90 lb/in was reached after pre-treatment with sulfuric acid for 3 minutes (Figure 3). Therefore, the etching of the substrate with H2SO4 has significantly increased the peel strength.This can be attributed to the poor acid resistance of epoxy resins that results in an increase of the surface roughness.

B. Addition of  KOH to the polymerization solution

Adding dropwise 6% w/v KOH to the polymerization solution results in a significant increase of the peel strength from 0.29 lb/in to 0.35 lb/in.

SEM/EDS analysis of two groups of polypyrrole-modified FR4 copper plated specimens: Group A: without KOH addition and Group B: with KOH addition

Figure 4 – Group A specimen (representative cross-section view)

The polypyrrole conductive layer (interface) was not of equal thickness and ranged from 4.5 μm to 9.65 μm (Figure 4). Additionally, in figure 5, EDS analysis of a Group A specimen is shown.

Figure 5 – EDS analysis of a Group A specimen

Figure 6 – Group B specimen (representative cross-section view)

As it is shown figure 6, the PPy layer was more uniform with a thickness equal to 1.88 μm. The EDS analysis of the specific specimen is demonstrated in figure 7.

Figure 7 – EDS analysis of a Group B specimen

EDS analysis results (Figures 5 and 7) clearly demonstrate that the addition of KOH reduces the mass of Cu deposition. This finding is in agreement with the reduced Cu film thickness deposited on  Group B specimen as revealed by SEM.

4. Conclusions

Within the limitations of this study, the following conclusions can be drawn:

  • The FR4/PPy electrode has sufficient conductivity to allow the copper plating of holes (through-hole plating)
  • Using H2SO4 as an etching agent increases the peel strength of the copper coating on the substrate up to 0.90 lb/in. This may be attributed to the roughness increase of the FR4 surface.
  • The addition of KOH to the polymerization solution also increased the peel strength of copper on FR4. However, it reduced the mass of deposited Cu.
Exit mobile version
%%footer%%