05-22-2023

A thick, high layer count multilayer is one of the hardest printed circuit boards to adapt to lead-free assembly processes. The reason: Multilayers often have through-hole and hand-soldered components and require two or more rework cycles. The higher reflow temperatures and slower wetting of lead-free solders place an enormous strain on the laminate and copper-plated hole barrel. In many cases, the boards cannot be assembled reliably, even with newer, higher thermal performance FR-4s.

03-28-2023

In last month's column, this author framed up the initial challenges for the PWB fabricator to be successful in producing IC substrates to support advanced packaging. In this month’s feature, the author will explore two more areas of processing that fabricators need to master: Imaging/developing, and etching.

03-07-2023

There has been much written and discussed over the last 18 months relating to semiconductor fabrication and the well-founded concerns that the U.S., in particular, has fallen behind in domestic chip manufacturing. In response to this issue, the United States government has enacted the CHIPS for America Act. Funding under this legislation is designed to drive more chip fabrication domestically. While this is all fine and good, once these advanced chips are manufactured, where will they go? As has been said ad nauseum, “Chips don’t float.”

01-09-2023

As circuits become more compact, circuit lines and the spaces between them are becoming finer. As the distances between these lines decrease, copper over-plating is more likely to have a deleterious effect on photoresist stripping, which can lead to shorts on costly fine-line PCBs. PCB designers, for example, must attempt to squeeze increasingly more amounts of information onto a smaller board. In practical terms, this means that circuits are becoming more compact; circuit lines and the spaces between them are becoming finer. As the distances between these lines decrease, copper overplating is more likely to have a deleterious effect on photoresist stripping.

11-09-2022

The photolithography process defines the circuitry on the panel. As one may surmise, the imaging process used in the fabrication of high density and ultra high-density circuity has made significant advances over the last decade—and just in time. With finer lines and spaces as well as more attention to fabrication of printed wiring advanced packaging substrates. However, as is so true of many of the processes in PWB fabrication, up and down stream processes can and will influence what happens in a particular process.

10-06-2022

Success in the plating room rests largely on the understanding of and the application of those critical principles that govern the process of electrodeposition, or electroplating as it is often referred. This month, I look at the fundamentals of plating distribution and throwing power, and what that means for the circuit board fabricator. There are many factors that influence the flow of current in the electroplating cell and ultimately the distribution of the metal across the part along with the concept of throwing power.

08-15-2022

If one thought that electroless copper and other metallization systems were complex and the deep dark secrets of these systems shrouded in black magic, the discussions on electroplating will seem like brain surgery. In this next series of columns, the intricacies of electrodeposition technology and its function of building up the thickness of copper in the holes and on the surface will be presented in detail. Function of the active ingredients in the copper plating solutions will be presented. Process control limits for the various plating solution components and the effects on deposit integrity will be discussed.

03-04-2022

Electroplating a printed circuit board is by no means a trivial task. Higher layer counts, smaller diameter vias (through-hole and blind), as well as higher performance material sets contribute to the greater degree of difficulty with today’s technology. So, process engineers pay close attention to the “softer” issues such as cathode current density, solution chemistry (copper sulfate and sulfuric acid concentration), and—sometimes—addition agent control.

02-28-2022

It seems the operative word today is additive circuit board manufacturing, or for that matter, additive for everything. It is true that the use of additive manufacturing technology has found its way into different industries. While there may be several advantages to adopting additive technology in various industries, one should take a step back and truly assess where we are today in relation to conventional and advanced printed circuit board technology. It makes sense to understand the differences between fully additive, semi-additive, modified semi-additive (mSAP) and subtractive. In the end there are a number of options available to the fabricator and OEM to achieve high density and ultra-density circuitry to support higher end technologies including IC substrates.

02-02-2022

The photoimaging process is one of the first steps in the PCB fabrication process. In order to ensure that the image of the circuitry conforms as close to the desired design as possible (i.e. lines and spaces), surface preparation of the copper foil surface is one of the most critical success factors. Employing the optimum mix of surface cleaners and microetchants will provide a clean surface with sufficient surface area to promote dry film adhesion. The fabricator has numerous options and should determine the optimum process by accounting for the type of copper foil used as well as the classes of soils to be removed. More on copper foil types in a future column.

12-27-2021

One of the most difficult things about trouble shooting PCB defects is getting to and understanding the root cause of defects. Many of these defects have can have multiple origins. And many may not manifest themselves in the process where the defect occurred. Thus are the perils of jumping to conclusion about the defect. Often this author gets involved in solving technical issues and the engineer at the board fabricator or OEM calls the defect an anomaly. Not really a good idea to go off trivializing the “purported anomaly.” Failure to understand the true genesis of the defect will lead to incorrect remedies to these issues. We will now present some of these defects and the possible remedies.

10-25-2021

In a previous column, the author presented several options with which to accomplish blind and through-hole via filling. In this edition of “Trouble in Your Tank,” filling blind and through holes with polymeric pastes will be presented.

10-07-2021

For this month’s edition, we are taking a slightly different approach—that of presenting an actual case study. However, the basic principles of these columns continue.

08-24-2021

Regardless of the industry where one competes, there is constant pressure to develop new products and penetrate new markets. This difficulty is heightened when your company is situated in a high-technology industry such as electronics, which requires continuous investment in equipment, infrastructure, processes and, of course, skilled workers.

08-13-2021

Columnist Michael Carano speaks frankly about the current state of price increases in the PCB industry, and what needs to change to stay alive.

05-27-2021

Columnists were asked to consider subjects such as optimizing business processes and strategy, process optimization, and training your team. From my view, developing critical thinking skills will help engineers troubleshoot technical issues and bring the issue to quick resolution, as this is certainly a good lead in to training your team.

04-26-2021

One of the most difficult things about trouble shooting PCB defects is getting to and understanding the root cause of defects. Many of these defects have can have multiple origins. And many may not manifest themselves in the process where the defect actually occurred.

03-29-2021

Troubleshooting process related defects is not as simple an exercise as we would like to believe. The printed wiring board fabrication process is a complex set of mechanical and chemical processes containing multiple steps. When even one of the process steps is not in control, end results can be disastrous. For now, the author presents a view of some defects that at first glance the origins are not obvious.

02-19-2021

Minimizing defects and improving yields is especially important as the technology is becoming ever so complicated, and additional focus must be placed on yield improvements. This is where process management and control must be front and center.

01-21-2021

While troubleshooting everyday processing issues, final etching touches on many downstream processes. These include surface preparation, imaging, and copper surface quality. There are concerns with the etching process itself and how process issues and operating parameters impact the circuit formation quality. In this month’s edition of “Trouble in Your Tank,” the subject of etch-outs, undercut, and linewidth reduction will be presented.

12-30-2020

In last month’s column, Michael Carano presented various etching defect causes related to equipment parameters. In this month’s column, he discusses various other causes that lead to etching defects.

11-20-2020

Sure, etching of copper foil has been in existence since before through-holes were mechanically drilled. However, as circuit density has evolved into finer and finer lines and spaces, the mechanical and chemical aspects of etching copper have evolved as well. Michael Carano provides an overview of the inner layer and outer layer etching process, including chemical and mechanical aspects of the process, different chemical formulations involved, and other unique aspects of each.

10-23-2020

One cannot underestimate the importance of surface preparation of the copper surface and its relationship to dry film adhesion. Michael Carano explains why chemical cleaning methods are favored over mechanical methods as long as copper removal rates are reduced and excessive surface roughness is avoided.

09-29-2020

For those associated with PCB fabrication, one of the biggest nightmares is often the infamous interconnect defect (ICD). Essentially, an ICD is a separation of the plating from the interconnect foil. In this column, Mike focuses on Type 1 ICD and D-sep.

08-29-2020

Mike Carano highlights electroless copper plating solutions, focusing on a copper formulation based on copper chloride, EDTA, formaldehyde, and sodium hydroxide.

08-11-2020

In Mike Carano's words, "In my April 2020 column in PCB007 Magazine, I incorrectly misrepresented the origins and causes of conductive anode filament (CAF) formation. This follow-up column will provide more insight and depth of knowledge on the CAF failure mode."

07-31-2020

Michael Carano discusses two interesting technical problems: the case of circuit open or etch-out, which will also include circuit width reduction related to undercut, and a defect that relates to extraneous copper remaining on the board. Both issues illustrate the complex nature of PWB troubleshooting and defect analysis.

06-15-2020

Defects may “manifest” or be detected in or after a specific operation within the PCB manufacturing process, but the underlying root cause may have occurred earlier in the process. In this column, Mike Carano focuses on several anomalies that may have their origins in process steps not normally recognized as the root cause of the issue.

05-15-2020

There are many reasons to get incredibly frustrated and confused when presented with complex issues related to the PCB fabrication process. Mike Carano reviews the concerns with the possibility of multilayer board delamination and the root cause or causes of the defect.

04-30-2020

Mike Carano explains how there are two additional concerns fabricators must understand and reconcile as the circuit technology continues on the high-density curve along with the plethora of new materials to meet the technological demands: conductive anode filament (CAF) formation and wicking.

12-15-2019

Michael Carano's father always said to him, "You should never stop learning," even when he was 40 years old. This lesson applies to the PCB manufacturing industry as well and is where constant learning and new skills development come into play. Mike introduces a few new things you can learn, both technical and soft skills.

12-12-2019

One does not have to look too far back to point out some significant changes that have taken place in our industry over the past few years. Processes, materials, equipment, and board designs continue to change. If I were to pick one to focus on for this column, it would be in the ever-increasing trends toward higher circuit density. This relates to finer lines and spaces, smaller diameter blind vias, and even multilevel stacked and staggered vias. All of these changes will continue to place significant pressures on bare PCB fabricators to increase their investment and onboard new and critical skill sets.

11-15-2019

In my previous column, I presented several options with which to accomplish blind and through-hole via filling. In this edition of “Trouble in Your Tank,” I will discuss filling blind vias and through-holes with polymeric pastes.

10-24-2019

Even though they are a smaller part of the circuit board industry, flex and rigid-flex circuits have been growing in popularity over the last decade, and for good reasons. These circuits are made to be thin, flexible, and durable. However, in addition to the opportunities that come with flex and rigid-flex circuits, there are also challenges. Find out more here.

09-11-2019

High-density interconnect (HDI) demands that vias that do not contain component leads be plugged with either a polymeric paste or electroplated copper. In this column series, Michael Carano talks about the technology drivers for via filling/plugging in the context of HDI.

08-06-2019

Copper deposit in the vias with electroless copper or alternatives, such as carbon-based direct plate processes to the vias, depends on process control, equipment design, and chemical parameters. When these are not in control, defects arise. In this installment of the column series, Mike Carano will talk about metallization for HDI blind via processing.

05-09-2019

Two often overlooked performance attributes for organic solderability preservatives (OSPs) are the organic film thickness and the topography of the copper after microetch. Film thickness up to an extent is critical. However, the copper topography and surface preparation also play a role. Thus, you should not overlook the critical nature of the overall OSP film thickness. Read on.

03-20-2019

If we have learned anything about moving into HDI manufacturing, it is that it takes a great deal of thought and discipline to be successful. Unfortunately, as the following bullet points delineate, all too often, the fabricator underestimates the scope of HDI and what this manufacturing strategy truly entails.

02-28-2019

Surface preparation and cleaning are essential aspects of metal finishing and PCB fabrication. The PCB fabricator has several processes that fit the broad category of cleaning and surface preparation. However, the organization needs additional studies to enhance the broad portfolio of products for their respective fitness for use in today’s technology.

02-12-2019

Yes, there is some art to the resist stripping operation. However, it is more about the science. In a future column, I will present process control methods for resist stripping as well as dive into additional troublesome activities related to the process.