On April 25, ACB organized their technology seminar….Eyes on the future, feet on the ground…

ACB, known in Europe as leading manufacturer of High Technology & Quick Turnaround Printed Circuit Boards, organized its first technology seminar.

The brand new CEO, Gilles Rigon, opened he seminar with explaining all about the ACB philosophy. “S” for simple and easy solutions where possible, “S” for souple and flexible processes and “S” for Solid and reliable processes and how they balance their “eyes on the future” with their “feet on the ground” approach. In fact, the importance of this balance would return in many lectures coming.

Arnaud Grivon, PCB/PCBA Technology expert from Thales showed us the possibilities and limits from stacked filled microvias and how design has a major impact on their reliability. This technology is required to make routing possible for fine pitch BGA or array components (pitch < 0.5 mm) using microvia-in-pad and filled stacked vias. The Cu filling is not only creating a smooth surface for assembly but can increase the reliability of the microvia too, as long as it is properly filled. Tests have proven that the aspect ratio is max 0.8. This means that microvias can only be filled completely in a thin insulation-layer. This sounds logic but this technology is highly sensitive and requires strict process control.

This brings us to the following presentation. Wim Perdu, CTO at ACB, spoke about the sense and nonsense of IPC requirements in design, process and inspection. For high density boards and fine pitch design, the feasibility of some requirements in IPC class 3 or class 3A is doubtful and not always relevant for better or more reliable quality, and the cost related with the required inspections is hallucinatory. He expressed what many of us think but don’t dare to say because we don’t want to awake sleeping dogs. Instead of attacking IPC standards, we try to set up workable methods to control our processes. We set up mechanisms to avoid failures instead of detecting them in a final product. And, indeed it is more important to know the capabilities of your supplier then to “overspecify” the products, since many aspects are hardly possible to inspect in a finished product and like Wim said: The reality is simple: if it is offered for free, it is not done.

The next presentation came from Jan Vanfleteren who is developing for IMEC- UGent/CMST flexible and stretchable circuits. There is an increasing demand for portable, wearable and implantable electronics and sensor systems. To achieve the needs for comfort, place and weight saving CMST developed a technology to integrate flexible ultra thin chip packages in stretchable circuits which are completely embedded in order to make them washable and implantable. This technology tries to make use of the existing standard PCB processes and uses temporary layers for support during processing. These support layers are removed later on and the result is complete embedding in elastic materials. Although this is an example of the “eyes on the future” aspect, we saw more than 1 realization of stretchable, dynamically deformable or integration in textile. The challenge now is to have these products developed and produced on an industrial scale.

Back to the essence now: Wim Huwel, NPI Engineer at ACB, convinced the attendees about the importance of the DFM (design for manufacturing). It implies an early cooperation between designer and PCB manufacturer. It combines tools and techniques to achieve better quality in a shorter development time and a more mature product at a lower cost. Early involvement makes it possible to guide designers to use the correct industrial design rules and chose the best material for their application. It also avoids creating the need of extra ordinary process capabilities. Use the design rules and keep it as simple as possible. He showed us many examples of how almost impossible build-ups were altered to the ACB “standard constructions”
= > For this reason, we, at Eurocircuits send out all these (sometimes annoying) remarks and exceptions. We share the same opinion: use the design guide lines, check the classification table and keep it simple!

Geert Willems, driving force behind the EDM-projects, at his turn continued with an exposé about via reliability. Too difficult to follow for most of us but he showed the need of physical models to understand the parameters that influence the reliability of vias such as via diameter, PCB thickness, the CTEz of the material and the Cu deposit with their degree of importance. He announced that all conclusions will be included in the new DfM Guideline coming soon.
=> As EDM-partner of the early hour Eurocircuits sat down with Geert on this subject some years ago. Based upon his reliability model, we defined the basic material parameters for the base material used in our pooling services. This lead to a better quality of lead free boards and zero material defects during the last 3 years.

Wim Christiaens, NPI Engineer at ACB, returned to the subject of stacked and filled micro-vias and the importance of well filling. He guided us through the challenges of the projects they set up to achieve this properly filled micro-via. He used different BGA configurations to explain the use and the importance of the µBGA design rule table and the relation with the PCB class. If you ever have the need for this technology, you should consider his involvement at an early stage. His explanation of this rather difficult subject was very clear!

The row of presentations was closed with a lecture from Johan De Baets, from IMEC-CMST about Embedded components in printed circuit boards. Traditional printed circuit boards have components on top and/or bottom. Embedded technology started around 1990 with printed resistors and capacitors to arrive at the current stage where silicon and chip become embedded in the PCB. During the last 15 years several methods were developed to embed active components too. Johan introduced the HERMES project: High density integration by Embedded chips for Reduced size and Electronic Systems. To be able to combine and optimize all the available existing technology from design, PCB, PBA and silicon dies many industrial players are working together in this project. It requires a complete new business model to make this project possible.

The event was held in the Verbeke foundations residence and proved to be a perfect location for contemporary art and technology crossover.