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Dow’s MICROFILL EVF process has been used in high volume manufacturing (HVM) in more than 100 lines over the last 10 years. This new generation EVF15 is already being used at multiple sites, as demanded by leading-edge customers who need the ability to create finer lines and features with a higher yield. Hemeixinpcb is committed to continuing the pioneering tradition of plating innovation, and we continue to work on our pipeline of new products to meet the needs of the leading-edge HDI PCB manufacturers.

Customers should be aware of the prices and construction methods involved for HDI PCB before deciding to use smaller pitch parts that require the use of HDI PCB and μVias. As HDI PCBs increase in complexity, cost increases range from 20% to 80%, depending upon the processes involved. The primary cost factors with HDI PCB are due to the additional drilling, plating, and laminating processes and the materials used for plating and filling the μVias. The total number of μVias is fairly insignificant; the process is the same for just a few holes as it is for a large number of holes. Below are shown ballpark increases in cost for some of the additional processes.

Board Cost: My engineer’s original cost target was approximately $14 per board. Fab quotes for the original 20-layer design actually came closer to $18 per board. When we settled on the smaller form factor and the 16-layer stack-up, the per-board cost of the HDI PCB design dropped to $15, a savings of about 17% from the original 20-layer estimate. This was primarily due to the increase in the number of boards per panel (twice as many as the larger original size), as well as the reduced layer count. Obviously, not all HDI PCB designs are going to have such a positive cost impact. Although HDI PCB is typically more expensive, it should not be assumed to always be so. With so many variables in play, all of the cost factors should be evaluated before a decision is made either for or against HDI PCB.

Cost factors: (rules of thumb)

10-20 layers, add 10-20% per add’l layer pair

(above 20 layers costs climb even higher)

Non-conductive via fill +20%

Via-in-Pad filled and planarized +25%

One-layer deep μVia -5%

As mentioned above, the fabrication process for HDI PCB and μVia construction is more expensive than conventional thru-hole processing. Each successive μVia layer pair adds a lamination cycle to the construction process and, therefore, additional costs.

Hemeixinpcb has been a leader in HDI interconnect innovation and mass production for over fifteen years. All of our factories have mass production capacity for microvia-based HDI PCB processing, combined with fine line copper trace formation by semi-additive or subtractive copper plating. Complementing a variety of multilayer HDI PCB fabrication process flows is an extensive capability for final surface finishes that support the lead-free attachment of SMT components. HDI PCB is characterized by high-density attributes including laser microvias, fine lines, and high-performance thin materials. This increased density enables more functions per unit area. Higher technology HDI PCB has multiple layers of copper filled stacked microvias (Advanced HDI PCB) which creates a structure that enables even more complex interconnections. These very complex structures provide the necessary routing solutions for today’s large pin-count chips utilized in mobile devices and other high technology products. The original concept relied on sequential layer lamination atop a first double-sided fine line HDI PCB core. Innovations in laser via formation, copper plating chemistries, process tools, direct imaging of resists and solder mask materials, and layer registration techniques have been continually refined and improved to build a state-of-the-art mass production facility in China.

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