July 17, 2015

HDI stands for High Density Interconnect. It is the process of leveraging manufacturing capabilities and materials to create very small interconnect solutions. Small interconnects are required for some of the new applications and dense components on the market.

PFC is committed to HDI and has invested R&D dollars and resources to improving and providing HDI solutions to the market.

HDI flex requires the flex circuit vendor to design, manufacture and assemble – this is what we provide.

HDI applications

bandaidWearable technology is one of the new applications we are seeing – where dense packaging is required. Imagine wearing a sensor device that can monitor all of your vitals and connect to the internet via blue tooth so you doctor can monitor you remotely. The solution has to be bendable, stretchable, and dense. We will talk more about this in upcoming newsletters, but this is the type of application that drives density.

HDI lines, spaces and hole sizes

PFC has been providing 50 micron (2mil) lines and spaces in production for the last 6 years. Today, we have produced 37.5 microns (1.75 mils) line and space in prototypes quantities.

As you may recall, PFC has just acquired a new laser drill – the ESI 5335. The laser drill allows PFC to drill smaller holes (50 micron hole diameters). It also allows PFC to provide blind and buried vias for even denser packaging.

HDI materials

Very thin copper materials are essential to creating high density solutions. 9 micron copper is what is used in many cases to create HDI solutions. PFC is now evaluating/qualifying even thinner materials.

Benefits of HDI

  • Higher Density and smaller size
  • Use advanced component packaging
  • More design options and flexibility
  • Improved electrical performance and signal integrity
  • Improved thermal performance and reliability

HDI assembly

Many industry flex circuit gurus discuss HDI in regards to the density of the package – the circuit itself. However, in addition to the package, an HDI flex requires HDI assembly. PFC has been assembling flex for more than 10 years in house. Approximately 80% of PFC’s customers now receive an assembled flex circuit.

For HDI, PFC has been placing 1005 components for more than 18 months and has the ability to place 12 mil pitch BGAs. These are requirements for HDI – key components for the wearable market, for example require this assembly density.

PFC’s HDI Capabilities
Minimum drilled via finished diameter .004″
Minimum laser via formed diameter .001″
Minimum line and spacing .002″/.002″
Minimum copper thickness 9 micron
Maximum copper thickness <1 oz
Minimum pad size for thru-hole vias Via diameter +.005”
Minimum pad size for micro vias Via diameter +.005”
Panel size 18” by 24”
Thru hole plating aspect ratio 10:1
Blind micro via minimum plating aspect ratio 1:1
Panel plating Yes
Selective plating(pads only or button plating) Yes
Number of layers 2-16
Via fill Nonconductive Fill
Component Placement capabilities 1005
BGA Placement Capability 12 mil
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