What to consider for your next HDI PCB
In an environment where time-to-market is everything, the manufacturing of bare PCBs, especially high-technology ones (eg. High-Density Interconnect PCBs), plays an important part in the overall time cycle. By the time engineers have a PCB design, their project is often running behind schedule. So, when they come to us with urgent requirements, the last thing they want to hear is that the design cannot be manufactured in its current state causing further delays.
It doesn’t matter how innovative or great a new product is, if it doesn’t get to market before someone else’s, then it becomes an expensive and futile exercise. A slow speed to market virtually hands the competitive advantage to your competition. By the time our customers come to us, we virtually feel like we are selling time, not PCBs or PCBAs.
There are three important factors to consider when selecting a quick-turn PCB manufacturer to partner with. They are:
Technical knowledge, and
Reputation (especially for delivering quality boards on-time)
Unfortunately, local manufacturing of High-Density Interconnect (HDI) PCBs is not available to Australian or New Zealand OEMs, so Technical Knowledge and Reputation are the two main things to consider.
HDI boards, one of the fastest growing technologies in PCBs, contain blind and/or buried vias and often contain microvias. As they have a higher circuitry density than traditional circuit boards, these high-tech boards have finer lines, tighter spaces and annular rings. They also often require controlled impedance.
Stack ups for HDI boards often have different characteristics than standard technology boards. Most of the HDI boards we manufacture make use of blind (laser) and/or buried vias, which unlike normal vias do not go through the whole PCB. Blind vias go through from the outer-layer to an inner-layer whilst buried vias make connection from one internal layer to another internal layer. See image below of a sample 12-layer HDI board.
If the blind vias are located in a pad where the surface has to be flat and the soldering is critical, then either a copper or epoxy filling followed by a copper capping will provide a flatter surface than just using a copper filling, which can cause a dimple in the pad.
By making use of these types of vias, the size of a PCB can be significantly reduced to suit any specific purpose where space might be limited. Successful manufacturing of such high-tech boards requires specialised equipment and processes such as laser drills, plugging, laser direct imaging and sequential lamination capabilities.
Speak to one of our Account Managers before designing your next HDI board. We will review your stack up and check whether it requires controlled or not, and suggest various base materials that are easily available.