The Tech Blog

There is an old xkcd comic I like to refer to when people talk to me about industry standards. Everyone seems to be on a separate bandwagon and eventually, some trigger point occurs in that domain and one standard will win out based on market forces. It may not be the greatest standard but it’s the one which is the most popular. This week I got introduced to a new communication standard called the DECT NR+(New Radio+) which is based on DECT-2020 released as part of 5G. It has a few interesting things going for it to spike my interest. Let me explain.

It’s a non-cellular standard(unlike NB-IoT and LTE-M), meaning you don’t need it to talk to mobile towers(So no need for subscription charges, similar to BLE, LoRa). There are no licensing headaches and charges, as it’s on an unlicensed spectrum range of 1.9GHz which is free to operate worldwide(Except India and China). Its meant to cater to Ultra-Reliable Low Latency Communication (URLLC) market with a latency spec of 1ms which is pretty great. Reliability is the key term here, they want this standard to be a replacement for a wired system. Ask any engineer they would still prefer wired solutions like ethernet for mission-critical data communication. NR+ is supposed to be the wireless equivalent of that.

NR+ can do high data rates of communication (Think WiFi) which will ensure that high bandwidth use cases are taken care of. Caters to massive Machine Type Communication (mMTC) type of use cases like self-driving cars on the road, low-power sensor networks, and smart meters. It can support upto a 1mn nodes in 1sq km, which is also huge. It has a large range claiming to be at around 1-2km on open fields. Has a self-healing mesh in which if one node fails in the network, data can be rerouted through some other node to reach its destination.

Well for internet connectivity for NR+ mesh, you would still need an edge device communicating to the internet. This standard is still in the early stages and will potentially hit commercial products in the next couple of years. There seems to lot of good stuff going for this standard, but will it win out? Only time will tell. If you need to learn more about this I would suggest reading the ETSI standard ETSI TS 103 636-1 for the full specs and checking out a webinar from NordicSemi on this for an overview of the tech. NordicSemi seems to be heavily invested in this as the next big thing.

It’s a relatively new PCB manufacturing tech on the market. It is used in ultra-high density PCBs that have a very high premium on space. To understand SAP, first you need to understand the traditional PCB manufacturing process. In a simplified overview, a traditional PCB is made by taking a substrate with Copper already present on it, then you do pattern masking based on the Gerber files that your PCB software provides and then you do chemical etching to remove copper in all areas where PCB tracks and lines are not needed. It’s a subtractive process.

Now the problem with this tech is that since Copper layers are relatively thick, etching away Cu can limit the thickness of the lines. You cant usually go below 3-4mil in thickness of tracks, if you do go thinner, you have the risk of Cu tracks being totally etched away and the track can be broken at places. For very high-density PCBs, designers would want to go below the 3-4mil limit(Think about high pad count BGAs) that’s where SAP shines.

In SAP, rather than taking board with Cu already on it, they start with a substrate. They add pattern masking and do something called as deposit Cu Electroless process. That’s just a fancy way of telling that Cu is deposited on a surface chemically(Not using electricity like electroplating). The advantage of this is that you can create a very thin uniform layer of Cu. Now if you need to remove some parts of Cu so readily do that because your Cu layer is very thin and removes easily. With this tech, you can potentially go to PCB track widths of 1mil(25um) or below.

Since the conventional etching process is not there, you get straight sidewalls(Think in 3D of a PCB trace) with much finer impedance control for those PCB traces(Usual processes may create trapezoidal sidewalls due to over-etching and a has +-10% impedance variation on tracks). This tech is being used by Apple and Samsung in their designs in last 3-4years to make their circuit boards smaller and reduce the layer counts on the PCB. They use something called modified SAP (mSAP) which is a mix of traditional and the new SAP tech(It’s too big to be explained in this post)