{"id":473,"date":"2017-07-21T04:32:18","date_gmt":"2017-07-21T04:32:18","guid":{"rendered":"http:\/\/technotronix.nobat.webfactional.com\/pcbblog\/?p=473"},"modified":"2025-12-11T06:26:56","modified_gmt":"2025-12-11T06:26:56","slug":"how-uv-lasers-helps-in-hdi-pcb-design-and-guidelines-to-design-hdi-pcbs","status":"publish","type":"post","link":"https:\/\/www.technotronix.us\/pcbblog\/how-uv-lasers-helps-in-hdi-pcb-design-and-guidelines-to-design-hdi-pcbs\/","title":{"rendered":"How UV Lasers helps in HDI pcb layout and Guidelines to design HDI PCBs"},"content":{"rendered":"

With advances in UV lasers, the one industry that is definitely benefitting is that of pcb layout. UV Lasers allow for PCBs with shrinking vias, which in turn leads to a number of advantages but not limited to manufacturing dense PCBs at lower costs.<\/p>\n

While with CO2 lasers, the micro vias had diameters of 60-80 \u00b5m, with UV lasers the same figure can be brought down to 15 \u00b5m. Additionally these can be drilled at high speed. In turn this leads to quick production. Also, with less power required to drill this vias, there is less generation of heat. This is especially advantageous where boards are mounted on paper. UV Lasers transfer minimum heat to the board and ensure that the board isn\u2019t impacted.<\/p>\n

The other advantage of small vias drilled with lasers is that vias with narrow diameters leads to production of smaller boards. What it means is that Making boards for Internet of Things, for example, where space is a constraint, becomes far easier. Small vias also enable use of other technologies such as New Ball Grid Array or Via-On- Pads which do not work well with traditional vias. Also smaller boards will typically mean lower cost of fabrication.<\/p>\n

Another distinct advantage of small vias is that they radiate less EMI. Reduction in the size of the via means reduced impedance which in turn means less voltage drop.<\/p>\n

The fact that these UV lasers also offer a distinct cost advantage also works strongly in their favour. Also being able to use these lasers for all cuts and holes allows the manufacturer to save money when it comes to fabrication. In fact the accuracy of UV lasers for cuts and channels also makes a strong case for their use.<\/p>\n

While UVs clearly offer a number of advantages in HDI PCB<\/a> layout, it is however important to keep in mind that Making of HDI PCBs needs to follow some basic tenets which can then add to the PCBs performance. Compared to ordinary PCBs, the HDI PCBs obtain their interconnections through blind and buried holes. Additionally, small spacing is used in PCB Layout to fully utilize the space. To be able to do so, though, it is imperative that the process parameters in the HDI PCB manufacturing process are understood.<\/p>\n

Here is a quick overview of the Manufacturing Process and some aspects to be mindful for HDI PCB Design:<\/h2>\n

Aperture<\/h2>\n

One of the things to consider in hole design is the aperture ratio. In case of mechanical drilling through hole aperture should be more than 0.15mm and board thickness-to-aperture ratio more than 8:1. For laser drilling, however, the aperture of laser hole should be in the range of 3 to 6mil and the plating filling hole depth-to-aperture ratio at 1:1. Also the process of plating makes it difficult for the chemical solution to reach the drilling holes. With the increase in voltage, defects can spring it. It is important for PCB designers to know of these aspects to ensure there are minima issues faced during fabrication.<\/p>\n

Stack<\/h2>\n

There are different categories of HDI PCB layer stack-up basis the order of layers with blind holes. Typical categories include:<\/p>\n