Mixing Hole through and SMD - Page 1
Forum section: electronics / general

author: K6TR
author_rank: Regular Contributor
timestamp: July 20, 2015, 08:11:12 pm
content: I'm designing a PCB that will use an SCR in a crowbar circuit. The problem I face is the SCR is available in two packages the more available is a Hole-through in a TO-220 package. The device with the higher voltage rating is an SMD Device in a TO-263 (SOT 23) package. I designed the board for either device with the Hole-Through designated as Q3A and the SMD as Q3B. Both are wired in parrallel so that only one needs to be populated. When I go to create PCB will the program lay out the foil side opposite the components for the TO-220 and put the foil for the TO-263 on the component side inserting the necessary vias ? I ask this because I may want to increase the size of the vias in order to handle the necessary surge current. Thanks in advance.Bob

author: zapta
author_rank: Super Contributor
timestamp: July 20, 2015, 08:38:10 pm
content: Quote from: K6TR on July 20, 2015, 08:11:12 pmWith eagle and I presume with any other cad software you can choose the PCB side of each component.

author: McBryce
author_rank: Super Contributor
timestamp: July 20, 2015, 08:58:50 pm
content: In the DIPTrace PCB Layout editor: Select the component, right click on it and choose "Change Side" in the popup menu and it will flip sides.McBryce.

author: DerekG
author_rank: Frequent Contributor
timestamp: September 20, 2015, 12:42:38 am
content: Quote from: K6TR on July 20, 2015, 08:11:12 pmVias are often added so that the copper that is plated through them increases the current carrying capacity. The vias also aid heat transfer to the other side of the board (which often contains an exposed copper fill acting as a heat sink).I have some mosfet designs that have (in their pads) around 80 vias of 0.3mm with a 1mm spacing for heat dissipation.

author: K6TR
author_rank: Regular Contributor
timestamp: September 21, 2015, 06:09:49 pm
content: Quote from: DerekG on September 20, 2015, 12:42:38 amThanks Derek and McBryce for the info. I was able to address the problem I had to my complete satisfaction. Although I purcahased my first license a little over a year ago I did not work on designing boards for a few months. I have designed 4 ranging in complexity from simple to fairly complex. Although I still have a great deal to master I am now past the the Steep Portion of the Learning Curve. Between the Tutorial, the Guided Tours and other videos on the Internet I am able to get my questions answered very quickly. And the questions are coming at longer and longer intervals. I figure I will have this Software Package under my belt to the point that I can design anything in another 6 to 9 months.Another point that the folks at Dip Trace may find interesting. John Hopkins University School of Biomedical Engineering has set up their own Youtube Webpage. "BME Builds"https://www.youtube.com/channel/UCK9uRj5u4afQGQWWFtU0jPAIt is mostly. about electronics and features 7 Videos on Dip Trace. Looks like at least one US University Program has latched on to Dip Trace.

author: DerekG
author_rank: Frequent Contributor
timestamp: September 22, 2015, 11:51:36 am
content: Quote from: K6TR on September 21, 2015, 06:09:49 pmYou're welcome.QuoteIt takes time to get together all the knowledge required to operate any software that provides solutions to quite complex tasks. The two easiest pcb programs to learn would be DipTrace & Circad. The DipTrace developers are more active & the price point is better.I also use Proteus & Altium for work. I like Proteus a lot & Altium the least.Why not call up one of the board shops near to you & ask for a look through. Once you understand the actual processes in making the circuit board from the beginning to the end, you will have a much better understanding as to why pcb design programs offer you so many options.Many designers still don't know that the first process in making a circuit board is to drill all the plate through holes.QuoteThanks for the video link.