Double row ribbon cables? - Page 1
Forum section: electronics / general

author: lawrence11
author_rank: Frequent Contributor
timestamp: April 30, 2018, 04:22:56 pm
content: Is there any "double row" ribbon cables out there, as per this pcb design.Something that is an immitation of a ground plane but the signals are side by side not seperated by ground wire, to save space in an axis.I know it will be hard to splice but I will just use a razor blade and seperate the row.

author: mariush
author_rank: Super Contributor
timestamp: April 30, 2018, 04:39:44 pm
content: You can buy ribbon cables with the ends pre-cut and tinned so you can just bend the wires a bit and solder them in the holes.. for example :https://www.digikey.com/short/j4h0trThere's also ribbon cables of various number of wires and lengths :https://www.digikey.com/short/j4h0qjand there's connectors which you can use with these ribbon cables to separate them in two rows ... see these :https://www.digikey.com/short/j4h0jw(you just slide ribbon cable in them and press the top down and the pins "bite" into the ribbon cable)... then you can solder the pins of the connector to board if you want.

author: wraper
author_rank: Unknown
timestamp: April 30, 2018, 04:47:32 pm
content: Normally you should use connector which makes it double row by design. Soldering ribbon cable directly into PCB is prone to break, and if you do it double row, it becomes even less reliable.

author: nctnico
author_rank: Super Contributor
timestamp: April 30, 2018, 10:04:35 pm
content: Quote from: wraper on April 30, 2018, 04:47:32 pmI agree. In general soldering wires to a board is asking for problems. Better use a connector with a strain relief.

author: lawrence11
author_rank: Frequent Contributor
timestamp: May 01, 2018, 05:02:44 am
content: This is a fixed connector on the same board, it stays at same temperature.

author: janekm
author_rank: Unknown
timestamp: May 01, 2018, 05:09:23 am
content: This layout doesn't make much sense at first glance, can you expand on what it's trying to achieve?It seems based on the routing on the PCB that these are not differential signals but they are placed together encouraging coupling between them, despite there being literally a dozen ground wires available to separate them.To answer your question, i haven't seen actual double row ribbon cables but only half pitch which is split into the two rows as mentioned by others.You can get shielded ribbon cables though which may achieve the intent of this design if it is to shield the signals?

author: lawrence11
author_rank: Frequent Contributor
timestamp: May 01, 2018, 05:25:16 am
content: I cant use a connector, there is no space and I dont feel like remaking everything to make it bigger and have to buy connectors on top of that. Every signal wire is SIDE BY SIDE, and underneath that is ground plane or a grounded jacket, thus double row. You can use this tactic since the fields will be controlled and no crosstalk will happen due to ratio of seperation vs distance from plane. Bu doing this I save space in the critical axis. I am deciding on wich 1.27 ribbon I will buy.I was gonna use either ground plane ribbon cable or jacketed ribbon cable, for a very dense fit. The second layer of holes is to provide low impedance termination to the ground mesh or jacket depending on the ribbon cable I choose. I will provide solder points seperated by mask lenght all across those holes and connect the ground plane there, and essentialy provide another layer on the Z plane for an area that is challenging to resolve without resorting to more layers.Then in between the holes where there is mask, I will add a bit of relief with a blade so that mesh dont go too close to pcb.But what I realled wanted, was simple double row wire, or "compressable single layer wire", so I dont have to mess with a ground mesh or jacket. The problem now is how to actually take out the insulation of a double row, the mechanics are now all screwed up for a simple 1.27 stripper, so the grounded plane wire might be better.

author: Gribo
author_rank: Frequent Contributor
timestamp: May 04, 2018, 05:51:43 pm
content: There are ribbon cables for double row 1.27mm pitch connectors. Worse case, you can use an FFC/FPC (SMT, low profile, can go to 0.5mm pitch without too much hassle).