Designing A Flexible Flat Cable in Altium Designer 14

[denyzz]

Hello nation , I'm currently doing my summer practice and my advisor wanted me to build a flexible flat connector to serve as board to board wiring . He wanted me to use Altium which I had no idea about . I found some Molex FFC connectors and libraries of them which include 3D model also , but I have no idea about how to actually design it in Altium . I just placed 2 connectors in schematic and connected 4 of their pins since my advisor wanted me to use 4 tracks . In of them 1A flows , in 2 of them 3A flows and in one of them 5A flows .

I will try to upload the photos of what I did when I get to home .

Any help about how to design this stuff is appreciated . Thanks .

 

[marce]

Download this, it will give you figures for current capacity in PCB traces. I would be curious as to the connectors.... I guess this is a purely academic exercise when I look at the current requirements as most FFC connectors only go up to 1A per pin.
Also sounds like you've been thrown in at the deep end.
The schematic is simple enough layout a bit more complex, here you need to understand the basics of Altium, search this forum some guides have been put up in the past.
Finally a couple of tomes on flex circuit design:

**broken link removed**
https://flexiblecircuittechnology.com/flex4/

 

[denyzz]

I read these books(not entirely) but it gives no idea about how to apply these ideas in Altium .

The connectors that I am using are :
https://www.molex.com/molex/products/datasheet.jsp?part=active/0541325097_FFC_FPC_CONNECTORS.xml

In the schematic I put the connectors at two ends of the sheet with pins facing each other and I guess it's correct . Now I will just make 4 connections randomly with trace length as minimum as possible . My main concern is how to place them in the FPC ?

 

[FvM]

If I understand right, you want to design a flex PCB to be used with FFC connectors, not the PCB where the connectors are mounted.

If so, you'll start to sketch FFC copper pattern, either as a library component, or directly in your design.

It doesn't make much sense to start the design without any knowledge of PCB layout in general and Altium operation in particular. Your advisor should know this.

 

[marce]

Basilally straight lines...
of course what I do when I am designing FFCs is get the data sheet for the connector and look at the cable guidelines....

https://www.molex.com/pdm_docs/sd/541325097_sd.pdf

Further to my original comment 5A is not going to go through one pin, you need at least 12 (safety margin) as each pin is rated at 0.5A, so 7 for 3A and two at least for 1A... round it up to the nearest available.

 

[denyzz]

So , for example for 5A , should I use 12 pins and combine them in a node then split to another 12 pin of the other connector to transfer that current ?

 

[marce]

Yes each pin is only good for 0.5A, add a couple for safety...

 

[denyzz]

I asked to my advisor and he said yeah you can do this but instead of it , give 5A by using 12 pins and dont combine them in a node , just route 12 traces from 1 to 1 , 3 to 3 , and so on . And I did that . So basically all of my traces carry like 0.47 to 0.5A .

Since the traces are perfecly horizontal and I know their length , I used
https://www.4pcb.com/trace-width-calculator.html this in order to calculate the required trace widthnesses .

If you think sth wrong about these steps , please inform me .

The last thing he wanted from me is to reduce the EMI noise , which I have no idea about . My PCB has a bottom and top layer . In bottom layer there exists the traces . In top there's nothing .

If you can give me some tips&sources about how to eliminate EMI noise , that would be very cool as well ..

Thanks

 

[marce]

Look at the links in this file, there are some very good EMC guides.