Best way to solder ribbon cable to controller board?

[Nakula]

My most recent project involves turning a laptop keyboard into a usb keyboard fr desktop use. I pretty much know what I have to do at every step, but having to solder the laptop keyboard ribbon cable to a regular keyboards logic/controller board has me kinda stumped. The ribbon cable is the very thin kinda. It is almost like film. It goes into a surface mounted female ribbon header which leads to several tiny pinouts to the PCB. What I have figured thus far is to desolder the female ribbon header and manage to solder small wires from the header pinouts to the keyboard controller where it's keyboard matrix outputs lead to. Then just plug the laptop keyboard ribbon to the moved header. From there I hope to get unique scan codes from each key on my new keyboard and just remap them with keytweak. My issue here lies in soldering wires from the ribbon header to the keyboard controller. Is this the best way to connect the header? Are there better methods to connecting a header to a circuitboard it was not intended for? Thx in advance

[dorkvader]

I work on laptops almost every day.

Most laptop keyboard cables are not solderable (they are like M membranes).

In truth, it depends on the laptop. Some use nice gold plated ribbon at the end of the connector that you can solder to. Most are just the end of the bare membrane.

Your best bet is to buy the "other" end of the connector (the one on the motherboard) and solder to that.

Based on your description, it sounds a little like a modern Dell (or HP) controller, where the KB matrix plugs into a controller, which then plugs into the motherboard. I believe these output USB natively to the MB, and might carry extra power for the backlight (if present).

Basically, I will need more info or a picture to best advise you.

[mkawa]

ribbons should be crimped into connectors or ZIF socketed. soldering ribbons will give you a bad day.

[Nakula]

ill get pics up here as soon as possible. right now my laptop is at a friends house (he had all cool tools for laptop disassembly). so for now i can only use words to describe. i already figured it would be near impossible to solder the actual ribbon cable. so i was trying to basically figure out how to solder the pinouts on the thing it connects to (i believe its called a ribbon cable PSB female header/connector) to the connection points on the keyboard controller where its original keyboard matrix pinned out to. i guess my question is more acutely, how to solder a ribbon cable connector to a circuit board it wasnt designed for. i obviously couldnt surface mount it to the keyboard controller cause im doubting HIGHLY that the connection points for the keyboard matrix are the same shape/number of pins/etc as the ribbon connector. so that led me to thinking i could run wires from each pinout of the ribbon connector to the connection points on the controller board. but ive never soldered something that small. i mean those ribbon connector pinouts are tiny! is there an actual method of doing what im trying to do, or is this a wonky mod through and through, and theres no clean solution? my circuit building/modifying skills are non existent, so i really just have no clue how to do this particular step in the process.

[dorkvader]

What brand / model laptop is it? Maybe I can take a picture when I'm at work.

[Nakula]

Acer 7551

[dorkvader]

Acer 7551

You aren't going to be able to solder to that. You can get a connector, and solder leads to it, then solder those leads to a teensy.

Unfortunately, such connectors are usually surface mount and can be quite fine pitch.

[Nakula]

what is a teensy? and what do you mean by fine pitch? do you think its even possible to solder leads to those super tiny connector pinouts? what gauge wire whould i use?

[Smasher816]

A teensy is a small programmable microcontroller. They are often used here in projects to control the "firmware" of a DIY keyboard project.

A fine pitch just means small gaps between pins/connectors.

[dorkvader]

what is a teensy? and what do you mean by fine pitch? do you think its even possible to solder leads to those super tiny connector pinouts? what gauge wire whould i use?

teensy: http://www.pjrc.com/store/teensy.html
If you bought a matching connector for that cable, it would be possible to solder to it, get very fine gauge wire gauge (24-28 if you can get it) though anything up to the pitch of the connector should be possible (but more difficult).

[Nakula]

anyone have any good videos, tutorials, or just good tips on hows to solder leads onto tiny ribbon cable connector pins? ive never soldered something that small, so i need all the advice i can get before trying this.

[0100010]

Have the Science Channel?

There is a 1pm episode of How It's Made on 6/14/14, that has a segment on flexible circuit board manufacturing.  One of the last scenes shows a socket getting soldered on to the end of a ribbon,  by a worker using a microscope and very fine solder.

[dorkvader]

anyone have any good videos, tutorials, or just good tips on hows to solder leads onto tiny ribbon cable connector pins? ive never soldered something that small, so i need all the advice i can get before trying this.

When I do fine soldering, I get a really fine tip on my iron (edsyn has a lot of really fine tips). then I pre-tin both the cable and the connector. then I merely use the iron to combine the two. Still, it can be hard, especially to get them to stay together when the solder is freezing.