I'm just trying to figure out how this works.

I just installed a new SSD in my Macbook Air, it's one of these. Have a look at what the pins look like:

enter image description here

When I put it into the slot, for the life of me, as hard as I pushed, I could not get the pins to go all the way in. They're about 75% of the way in.

Now, the way I understand how this works, this doesn't matter, does it? In theory, if only a small part of each pin was touching the connector, it would work, right?

Also, when pushing it hard to get the pins to go in all the way, the SSD board kept bending and flexing. I hoped this was OK.

My two main questions are:

  1. Is it okay if the pins for an SSD drive only go in 75% of the way? (bonus: explain why...I'm just curious...is that really how it works...it doesn't matter how long the pins are, only that some of the metal is touching the metal? Just enough to make a circuit?)

  2. Is it okay if the SSD drive flexed a bit when I was trying to push it hard into the socket? (bonus: explain why...what is in there that allows it to flex, I wouldn't think it would be ok?)

  1. Sure. The further in it is, the lower the resistance across the connection will be, and if the resistance is too high then there may be a problem with the circuitry on the other side picking up the signal. But 75% should be enough.

  2. Yes, provided no solder joints separated and no components were damaged. Thinner PCBs may bend under strain, and some are even designed to be flexible.

flexible PCB

  • re: #1 -- if the computer boots up fine and is working, and i copied about 100gb to the drive...can we be sure that the resistance is not too high? is it a binary thing? (it works or it doesnt?) or is it the kind of thing where the less resistance, the less error ,etc? – MikeC8 Nov 2 '11 at 2:36
  • It's an analog property of the signal, rather than digital. There is a threshold between working and non-working where it may have intermittent errors, but if it's working in your case then I wouldn't worry too much. – Ignacio Vazquez-Abrams Nov 2 '11 at 4:16
  • Cool. Now I'm just trying to learn how this works, but let's say that we're in that realm where it has "intermittent errors". The controller is supposed to take care of that, and I would never actually witness any corrupt data, in theory, right? – MikeC8 Nov 7 '11 at 19:19

The detail in your photo is not that good, but it looks like a printed circuit board (PCB) with an edge connector. The copper contacts of an edge connector are typically called fingers, not "pins", and are often gold plated. The mating (female) connector will typically leave part of the fingers on the PCB exposed, so this is probably what you are describing as "not fully inserted". As long as the PCB bottoms out in the mating connector, then you have no reason to be concerned with the connection.

If the PCB was "bending and flexing", then you were mishandling the board. The PCB should be held on the edges close to the edge connector, and inserted straight into the mating connector. Do not push the board from the far end. Excessive flexing of the PCB can break the copper traces and/or break solder joints.

  • Ok, interesting. Can you go into more detail about what is considered "excessive" flexing? I just want to make sure I didn't damage my drive. I did not know that I was not supposed to push from the end, but also, on further reflection, I'm not sure how else I would have done it, given the angle of the insertion. – MikeC8 Nov 2 '11 at 2:48
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    @MikeC8 - "excessive" flexing is subjective. If the board no longer works, then the flexing was definitely "excessive"; otherwise you got away with it. Instead of brute force, use a side-to-side or wiggling motion during insertion. Next time you have doubts, you should measure (with just a piece of paper) how far the PCB can go into the connector, and then compare how much of the edge connector did go into the female connector. Once it bottoms out, there's never a need to go further! – sawdust Nov 2 '11 at 3:11
  • Thanks for the good tip about the paper. As far as now, with my SSD drive, if it's working does that mean it's not too excessive? :) – MikeC8 Nov 2 '11 at 3:57
  • "...bending and flexing." And break the socket loose from the board it's soldered to. – Fiasco Labs Nov 2 '11 at 4:52
  • @MikeC8: I believe such boards are normally designed so that is not necessary to cause them to visibly flex when inserting them. Insertion forces can be quite high though (e.g. "Board insertion force - 16 oz. max per contact pair" or "Mating Force: 145N max") – RedGrittyBrick Nov 2 '11 at 9:41

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