Reliable vertical stacking connectors for Arduino shields with 0.5 MHz signal integrity

Hi All Crusty has a spot of bother which will also form the part of a blog later on.
I have recently made a couple of stacking shields using the type of vertical stacking connectors found on Arduino cards. The problem is after a number of insertions and removals the contacts are becoming less than positive and the 0.5 Meg Hz signals I am pushing through them are getting very hit and miss. Any ideas on vertical pluggable stacking connections for PCB's that have a component clearance height of an Arduino type socket.

Crusty,
Are these connectors gold or tin plated?
For low level signals, you may have better luck with gold plating but that means you need gold on the pins as well.
You also want multiple points of contact within the socket.
Something like this might work...
http://suddendocs.samtec.com/catalog_english/ssq_th.pdf

Elizabeth many thanks It appears that the cheap E-Bay Arduino type sockets start to loose their grip on the long tails when they connect, held in with top force they are ok but degrade on pressure relate from above. They are tin plated.
I am looking at similar options as you have suggested.RegardsCrusty

Crusty
Gold plating is definitely the way to go, but here are some other thoughts.I am assuming that the connectors degrade as you unplug and re-plug during development. If it is because you are removing/working on the micro board you could mount the plug ins from the bottom and you wouldn’t have to remove them that much. Another variation on the theme could be to use flat cable so that you can access either board without actually disconnecting. Surely 0.5MHz shouldn’t have any issue with a few cm of cable? Cables are relatively pricey, but may be worth it if you don’t have to rework the boards all the time.If you use the cable you could add an intermediate connector so the the PCB connectors don’t wear. You could actually work out a scheme that didn’t use the cable I think.By the way- really neat work on the veroboard. I am jealous of your talent.

Hi Aubrey,I normally use idc connectors and a ribbon cable for these types of interconnection and they have no problem. It was just the elegance of the stacking connector that had me go this route. However the ribbon cable does allow for different spacing between boards which can be a bonus.Thanks for the input. I hope my next article will show how I get these boards to look neat. However they are not as neat as the guy who taught me used to get (40 years ago).

Do you remember in the old days we used to stack 40 pin IC sockets and use them as a “buffer” between the micro emulator and the target socket in order to protect the emulator pins?
You may want to try the same technique by building a stack of at lest 3 blank boards that just pass the signals through a la a socket.  When the start failing it is probably easier to make/repair the boards than to repair the operational boards

Thanks every one for the great feedback.I am going with IDC pins and 40 pin ribbon cable.I found some beautiful turned pin sockets with 13mm depth pins that would stack the way I wanted, but they turn out to be £8.00 with vat at Farnell for a 20 pin strip it would make the project about £100.00 just for the plug stacking capability. The 50 off IDC right angle strips and 10 ready made 40 pin cables have only cost £15 on e-bay.Not having a company with deep pockets and tax sink means cheapest method possible.