Okay, the concept of a "press fit" has the same basic mechanical issues as a pin and socket connector. I do not recommend any form of sockets on a class 3 board. There are other mechanical issues beyond a metal to metal pin and socket. The plating on the barrel is thin and can result in dissimilar metals in contact. The barrel wall is supported by resins which are considerably more pliable then metal sockets. The CTEs and vibration will cause weakening of the "press" over time. If the "press fit" is for a connector then you have stacked 2 connectors on top of each other. After several years in harsh environments
the intermittent problems are solved by solder the "press fit" pins in the field. The failure info my or may not be reported and or tracked.

I also no longer respond to "ease of repair" arguments for Class 3 hardware. It is counter productive to reliability!

I have participated in many repairs and debates with vendors after field failures are found. The bottom line is once you get past the warranty period the vendor does not show any great concern about reliability and long term failure modes. The use of Performance Based Specifications and extended warranties for high reliability equipment is creating serious conflicts (many of which end up in a small room with lawyers!). What are your contractual obligations, the end use requirements, and how good is your legal department!

This should "light some fires"!

David A. Douthit
Manager
LoCan LLC

Steve Gregory wrote:

Hi David!

Can I ask why? Just thinking about things out loud, you're pressing a pin into a plated through hole that will be deforming the barrel to some extent. Solid press-fit pins more-so than a compliant pin.

Thinking about that, when the connector goes across the wave, it would seem to me that the thermal excursion on the barrel would stress things further on an already stressed barrel...

What advantages are realized by soldering a press-fit connector? As Boston Brad said; Solder the drop in connectors, but leave the press-fits alone...(maybe not his exact words, but essentially the same thing...)

Also, as Charles had said (he has a mind like a steel trap), I did go through this once before with some press-fit connectors from Harting, the finish plating on the pins was nickel, and were never meant to be soldered after talking with an engineer at Harting. The operators were wondering why they had so many solder problems with the connectors before I got there.

By the way, this isn't class 3, it's class 2. But I'm still curious why you would recommend soldering them, when everything I've read, heard, and tried to find out, says that pressing them in is sufficient, and if you solder them, you're asking for trouble.

Respectfully,

-Steve Gregory-
d if you
 

Steve, For Class 3   I would press and solder. David A. Douthit
Manager
LoCan LLC
 

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