FCI

Q1: On a MEG/GIG Array® technology, what would be areas of concern for application in a Mil/Aero environment? Would it be BGA attach ruggedness?

 

Grace Showers: Typically Mil/Aero required higher mechanical vibration and shock requirements. This would be associated with the BGA attach. We typically have testing defined for Vib/Shock as a part of the product requirements contained in the product specification (MEG-Array® Array product spec GS-12-100 and GIG-Array® product spec GS-12-192).

 

Q2: Will the whisker growth make any shorting problem when the finer pitch MEG-Array®/GIG-Array® are made pure Sn plated terminals?

 

Grace Showers: The contact tin areas of the connector are fully contained in plastic so no whiskers will short.

 

 

Molex

Q1: Is the AMC second sourced by Teradyne?

 

David Brearley: The AMC connector is now written in the spec as a "Black Box" footprint. The shape of the connector and the mating interface to the AMC card is specified, but the PCB interface is not. We expect lots of competition in this connector space, with SMT, compression and press fit connectors. Teradyne has not licensed the Molex design to this point.  

 

General Questions/Comments:

Q1: As an end user, the major concern is solder joint fractures at the connector leads (SMT application) that typically happen at the end of the connector due to high mating cycles and how connector suppliers address those concerns.

 

Grace Showers: We have mating cycle tests that verify the connectors performance on this. This is defined as a part of the product specification for both the MEG-Array® (product spec GS-12-100) and GIG-Array® (product spec GS-12-192) products. Product specifications can be found for all connectors on the FCI Web site. Typical failures in the SMT are due to thermal cycling. This is how the long-term reliability is evaluated. This testing is also included in the product specification.

 

David Brearley: Excellent question! SMT solder joints are subject to failure from several mechanisms that must be avoided:

  • Very long connectors are subject to thermal stress during and after soldering. We limit the length. On longer versions, press fit is preferred.
  • Board bow can cause peel of solder joints. We tend to use larger solder "nails" on the ends of connectors, limiting stress on individual solder joints.
  • The 2 row connectors tend to use L leads, which are less vulnerable to most failure mechanisms.
  • This is much more a concern with array connectors that can have hundreds of contacts using rigid solder joints.

John Larkin: Application specifications for all Tyco products are available that address how the connectors are to be mated and unmated. Some connectors that have a high unmating force are fitted with additional holddowns outside the pin field, while other connectors that are rated for a high number of cycles (above 200) will also be designed with additional holding features. Our MICTOR product solves this problem by providing a pivot point outside substantially outside of the pin field. In all cases of high mating cycles, we recommend a rigid PCB or a rigid backer plate in cases of flex film.

 

Q2: The Panel should address issues involving multiple connector applications, such as placement tolerances, lead compliance, etc.

 

Grace Showers: We have many successful multi-connector applications with years of field service as well as some testing to support this.

 

David Brearley: Multiple connectors mating at once are definitely a concern. Self centering on solder pads can help depending on pitch and length. A lot of work was done to prove that up to 4 connectors can fit the IEEE application with 1 mm stackers. It works with 4 connectors in the 64-68 circuits range. Connectors with L shaped solder joints have a tendency to lean to meet mating connectors in an East-West offset. North-South mis-mating is a bit less forgiving. With larger connectors and larger distances between them, more analysis needs to be done to assure mating reliability. Guide pins on larger connectors can help.

 

John Larkin: Most two-piece connector systems are designed with only one set of mating connectors per board considered. The basic problem exists due to misalignment of the connectors to each other, therefore creating plastic-to-plastic interference. This interference creates stress at the solder joints and eventually causes opens to occur. Tyco Electronics typcially addresses this case in our application specifications and provides the necessary connector-to-connector relationship that must be held to ensure minimal stress. Some connectors, like our 1mm FH product, are designed to mate up to four connectors simultaneously. Other connectors within our FH family are offered with an integrated "Bridge", which maintains the connector-to-connector relationship through reflow. We have many years of successful implementations of multiple connectors mating simultaneously and weould be happy to discuss individual application needs with any interested parties.