Thanks Robert,
I read the paper with interest but note that fused lead free solders were
not compared. Lead free solders can be applied using adapted HASL machines
and result in more uniform surface and hole coatings. The lighter alloys
require less energy to level resulting in a much tighter thickness range
with improved 'minimum' thicknesses and significantly lower 'maximum'
thicknesses. Hole clearing is more uniform with less closedown. If you or
anyone else would like us to tin some sample to compare please do not
hesitate to contact me. We have SnCu+Ni permanently available and will be
conducting trials with two SAC alloys in the next few weeks...
Peter.
-----Original Message-----
From: Hilty, Robert D [mailto:[log in to unmask]]
Sent: Thursday, May 27, 2004 4:54 PM
To: [log in to unmask]
Subject: Re: [LF] Lead Free design guides for press fit
Carl:
We published some info on lead free press-fit components on our lead free
website at: http://www.tycoelectronics.com/environment/leadfree/techdata.stm
I am not surprised about an increase in force. For our testing, we found
that compliant pin (eye of the needle and action pin style) had a general
increase in insertion force of about 8% when compared to bright tin/lead
finishes. The biggest cause for this increase is the conversion from a
bright finish (smooth and harder) to a matte finish. The matte finish has
been dictated by many customers due to whisker concerns. Tyco's testing has
also shown that in general there is about a 21% increase in retention force,
which ultimately leads to increased reliability in the joint.
Our testing of compliant pins includes testing at the boundaries of the hole
tolerances for various pins and board finishes. If the holes were in
tolerance, then we saw no evidence of fractured barrels or cracking in the
devices. If the plating is out of tolerance, then some issues can arise.
The most common fault is when the nickel thickness is too large on board
finishes that use nickel; this can lead to cracking of the nickel.
If you have further questions, please contact me directly.
Cheers,
Bob Hilty
Tyco Electronics
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]]On Behalf Of Carlr Ray
Sent: Thursday, May 27, 2004 8:43 AM
To: [log in to unmask]
Subject: [LF] Lead Free design guides for press fit
Hi All,
Does anyone have any information for design rules for lead free compliant
pin operations? We encountered an issue yesterday where during our press fit
operations our equipment keep reaching force insertion limits. After we
spent hours we finally reached the conclusion that the components we were
using were lead free. The vender changed the plating without changing the
part number or notifying us of the change. So we now have mixed inventory
and are in the process of sorting this material. This brought up major
concerns with processing of compliant pin operations. Quality concerns are
with the current design if we can no longer get these components with lead
plating then how will the current design and process react to the lead free
components. Fractured barrels, cracked or damaged devices and PCB stress are
concerns and will impact field reliability. Any information would be
greatly appreciated.
===============================
Carl Ray
Manufacturing Engineering Manager
Plant 520 (Kenosha Operations)
Pleasent Prairie, WI 53158
Desk: TBD
Fax: TBD
Cell: 256-990-1990
[log in to unmask]
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