Hi Luis,

IPC-A-610 revision B states in chapter 4.1 : "There are solder alloy compositions, lead or printed board platings and special soldering processes that may produce dull matte, gray, or grainy appearing solders that are normal for the material or process involved. These joints are acceptable".
What you're seeing is a result of gold in the solderjoint, not of the temperature profile. You can test this by pretinning some of these parts.
Whether the amount of gold in the joints (gold embrittlement) is acceptable for your product is another discussion. 

Kind regards

Daan Terstegge
SMT Centre
Signaal Communications
Unclassified mail
Personal website: http://surf.to/smtinfo 

>>> Luis Alcantra <[log in to unmask]> 03/22 5:56 pm >>>
Hi every one:
             We are currently experiencing some dificulties soldering gold
plated pins, they go on a 1/2 of an inch square pcb w/a cap an a resistor.
we had tried several profiles with no satisfactory results, we are using
kester #Sn63Pb37 solder on a Vitronics 722 20 zone reflow oven as follows:
165-175-250-  -260-260-260-260-260-280-400 degrees temp. it may seen to
high but our pcb fixture is thick an pcb bar holders on each side.

The problem is solder looks GRAINNY/COLD any suggestions for a good solder
paste/profile?

regards.

LUIS ALCANTARA
ENGINEERING DEPT.
[log in to unmask] 
(623) 516-3700

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