Sn/Pb plating on heat spreader

[Dummy]

I have two different types of cubical heat spreaders. There is a Sn/Pb
plating layer on each surface of heat spreader.
Heat spreader A with 7 micron plating layer thickness.
Heat spreader B with 0.5 micron plating layer thickness.
If both heat spreaders have equal heat conductivity characteristic,
will the one with thinner plating layer be having solderability
problem?
If so, how the thickness of Sn/Pb plating layer is related to
solderability?
I worry that the thinner plating layer will pose the solderability
problem and reduce the heat transfer efficiency.

 

[Rich Grise]

Dummy wrote:

I have two different types of cubical heat spreaders. There is a Sn/Pb
plating layer on each surface of heat spreader.
Heat spreader A with 7 micron plating layer thickness.
Heat spreader B with 0.5 micron plating layer thickness.
If both heat spreaders have equal heat conductivity characteristic,
will the one with thinner plating layer be having solderability
problem?
If so, how the thickness of Sn/Pb plating layer is related to
solderability?
I worry that the thinner plating layer will pose the solderability
problem and reduce the heat transfer efficiency.

It shouldn't make a noticeable difference. The surface is plated
with, essentially, solder. When the joint gets to the right temp,
the solder flows just like with any properly-tinned part. Once
the added solder wets the joint, the plating thickness becomes
moot.

Hope This Helps!
Rich

 

[James Meyer]

On Thu, 12 Aug 2004 04:17:19 GMT, Rich Grise <null@example.net> wroth:

I worry that the thinner plating layer will pose the solderability
problem and reduce the heat transfer efficiency.

It shouldn't make a noticeable difference. The surface is plated
with, essentially, solder. When the joint gets to the right temp,
the solder flows just like with any properly-tinned part. Once
the added solder wets the joint, the plating thickness becomes
moot.

Hope This Helps!
Rich

Soldering results from metals dissolving or alloying at the interface.
If the base material of the spreader is something like aluminum which won't
dissolve in tin/lead solder, then there could very well be a problem with a thin
plating thickness. The original poster didn't state what the spreader material
is and whether there are any other layers of intermediate materials involved.

Jim

 

[Dummy]

James Meyer <jmeyer@nowhere.net> wrote in message news:<8hlmh01c24kt5nmkagb6kb31bvq07l7ooe@4ax.com>...

On Thu, 12 Aug 2004 04:17:19 GMT, Rich Grise <null@example.net> wroth:

I worry that the thinner plating layer will pose the solderability
problem and reduce the heat transfer efficiency.

It shouldn't make a noticeable difference. The surface is plated
with, essentially, solder. When the joint gets to the right temp,
the solder flows just like with any properly-tinned part. Once
the added solder wets the joint, the plating thickness becomes
moot.

Hope This Helps!
Rich

Soldering results from metals dissolving or alloying at the interface.
If the base material of the spreader is something like aluminum which won't
dissolve in tin/lead solder, then there could very well be a problem with a thin
plating thickness. The original poster didn't state what the spreader material
is and whether there are any other layers of intermediate materials involved.

Jim

For heat spreader A,
1st layer will be Sn/Pb Plating, with 6-8u thickness.
2nd layer is Ni layer with 9-10u thickness
3rd layer Cu layer with 10u thickness
4th and the last layer will be the substrate, which contains Zn and
little Al.

For heat spreader B,
1st layer will be Sn/Pb Plating, with 0.5u thickness.
2nd layer is Ni layer with 2-2.5u thickness
3rd layer Cu layer with 20u thickness
4th and the last layer will be the substrate, which contains Zn and
little Al.

Surface element of the Heat spreader A is Sn/Pb mainly; while for Heat
spreader B, the main elements are Ni and Cu, with little content of
Sn.

 

[James Meyer]

On 12 Aug 2004 18:26:37 -0700, ahkit1021@yahoo.com (Dummy) wroth:

James Meyer <jmeyer@nowhere.net> wrote in message news:<8hlmh01c24kt5nmkagb6kb31bvq07l7ooe@4ax.com>...
On Thu, 12 Aug 2004 04:17:19 GMT, Rich Grise <null@example.net> wroth:

I worry that the thinner plating layer will pose the solderability
problem and reduce the heat transfer efficiency.

It shouldn't make a noticeable difference. The surface is plated
with, essentially, solder. When the joint gets to the right temp,
the solder flows just like with any properly-tinned part. Once
the added solder wets the joint, the plating thickness becomes
moot.

Hope This Helps!
Rich

Soldering results from metals dissolving or alloying at the interface.
If the base material of the spreader is something like aluminum which won't
dissolve in tin/lead solder, then there could very well be a problem with a thin
plating thickness. The original poster didn't state what the spreader material
is and whether there are any other layers of intermediate materials involved.

Jim

For heat spreader A,
1st layer will be Sn/Pb Plating, with 6-8u thickness.
2nd layer is Ni layer with 9-10u thickness
3rd layer Cu layer with 10u thickness
4th and the last layer will be the substrate, which contains Zn and
little Al.

For heat spreader B,
1st layer will be Sn/Pb Plating, with 0.5u thickness.
2nd layer is Ni layer with 2-2.5u thickness
3rd layer Cu layer with 20u thickness
4th and the last layer will be the substrate, which contains Zn and
little Al.

Surface element of the Heat spreader A is Sn/Pb mainly; while for Heat
spreader B, the main elements are Ni and Cu, with little content of
Sn.

Nickel, copper, and zinc are all compatible with ordinary tin/lead
solder. You can solder to any of them. The plating layers are rather thin
though. A solder preform or paste along with just enough heat, using hot air or
an oven, to get the job done would probably work with either spreader.

Since there are so many variables involved, your answer will probably
have to be gotten using empirical methods. Try several samples with different
methods and test the "peel strength" of the resulting joints.

Jim