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Lead Free boards

Views: 1681

#43617

Lead Free boards | 28 August, 2006

WE have been running a leaded product for a few years and while the product is exempt from PB free regulations the components have been comming in lead free reciently and this caused little or no change in the process and or product, However! the Boards came in lead free in this last order. Keep in mind we are running a basic econo-pak with no-clean foam flux and where haveing good success with the process. immediatly upon soldering the first leadfree boards with 63/37 the solder joint quality suffered poor wetting / wicking and in this case "through-hole" an unaceptable amount of voids / blow holes. "more so on high mass parts" ie: terminals, fuse clips" has anybody out there preformed a leaded process through-hole on a leadfree circuit card populated with lead free parts? and if so are these symptoms predictable and curable.

note: we are a CM so controll of product can be difficult. in short we would not have ordered lead free boards.

your thoughts and insights would be appreciated

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Steve

#43619

Lead Free boards | 28 August, 2006

What kind of lead free board? ImSn, ImAg, ENIG, OSP?

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#43620

Lead Free boards | 28 August, 2006

Steve, Thats a good question, I'll go find out.

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#43621

Lead Free boards | 28 August, 2006

Steve,

while I'm trying to find out what type we are working with would it be possible for you to elaborate on the difference? what do the acronyms mean ?

Thanks Bruce

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RDR

#43622

Lead Free boards | 28 August, 2006

Sounds like your PCBs are now white tin. Change this to another roHS compliant finish and see if prob goes away.

You must get control of the materials that you are being asked to build. Your Customer needs your advice on surface finishes, they should not be talking with the PCB suppliers or sales people for finish recommendations

Russ

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Steve

#43624

Lead Free boards | 28 August, 2006

Bruce, I agree with Russ. Seems like you might be dealing with white tin boards. Most likely the least expensive of the choices. Here's a link that I found quickly that will help you with the acronyms I used. http://circuitsassembly.com/cms/content/view/2278/95/

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Board House

#43628

Lead Free boards | 28 August, 2006

ImSn - Immersion Tin - Not Recomended- short shelf life

ImAg - Immersion Silver - Prefered Surface finsh by most Board houses, Best reworkablility, 12 moth self life,

ENIG - Electroless Nickel Immersion Gold - Second Choice for Board Shops, 12 -18 Month self life, No Colored solder masks ohter than Green can go through this chemistry, Blue and Red will contaminate the nickel and gold baths. If Blue or Red is required the board would be 100% plated and then soldermask applied.

OSP - High Temp OSP ( Organic Solder preservitive)- Very User friendly for Board house, not so good for CM's or OEM's unless they are set up for this finish. Finish is applied before shipping product. Chemical spray coating over virgin Copper.

I dissagree that you should not work with your board house. This is a team effort and all sides have pro and cons to finishes and materials, the goal is to make product Manufacturable for both the board house and assembly house to be able to deliver quality product to the OEM.

Regarding the Surface finsh selection, you should pick a finish that the board house of your choice has in place in their facility not outsourced. This will guarantee better controls on chemisty and finish.

Regards,

Mike Board House

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Loco

#43635

Lead Free boards | 29 August, 2006

Just another thought, your leaded boards might have been HASL, which for soldering always flows just a little bit better then other finishes.

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#43644

Lead Free boards | 29 August, 2006

Dear Bruce,

We had the same problem in the same condition. Every compnent and the PCB (OSP) has changed as lead-free and we need to solder them with SnPb. For solution we have increased the flux amount applied on PCB and the pre heat zone temperatures. But the important point is the fluxer i think. Foam fluxer is not a good application. Spray fluxer will be better for you. Depends on the PCB and design maybe you can apply additional air knife.

Best Regards.

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cuculi54986@yahoo.com

#43649

Lead Free boards | 29 August, 2006

Hey Board House,

You forgot to mention Pb-free HASL, how come? I ask because where I work we're running Pb-free HASL as our "preferred" board finish.

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aj

#43650

Lead Free boards | 29 August, 2006

Hi Bruce,

We are a CM aswell and I can sympathise with your situation but you will have to advise the customer that you have issues with this board finish and recommend an alternative. If they are exempt why are they supplying you with Leadfree Boards ??? who gave the go ahead to change if they dont have to? there the questions I would be asking the customer!

Also, do you not have any products that you have to run Leadfree ? we run mixed aswell due to some customers being exempt and also have one wave but we changed the wave to Leadfree to allow us to run the leadfree product.

We monitor the pot closely for contamination but I feel it is much easier to run a Leaded board thru a Leadfree wave Process than a Leadfree Board thru a Leaded Process.

Even though your customer is exempt you will find that most of the parts on the BOM will be leadfree anyway.

aj...

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Board House

#43782

Lead Free boards | 6 September, 2006

PB-free Hasl was not mentioned due to the following:

1)Equipment Convertion at the PCB Manufacturing side is expensive.

2)You are subjecting the PCB to Higher Temps than Std. solder.

3)Most PCB Houses are not going to invest in Two Hot Air level machines. Leaded and No Lead. due to most of us still have Customers that require Lead solder. Avionics / Military / Medical product. plus alternative finishes are cheaper. Immersion silver, High TemP Osp.

The one Plus to the lead free solder is that it does give you a flatter surface finish than std solder.

Sorry for the delayed response.

Regards,

Board House

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