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Lead Free ...

Hi, In 2006 we will need to produce Lead free PCB and for... - Aug 30, 2004 by Frank R.  

#30290

Lead Free ... | 30 August, 2004

Hi,

In 2006 we will need to produce Lead free PCB and for now it's hard to get answer to my questions. I'm from Canada and the PCB vendors we actually have are not ready to produce Lead Free PCB ( HASL Lead Free ). For sure OSP (Entek) is not good for me. I produce 400 000 PCB per year so the price is very important but the PCB product must be easy to handle.

I participate to a lot of seminar and I receive document from AIM, Kester, Motorola, Loctite and a few PCB vendors in canada. A lot of representative say they know a lot of things concerning lead free but they never work directly with it.

I know that japanese company are completely switch to lead free but they use local solder paste company for lead free product.

Is someone in this site produce about the same quantity of PCB 400 000 / year( or more ) in lead free ?

I have a few questions for you.

Thanks Frank

reply »

KEN

#30297

Lead Free ... | 30 August, 2004

I worked for a US leading edge technology company to develop smt and wave solder processes to be transfered to their Tiawan CM. Its not 400K units per year, but800K per month!

And yes, your right, no one wants to give away the magic lead free process beans...but we may be able to point you in the right direction.

IF price is so important, why disqualify OSP? There is no cheaper LF surface finish.

What is your question?

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#30311

Lead Free ... | 31 August, 2004

Thanks Ken for your reply.

Concerning OSP, there are a few negative points that I must considered for our application.

I've read all the following points in an Entek document. Never test it.

- If you have a miss print and you clean the PCB, the coating thickness on your pads change and the shelf life is affected. They recommand to have a setup PCB that we can use for each screen printing setup process. But we have 200 different PCB. Do we have to manage setup PCBs ... mmm. We produce 15 different product per 8 hour with setup time of 3 to 5 minutes.

- Some products have component on both sides. Shelf life is different on this PCB either.

Here is a part of the article ...

Production experience has shown that hold times of up to 24 hours are typical and SHOULD NOT be of a concern (NOTE: This is not apply to PWBs that have been wiped-down or cleaned with solvent.

For us, after SMT process, PCBs can wait for a few days ( 1 to 7 ) depending of the priority of each JOB. Actually we don't have any problem with shelf life.

IMPORTANT : In this artice, they always compare OSP with Lead Free HASL. It seems to be the reference for perfection.

Manual modification ...

To make a good solder on OSP product, the flux must be in contact with OSP and then the PORES open. Then you can solder your component. BUT if you use a wire solder with flux, is it easy to solder because the flux do not have the time to open the pores before making a good solder.

What is your impression about that ?

This is it for my first group of questions ....

And you Ken, what type of PCB finish are you using? For what reason and is it easy to handle?

If you want I can attache the Entek Document but I don't know how.

Thanks Frank

reply »

KEN

#30323

Lead Free ... | 31 August, 2004

If you have control over your design (as in an OEM) ENTEK can be a managable alternative.

IF your like me (a CM), you get one of everything ever imagined.

There has been much ado with ENTEK. Not every product is apropriate. For instance I have customers that buy ISA / PCI based frame grabber boards for "desktop" vision processing. Sometimes customers see the boards and think the quality has been comprimised because it looks "different". The solder doesn't flow to the corners etc. Is it less reliable. No. Does it look less reliable? To some yes. That's the hardes sell and a battle many do not want to under take.

I can not tell you if ENTEK is a suitable choice for you, and neither can anyone else on the web without a signifficant survey or your factory and your processes (incomming / receiving to shipping). Also, you will find your processes / materials may need to be modified to maximize quality. Entek is rarely a drop-in for most factories without some changes (storage, handling, cleaning, processing etc.).

The most favorable surface finishes are Immersion Tin / Silver, ENIG, HASL, OSP.

I developed my processes for OSP, Tin, Silver. ENIG was given the boot early (800,000 boards per month). However, there has been some recent discoveries with Silver and micro-voiding - a phemenon I ran into in early 2003.

If you only get one ting out of this it should be this: You better get moving on evaluations for design, materials and processes (which may dictate design). And when your not working with LF you should be reading about it!

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#30327

Lead Free ... | 1 September, 2004

Here I want to ask 1. Is Lead Free soldering really meaningful when the total lead content in the PCBA industry is less than 0.02% when compared to the other industries?.

2.The lead free soldering transition has to take place in the following industries. 1.PCB 2.Component 3.PCB Assembly Do you feel all these transition will take place before 2006? Any initiation ahd been taken from the component manufacturer's side? 3.The SOldering finish is completely different from Conventional soldering.Any action had been initiated on formulating the standard for Acceptability? 4.FOr a contract Manufactuting COmpany the customer may not be willing to pay higher price for Lead free soldering and moreover he will be comfortable with conventional soldering as he need not search for lead free components.

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#30332

Lead Free ... | 1 September, 2004

Hi Ken,

It looks like you have some solid practical experience in the transition from leaded to lead-free soldering. I hope you don�t mind me asking a question.

With conventional soldering we have a library of workmanship standards available (SMT, wave and hand soldering) to determine acceptability levels of various kinds of solderjoint imperfections.

Question: how did you implement the acceptability levels for lead-free and what wetting angles did you allow? (core indicator in conventional leaded soldering)

The reason I ask this question is because I�m a strong opponent of lead-free soldering, because at this point in time I have not seen objective scientific research with empirical data showing that the unleaded alloys are reliable, and effects of different lead-free alloys combined and maybe most important the absence of norms. (Salesman�s dream)

I�m afraid the focus has shifted from our old fashioned priorities �quality, reliability and economy� to a no norm at any cost lead-free environment.

Ken, I hope you can shed some light on this by sharing your experience with lead-free.

Thanks, Patrick

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Frank

#30334

Lead Free ... | 1 September, 2004

I don't think you answer all my questions concerning modifications and shelf life after SMT process.

With the experience you have, could you please give me a clear answer please.

Frank

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KEN

#30345

Lead Free ... | 1 September, 2004

The alloy I have chosen uses a wetting angle of 50-70 degrees. Different alloys have different properties. I coupled experimental data with what others have published. Nothing new here.

As for reliability...I think you'll be surprised what lead free alloys have to offer. Why do you think the automotive industry went lead free over a decade ago? Because its cheaper? Nope. Improved reliability. Increased mean time to failure. Period.

Companies like Hitachi, Sony, Panasonic have embraced this transition. In fact I read recently when Hitachi converted over their defect levels at wave solder were over 5X tin/lead. However, they got smart, embraced the problem and now produce wave assemblies with LOWER defect levels than the standard model at tin/lead.

You won't find what you need in a book, seminar or on the web. You're going to have to get hands on. Develop your process...and no, it won't be easy or cheap.

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#30351

Lead Free ... | 2 September, 2004

With all the respect I have for everybody on this site, It's always the same story when it's time to talk about lead free. You try to get specific informations concerning production but ... we only have general answer that everybody from SMT industries can answer.

In the past Dave F. answer all questions I ask for.

But concerning lead free ... It's hard to find a reference person.

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#30352

Lead Free ... | 2 September, 2004

Hi laxman,

Only to answer one of your question, actually almost 50% of component we use switch to lead free alloys. We receive confirmation for transition to lead free of at least 10 components per day. So, Yes I think all component will be ready for summer 2006.

Regards, Frank

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RDR

#30355

Lead Free ... | 2 September, 2004

If you are concerned about shelf life and handling of raw or partially assembled PCBs use Immersion gold and hope that you don't get black pad, I still love this finish but I have been fortunate to never receive bad boards. If I understand your question correctly you don't want OSP but don't want to pay for anything else except HASL. (If you want Corvette performance, don't buy a Yugo).

OSP does have it's problems in regards to incoming shelf life,processing does degrade the finish, each time it is heated, cleaned, etc... The tin and silver finishes suggested also require special handling/storage. You have to make a decision as Ken stated. You will need to modify your processes and mode of operation for OSP, meaning when you start the build you finish the build. Handle the PCBs properly, Do not order PCBS to far in advance and don't over order.

There are PCB suppliers that provide pb free HASL, maybe not in Canada but they are prevalent in US and overseas. Do you process any fine pitch <20 mil? 0402,0201 type parts? HASL may not be the right finish anyway. As far as cost is it not the customer that dictates the pb free requirement? If they need pb free they have to pay for it. As far as paste, everybody (generally speaking) makes it now and you can buy paste from Japan if you so desire.

Here is my take on lead free SMT processing

Get lead free parts Reflow at the specified time/temp for the alloy you have chosen. It appears that the SAC 305 to 405 is at this time the chosen alloy. (Tin/Silver/Copper)

Did this answer your questions?

Russ

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#30356

Lead Free ... | 2 September, 2004

Greetings from the UK: I have been quite fortunate to lead (no pun intended) our company towards lead free sooner rater than later. One of our customers produces a product which is refurbushed every 6 months or so and sent back into the market. According to the DTI this is classed as a new product and hence is covered by the European Legislation. Therefore they want us to produce 'Lead Reduced' product (i.e. through a lead free process) ASAP. Anyway, we are advising all of our customers to switch to Silver from Tin Lead HASL (none currently use OSP):

OSP For: Lowest Cost/Environmentally Friendly/Easy Rework Aga: Shelf Life Concern/Cosmetics/Process Optimization/Thickness Control (measure)/Ease of Contamination (handling)

Immersion Tin For: Low Cost/Easy Rework/Simple to Produce Aga: Environment (thiorea)/Tin Pest/Tin Whiskers/Cu:Sn Intermetallic Growth

Immersion Silver For: Moderate Cost/Moderate Shelf Life (Gold x2)/Good Industry Experience Aga: Availability/Solderability Degridation After 1st Process)/Little Industry Experience

Palladium For: Robust/Used For Boards With On-Board Switches Aga: Too Expensive/ Solderability Issues

ENIG For: Proven Record/Cosmetics/Robust Aga: Can Attack Solder Resist/Fairly Expensive/Concerns Of BGA's Under Flex Testing

There are many more options, but these are the main options. The rule of thumb is to go with the cheapest which works for you. All of our customers boards are HASL and our board suppliers have offered to supply Silver finish boards at the same price. Apparantly they will be glad to see the back of HASL because it is such a nasty, messy process.

I hope this helps! I will try to set aside some time to answer Laxman's questions later.

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#30358

Lead Free ... | 2 September, 2004

Thanks Russ,

Concerning PCB, I will consider positive and negative informations for all material exept OSP. I work with 350 persons in production and if the final result of the product is different depending of the person who andle it, I can't use this material.

We don't have fine pitch 25mil, 0402 and 0805 a lot.

Do you work with lead free now ?

Other question: For component inspection, with everything I've read, I think it will be good to have a lead alloy detection tool to be sure that all component we receive do not have lead. Are you doing something special for lead free component you receive?

Thanks Russ Frank

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#30359

Lead Free ... | 2 September, 2004

Hi Ken,

Thank you for the reply Ken. I hope I don�t get my behind in trouble for subject change in this thread. But you hit the nail on the head in your comment with Hitachi, when they converted to lead-free they had a �5 times higher defect rate� in my opinion that was because they tried to match the known leaded standards. And when they realized that this was impossible they just removed the standards and the results were fantastic. My concern is that with lead-free every individual company will have to generate their own acceptability norms depending on alloy used in paste or wave, board and component plating (the scary part is that we might be dealing with 4 different alloys). When a sound �new technology� is developed and marketed it comes with clear process parameters and min/max acceptability levels matching industry standards, I haven�t seen this with lead-free except for chaos and open ended speculation. (Wetting angle is not a standard only for soldering, but it measures resistance to flow for all liquids)

Ken, just assume you start your own assembly company tomorrow and you had no limits in alloy choice would you solder lead-free?

Thanks Patrick

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RDR

#30364

Lead Free ... | 2 September, 2004

Frank, We are currently running lead free for approximately 1 yr. now but no where near the volumes you have mentioned. We are about 5k units per month. I personally am in agreement with you as far as OSP. I also do not like white tin finish since it seems to have the same problems as OSP in regards to solderability after thermal processing. But I do believe that either OSP and Tin can be great finishes if done correctly at the fab house and in production.

We currently use immersion silver on these products and have had great success unless we take the PCBS out of the siver saver paper too early. I do not know yet how long they can be removed from this protective paper but I know that it needs to be less than a week at least in our environment. We experienced pretty severe tarnishing on these boards that were removed from the paper but they did process somewhat. The solder joints were good but all areas that did not receive reflow/solder looked pretty bad. These assemblies are also single sided so I personally do not know if double reflow has an effect on the solderability.

As far as verification of lead free, We utilize the certs from the mfg. Unfortunately some of these parts are consigned to us so I do not know if the consigner is doing any special testing.

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#30365

Lead Free ... | 2 September, 2004

Thanks Russ, very interesting.

Are you working with a printer, PNP, reflow and wave?

Did you change apertures in your stencils with lead free ?

Concerning reflow, do you have a 5 zones, 7 zones ... ?

Are you using the same alloys for solder paste and wave ? I ask you this question because someone told me that we can use Sn/Ni/Cu without endomaging the solder pot.

Frank

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RDR

#30367

Lead Free ... | 2 September, 2004

We don't do any wave, SMT only. We did not have to change apertures for lead free, we use the same stencil that we did when we ran water soluble with pb. This I think might be dependant upon your current design of both pad and apertures however. Here is the fun part, we started the lead free with a 4 zone and 3 zone table top ovens and ran it for almost a year with no problems whatsoever. I do not reccomend this to anyone however. It took a long time to get the profile right and this product is a simple board meaning that it is only .048" thick, single sided and well balanced thermally. We have recently purchased a 5 zone and it works fanatastic!

I was at a pbfree seminar (read sales pitch) recently and the company ginving was bragging about their alloy being able to be used in current wave solder machines with no adverse effects. The company was Florida Cirtech and the solder bar was called SN100C. I believe that it is Sn,Cu,Ni alloy as you mentioned. http://www.floridacirtech.com

Russ

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KEN

#30373

Lead Free ... | 2 September, 2004

Patrick

You have no idea if company xyz changed its standards, developed new processes or selected new materials yet you cast doubt. To nay-say their intregrity with out a shread of evidence reflects poorly on you.

My company offers lead free services. We will service the needs of this market. Others will choose not to.

Its no different to any other milestone in Electronics Manufacturing....some will embrace the challenge....othes will not.

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#30384

Lead Free ... | 3 September, 2004

That's what I have ... two 5 zone reflow. A representative from AIM told me that 7 zone reflow is required with PbFree. It's good to know that it work fine with a 5 zones.

Florida cirtech is the company who told me that SN100C do not damage your wave solder POT. I think it's an exclusive product for them.

Concerning manual modifications. Is it something easy to do? What do you think about it?

When you swith your production to PbFree, did you run PB process at the same time or you completely switch to Pbfree?

Frank

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#30397

Lead Free ... | 6 September, 2004

Hi All

We have been manufacturing lead free in the UK for about two years now in a fashion. Let me expalin. Two years ago we began to change over our wave solder machines to lead free process. We read all the articles and attended the seminars on lead free and were also concerned about the change.

In the end we decided we just had to go for it and changed over one pot removing all the lead solder and introducing lead free. We increased the pot temperature by 5 degrees and also had to monitor the balance of the bath daily. Once you have this system in place it's easy and we changed over our other baths one at a time in the same way.

We did this and continued to run with lead and lead free parts and this had no affect on the product (Testing already carried out at parent company in Japan). Once we were happy with this we then concentrated on the reflow side. All our suppliers were contacted and told they must supply us with lead free parts by a certain date (For us this was the end of 2003).

We then looked at our machines to see if there were any issues with changing over to lead free paste which to us were the screen printer, oven and AOI. We had no choice on the paste we could use as this was determined in Japan and this was the Senju ZSC-M705GRN360K2V particle size 180-220. We carried out some test prints on the KME SP20 screen printers using rubber squeeges and found no issues here. We left the aperture size of the screen the same as for lead PCB's and did not have to shange any of the settings.

We had some issues with our 5 zone ovens as they had no forced cooling on the output and were unable to reach the higher temperatures (1995 models) so we needed to upgrade. We purchased the BTU Paragon98N with twin forced cooling on the second hand market and found these machines to be superb. I would highly recomend these machines to anyone.

The AOI was not a big issue either other than we had to rewrite the shape files and definitions because the shape, reflection and brightness are affected when changing to lead free.

We have now been building on seven reflow lines lead free product for about six months with no issues we didn't have when building with lead paste. I must admit we were worried with all the negativity in the industry but there really is no need to be concerned.

Oh yes and the final point is we are populating around 1.6 million PCB's a year and the PCB's we use are OSP and we don't have any issues with the boards. However saying that we unpack the PCB's the same day they are to be used and if we need to clean a board it is put down the line straight away. From unpacking to wave solder this is generally completed in 3 days however we do have boards which have reflowed through Aside and gone into repair and not reached wave solder for a couple of weeks due to build schedule.

I hope this helps you.

Cheers

Terry

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#30398

Lead Free ... | 6 September, 2004

What alloy are you using in your wave's?

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KEN

#30417

Lead Free ... | 7 September, 2004

If you want someone to do it for you, hire a consultant.

IF you think its going to be handed to you over the web, get real. I don't think coke Inc would be where it is today if it published the formula to coke. For that matter, any CM or OEM would not consider delivering the lead free "intelectual property" to the WWW as an act of faith and good will towards mankind.

Maybe thats the difference between technology driven companies and others. They have chosen to invest in the knowledge, research and DEVELOPMENT, rather than ride the coat-tales of others.

Reminds me of the clone PC wars of the 80's. Rant done.

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Rick

#36632

Lead Free ... | 13 September, 2005

Lead-free has been around in Canada since 1999 - there are PCB shops that can offer a multi[le of finishes - you just have to look for them

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EddieW

#36638

Lead Free ... | 14 September, 2005

Well said KEN! Frank, you will not find much out there for free advice on lead-free from anyone besides manufactures who supply equipment and material for lead-free and all they will tell you is to use their stuff cause its the best.

The companies that have invested in lead-free development are not going to just hand out thousands of dollars of research just so others can have it easy. Besides, if converting to lead-free was as simple as reading postings on the web, your dilbert boss would do it and claim all the credit. Then ask you why you think you deserve a wage increase......

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vinc

#36827

Lead Free ... | 26 September, 2005

Just be aware of what Japanese had done. They do not stick to one alloy as it is impossible and depends on the constraint you are facing with. As for Hitachi, according to one advertisment put up in SMT magazine seems to me that they are going for a drop-in approach. So I believe they are using a much lower process temperature ( it could be the same operating temperature as those in tin leaded process)and without the need to change anything in their current manufacturing system

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Anna

#36849

Lead Free ... | 26 September, 2005

What type of alloy and at what temperature do you use for wave soldering? Do you need to modify your machine? I am using SCN but I have problem controlling my bath. Are you running on multilayer board or PTH boards? Do you face any fillet lifting issue? Any acceptance criteria for fillet lifting?

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Dolby Laboratories

#36893

Lead Free ... | 29 September, 2005

Try seeing if this has any answers - its just been published

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Dolby Laboratories

#36894

Lead Free ... | 29 September, 2005

Try seeing if this has any answers - its just been published See http://www.smartgroup.org/experience/experience%20report%202005.pdf

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