Indium Corporation Blogs

Here is a picture of an Indium Corporation solder flux pen, sectioned to show you the internals.  Who DOESN'T want to see THAT, right?!?

Flux pens are commonly used to accurately supply small amounts of flux to parts before soldering. In the case of hand soldering solar cells, this is the perfect packaging. As you press the flux pen tip (the yellow part in the picture) against your solar cell, the spring-loaded tip assembly moves back into the body of the flux pen, opening the valve and releasing a small amount of flux into the upper chamber. The pen tip, made of a felt material, carries the flux to the outer surface via capillary action. As you move the flux pen tip across the cell metallization, a thin, even trail of flux is deposited on the surface.

Although flux pens are designed for all types of hand soldering/rework applications, the felt tips generally measure 1.5mm x 4.25mm. This size is great for various sizes of tabbing ribbon!

If you’d like to try using flux pens filled with the best tabbing fluxes available, contact us at solar@indium.com

One of the things that bring customers over to our semiconductor tradeshow booths, year after year, is the pictorial roadmap. This is the diagram you will see prominently displayed, at each show, that demonstrates the process flows for different devices, and how and where Indium Corporation semiconductor assembly materials are used in the process. It's also one of the most photographed things at any semiconductor show as customers, competitors, and others like to use it as a point of reference when discussing their own processes.

The current diagram is about 5 years old, and, in the fast-changing world of semiconductor assembly and packaging, is starting to show its age (although I was surprised to see how many people at Semicon China were still photographing it.)

We are proud to work with Utica,NY-based Paige Group and I spent several hours last week at their offices working with graphic artist, Susan Evans, on the next version of the pictorial roadmap. The interim process is shown at the right: from the scribbled start on the left, to the reworked old diagram in the middle, to the prototype of the new roadmap on the right.

The world of 2.5D and 3D assembly processes is now a major part of this roadmap, which, this time, focuses on standard semiconductor devices. Note that we will have an expanded pictorial roadmap for the power semiconductor industry and its various verticals - out later this year. 

In trying to produce a simplified version of a complex process, there is always a need to take shortcuts, and the pictorial roadmap is no exception. For example, we know that sometimes zero level interconnect (ZLI), [microbump/copper pillar flip chip to interposer], is done after the first level interconnect (FLI) [interposer to substrate] rather than beforehand, and we understand the reasons why, too! So please forgive us a little artistic license and, as always, we look forward to your comments when the final roadmap goes "live" both on our website, and at our booth (6365, North Hall) at Semicon West 2012.

Cheers!   Andy 

Solder wire is generally used for manual soldering operations, including rework.  But, it can also be used in automated applications such as die-attach soldering.  Solder wire can be flux-cored, or solid with a separate flux used.

Each application can have different requirements for the wire.  For example, wire used in die-attach applications needs tight dimensional tolerances to insure an exact, repeatable amount of solder is deposited each time.  Reduced oxides are also critical to eliminate any "splattering" of the molten solder during the deposition process.

Wire can also be used for non-soldering applications. For example, indium (and indium alloys) wire are often used as a sealing material (particularly in cryogenic sealing applications) - more here) and as a thermal interface / management material.

Decades ago, 0.030" (0.76mm) diameter was the standard size, but today we are able to produce diameters as small as 0.001" (0.025mm) in tin silver (Sn Ag), tin silver copper (SAC) and gold tin (Au Sn) alloys.  Considering that a human hair is about 4X that size, that is a very small diameter!  Pure indium wire is limited to 0.010" (0.254mm), but alloys containing indium can be produced smaller than that.

The wide variety of diameters available in Au Sn make this alloy ideal for the complex applications in medical, aerospace, and other high reliability applications.  However, the Sn Ag and the Sn Ag Cu are used across a variety of standard applications that require lead-free materials.  Sn Ag is particularly good in soldering to Nitinol.

At first look, wire seems like a pretty simple product.  But specifying the right alloy, diameter, tolerances, and packaging can make all the difference.  It can help you achieve a repeatable process that gives you high yields, strong solder joints, and enhanced profitability.  For further information - contact me.

Carol Gowans

For reasons that I will discuss in a post later this year, a common factor that is emerging in the area of copper-pillar microbump 2.5D and 3D joining, is the adoption of thermocompression (TC) bonding for flip-chip flux/microbump soldering. TC bonding is now being predominantly adopted instead of reflow. Some of you may have the same response as I got at iMAPS 2011 from one well-known expert in packaging technology. He looked askance at me when I mentioned TC bonding for flip-chip and retorted: “That’s for bonding wafers, not soldering flip-chips!”. Even good old Wikipedia (at time of writing) seems to have the same problem – basically that the industry usage of the term has moved into the packaging arena.

I spent a little time talking to people in the industry, and on Google, putting together a buyer’s guide for those of you looking at who-is-doing-what in TC bonding. This is just a prototype guide and necessarily incomplete – if I have missed your company out then I apologize, and will add it in: just give me all the details!

Equipment Type	Company Name	URL	Bonding tools	What else they make
Die-bonders	ASM (PT)	http://www.asmpacific.com/asmpt /index.htm	Die bonders, flip-chip bonders	Various others
Die-bonders	BESi	http://besi.com/	Die and flip-chip bonders (Datacon)	Meco (plating systems), Fico (molding / trimming), ESEC
Die-bonders	FineTech	http://www.finetech.de/	Die bonders, flip-chip bonders (offline)	SMT/BGA rework, Laser bar-bonder, VCSEL, Photodiodes, Chip-on-glass, RFID
Die-bonders	Hybond	http://www.hybond.com/	Eutectic die bonders (offline/manual)	Wirebonders / Peg and bar lead diode bonders
Die-bonders	Newport	http://www.newport.com/	Die bonders	Optical and alignment instrumentation, spectrometers
Die-bonders	Palomar	http://palomartechnologies.com/	Die bonders	Ballbonders, stud bumpers, manual die bonders
Die-bonders	Panasonic	http://www.panasonicfa.com/?id=MD-P200	Die bonders	Wirebonders etc etc
Die-bonders	SET	http://www.set-sas.fr/en/	Die bonders, flip-chip bonders	Large device bonders and nano-imprint
Die-bonders	Shibaura	http://www.shibaura.co.jp/e/products/	Die bonders, flip-chip bonders	FEOL products (etching, stripping, coating, jetting) and BEOL
Die-bonders	Toray	http://www.toray-eng.com/sitemap/index.html#semicon	Die bonders, flip-chip bonders	[Semi]Inspection, exposure, encapsulation. COG / COF / FOG bonders
Die-bonders	Westbond	http://westbond.com/machines.htm	Die bonders (offline/manual)	Wirebonders
Wafer bonders	EV Group	http://www.evgroup.com/en	Wafer bonders	Lithography tools
Wafer bonders	Suss Microtech	http://www.suss.com/	Wafer bonders	Mask aligners, nanoimprinters, photomasks, lithography tools

Thanks to Brian Schmaltz of Namics kk for one extra addition to the list. 

Cheers! Andy

Solder starvation is a serious electronics assembly issue - with a very simple solution.

Solder starvation occurs when adequate volumes of solder are not available to effect a perfectly-shaped solder joint. The consequences include:

• weak solder joint strength
• open solder joints
• intermittent short circuits
• reduced first-pass yields
• increased inspection
• increased rework
• field failures
• damage to your company's brand & image
• reduced sales and profits

Frequently, solder starvation occurs in Surface Mount Technology (SMT) when solder paste deposits are inadequate.  This happens because: 

• The single-thickness stencil is designed for the majority of smaller components, starving the few larger components of solder volume.
• High-use interfaces, such as connectors and USB ports, require extra solder - to assure their solder joints survive the constant use in the field.
• Smaller, more tightly compacted circuit boards don't allow for deposition of enough solder paste.

So, how do you solve this increasingly common problem without impacting your process or your cost? 

Solder Fortification® preforms are the simple answer:

• You can add solder just where you need it without overprinting solder paste or working with step stencils.
• Preforms deliver precise, repeatable volumes of solder.
• Preforms can be added during your existing SMT process with existing pick & place equipment.
• Preforms eliminate the need for rework or hand soldering at the end of the process.

For more information, contact me at solderfortification@indium.com or visit our web site at www.indium.com/solderfortification.

Carol Gowans
Market Manager

I recently visited a customer that was doing a lot of hand soldering. I always marvel at the variety of techniques and processes that are developed in an attempt to reduce variability and increase throughput for this very exacting work.

EXAMPLE: assembling connectors
Placing individual solder washers (sometimes quite small) can be very time consuming.  It is also very easy to either place too many washers or not enough and not detect the problem before it comes back at rework.

Take a look at this video that shows the difference between placing individual solder preforms and InTEGRATED® Solder Preforms.

A single placement of an InTEGRATED® Solder Preform improves your throughput and accuracy in one motion. This goes directly to your bottom line.

If you would like more information on this ingenious product, check out InTEGRATED® Preforms or contact us at askus@indium.com.

The "wave soldering flux deactivation temperature question" arises every few weeks, and the easy answer is that wave solder fluxes are designed to see the temperature of the wave.

Now, in order to pass SIR testing, the test boards with the wave fluxes are sent through the wave pattern up, not in direct contact with the molten alloy. They still see the majority of the heat from the wave.

The “deactivation” temperature varies from process to process because of the differences in board complexity, flux application, and preheat, as it is really a matter of total energy input, rather than a specific temperature.

The potential for reduced SIR is the main issue, not necessarily ECM or corrosion.  With a rosin-free flux, there may be some visual clues, as well. If you see that the flux has dried to a white, powdery residue that may be a sign that it had not seen temperatures.

We get this question mostly from corporations that believe they can use the same flux formulation for wave soldering and hand assembly / rework. Wave fluxes are not designed for hand soldering, and will more than likely cause some sort of downstream issue if used as such.

Feel free to ask me any questions about your process!  From One Engineer To Another!

I just received a customer inquiry regarding a phenomenon that is little studied and even less quantified; “How many times can I reflow a solder alloy before damaging the solder joint?”

As you may already know, each time you bring a solder alloy above its liquidus temperature, it continues to dissolve the metallizations on the substrate to which you are soldering, as well as the metallizations on the leads of the component being attached. With modern processes, a 3-time “excursion” is common, especially with double-sided reflow and rework. Typically, the solder applied with paste is not reflowed again during the wave, because, through the use of pallets or selective soldering, it doesn't get quite hot enough to melt. That said, in such a case, the solder joint may become hot enough to receive some damage. To me, the most interesting thing with crystalline intermetallic layers, is that they don’t need to reach liquidus to form larger crystals. So a temperature excursion close to the liquidus may also increase the crystal structure size.

Another factor is surface metallizations, especially easy-to-solder surfaces such as gold or HASL. With gold, molten Sn/Pb solder at 200°C will dissolve at 35u-inch/s. So, a fine flash layer, such as 3-5u-inch, is gone within the first second, and the actual intermetallic is formed to the underlayment; most commonly nickel (Ni). This is similar with HASL, as the HASL layer is consumed into the solder joint at liquidus, and the intermetallic layer is formed with what is beneath the HASL.

The intermetallic layer will increase with time above liquidus (TAL) and also with temperature, with hotter dissolving more of the surface. This is why there are operating temperature limitations on the final solder joint, such as no more than 90% of the solidus of the alloy, in degrees Kelvin.

Another factor that affects grain structure, besides TAL and peak temperature, is cool-down rate. A faster cool-down rate will form a smaller crystalline grain structure, but keep in mind that a too-fast cool down rate may result in stresses being trapped in the grain structure from the CTE mismatch between the component and the substrate.

It has been our experience that 3 temperature excursions is the accepted limit (by most companies that I work). But, the only recommendation that we can offer is that you try “worst-case” scenarios, and have ALT testing and SEM cross-sections performed on real-world products in which 3, 4, and 5 excursions have taken place. Your particular case may be unique - it is well-worth determining your particular situation.

Integrated® Preforms are connected units of solder that can be placed in an application to provide the sole solder for the joint. They can also be used to add to the volume of solder, when used in conjunction with solder paste - to fortify the joint. Integrated Preforms are available in most alloys that are currently incorporated in common solder pastes.

 

The only difference between connected preforms and separate preforms is that the Integrated (connected) Preforms are attached to one another and can be placed in the application as one multiple unit of solder. Connecting each individual solder preform is a small strand of solder that is designed so narrow that it will separate during reflow (to prevent bridging).

 

When manually reworking boards to add additional solder to joints becomes too large of a task, Integrated Preforms can be incorporated prior to reflow so any rework is not necessary. In through-hole applications, the connected preform can be placed on the component and then inserted into the holes of the board that have solder paste placed on top of them. There is no need to flux the Integrated Preform because the flux vehicle in the paste will provide the fluxing.

 

When used as a stand-alone connected preform, or with solder paste to fortify the joint, Integrated Preforms can be reflowed using the same temperatures and profiles as for the paste by itself.

 

To learn more about Integrated Preforms and solder fortification®, plan to attend the presentation of a paper on this topic at Apex 2011 (Las Vegas, NV, 10-14 April) given by Dr. Ronald C. Lasky (see sidebar →), Indium Corporation Sr. Technologist and Instructional Professor, Thayer School of Engineering, Dartmouth College.

 

The next post in this series will address the various shapes of Integrated Preforms and how they are packaged.

Thermal News recently interviewed Amanda Hartnett regarding thermal management with metal TIM (thermal interface materials). You can read the full article here:

http://www.thermalnews.com/eprints/Indium_0310.html

 

I really like this interview, so I’m not going to give away the best parts – I want you to read it yourself. I do, however, want to provide a couple teasers to pique your interest. I’m leaving out the especially cool parts…

 

“Pure indium, used as a solder TIM, delivers a thermal resistance to…”

 

“Also, it is important to consider the reworkability of an interface material. TIMs such as … are very simple to rework. Others, such as conductive epoxies, can be quite difficult.”

 

“When I measure the performance of thermal interface materials, I characterize them based on ... This value is typically more valuable than bulk thermal conductivity. For a compressible TIM, the … assumes the actual contact which will be made between the interface material and it’s mating surfaces. This provides a measurement of thermal performance which is as close to real-world per Watt or per cm2 as I can provide without being application-specific.”

 

Are you still reading this blog? Go read the article!

 

~Jim

I love watching a good basketball game, and one of my favorite local teams is the Syracuse Orangemen. If you go to a Syracuse home game, notice the shot clock – it was made with Indium Corporation solder. There are a lot of places you can see our products in your everyday life. That smart phone in your pocket, the electrical components in your car, the thermal interface in the computer in front of you. That’s one of the things that makes this job rewarding, being part of so many various applications.

 

In addition to learning about these different applications, we also get a good reference for what assembly trends are developing, and which material technologies are becoming more popular. 

 

I’ve watched the halogen-free trend explode and fade, as it was adopted by some large OEMs and their contract manufacturers, but has not spread to most other companies. Another trend that is fading away from the spotlight is Pb-free die-attach solder, since the EU has not found a suitable replacement and has pushed back the exemption deadline. 

 

A long-existing topic that has had recent mention is solder jetting. The trend towards soldering smaller components is not new or surprising, but for smaller components (01005s and 0201s) we have seen a trend towards dispensing instead of jetting – which seems to suit those applications.

 

For small component printing, transfer efficiency is critical. Outside of solder paste optimization, “nano-stencil” technology is an upcoming technology that may take-off and improve paste release characteristics. Solder paste is being used in some other creative ways too, like low temperature alloy dipping paste for rework operations. Manycompanies are now using or evaluating specialized solder applications to replace components without fully reflowing the rest of the components on the board.

 

Integrated preforms are finding their way into more and more applications recently as well. These connected preforms are being used to reduce the need for component pallets and selective soldering operations.

All these applications are great ways that our customers are taking soldering technology to the next level, using materials and assembly methods that were not common before. I look forward to learning how you’d like to use solder in your application!

Folks,

Every so often a new electronics assembly technology comes along, and I am asked my opinion about it. The latest “new” technology for assembly is RF Activated “Green” Nano Solder.

My response when asked about this follows:

“I think Intel's caveat in the article tells it all:
 
‘Intel cautioned, however, that several engineering refinements need to be made before the new RF soldering method can be used commercially.’

 
Interpretation: This puppy needs $20 million of R&D before it is ready.
 
Nano solders have been studied for years.  They are interesting and have promise, but there are big hurdles.
 
People will say they want an exciting new technology like this, until that find that the soldering material costs much more than their current one, they need new equipment, etc.  All of the sudden today's process (disappointments included) doesn't look so bad.  It is hard to replace an incumbent process unless there is a strong need - and typically it must be at equal or lower cost.  These will be challenges for this proposed process.
 
So my take is, it is interesting process science, but let's wait awhile to see more data, prototypes and cost estimates before we get too excited.

Any new technology process must be evaluated under the following criteria:

1.     If “disruptive”, it must meet an overwhelming need. E.g.: If your process has a 95% first pass yield and the 5% of the product that is repaired only cost a small amount, you will be unlikely to want to take a chance on a new, unproven technology when the time comes to invest money in it.

2.     The new technology’s implementation must have a minimum of disruption, if implemented in a current process and the cost must be equal or less than today’s process. E.g.: You want to improve your process in #1, however if the new process requires radically new equipment and/or materials you will be hesitant to adopt it.

3.     The process will need several years to prove itself. You know the problems with today’s process, but what are the problems with the new process? You will likely want yield and reliability data. These requirements will take some time.

4.     You must consider the improvements in the old process. Often a new process will aim at where the old process is today, not recognizing that the old process is often improving by the time the new process is implemented.

Using these criteria, let’s look at the implementation of SMT technology in the age of through-hole (TH), circa 1980. How did it measure up to these four criteria?:

1.     SMT met an overwhelming need. One simply could not design a small, high performance personal product, like a mobile phone, with TH.

2.     SMT lines evolved from TH lines, sometimes with radical changes, but the need overwhelmed any disruption.

3.     Much work was performed on SMT products to demonstrate that reliability was acceptable.

4.     The need for SMT was so great that TH's "future" was not an issue.

Contrast this situation to the SMT process discussed above (that has 95% first pass yield) with the 5% fallout reworkable. It becomes difficult to envision making any “disruptive” change to a process like this…..it just won’t pay financially or in any other way.

Your comments?

Dr. Ron

 

Patty, Pete, and John prepare to do battle with "The Big O."

Patty and Pete were able to squeeze in 9 holes of golf, though it was really stressful for Patty. Pete was a good golfer, but not in Patty’s league; he typically shot in the low 80s for 18 holes compared to Patty’s 68-72 range.   Today, going into the 9^th hole, Patty was even par and Pete was one under. He was teasing her relentlessly.   The ninth hole was 532 yards long. Patty used all of her recent training and focused as she drove the ball. Her swing speed hit 114 mph and with a 4 mile an hour tailwind, her drive was 291 yards, 30 yards beyond Pete. Her second shot, with a five wood was 12 feet from the pin. Her putt was dead center for an eagle, Pete’s 8 foot birdie putt lipped out of the hole. Whew! She beat Pete by one stroke! Pete was still thrilled that he gave Patty such a close call.

As they left the golf course, Pete said, “John is really working miracles at the factory, given the constraints he is working under. He has developed a disciplined approach to changeovers and uptime, and has eliminated most waste. But the factory really needs to be cleaner and more organized. With all that is on his plate, and no cleaning staff, he will have trouble implementing a 5S. It will be hard to win new customers with the place looking like it does.”

The next morning, as they prepared for the meeting with Oscar Patterson, Patty noticed that John’s color was ashen.

“John, are you alright?” Patty asked.

 “You’ve never been in a meeting with Mr. Patterson. He can be a bit…uh…. difficult,” John stumbled out.

“From what I hear he is a ruthless, brutal dictator,” Pete added.

John did not disagree.

Patty thought it might be best to call back to her site GM to clarify her mission.

The GM told her, “This guy is a blowhard, it would be great if you could review with him your findings and get his buy-in. But, don’t take any grief from him. He forgets that he sold us his company. Now he has a boss, and it is me. I told him you were going to perform an audit and I want him to work with you.”

So Patty, John, and Pete went to Oscar Patterson’s office to review their findings. Patty was immediately intimidated by him. He was a huge man with a ponderous stomach. But the posters in his office were the worst. One read “I’m the Boss, you aren’t.” Another read, “My way or the highway.” Then she saw, “The Golden Rule of Management: Whoever has the gold makes the rules.” The last one she took time to read was especially troubling: “It’s a question of mind over matter: I don’t mind and you don’t matter.”

Patterson spoke first, “Let’s get this over with, I don’t have time to waste on this nonsense. I’m the boss and I’m responsible for profits, so give me your crap and get out of here.”

The Professor always advised Patty that after an audit it is best to present the strengths first and then the problems. However, never call the problems “problems,” call them “opportunities for improvement.”  “I learned this from my colleague Joe Belmonte,” The Professor told her. She had since met Joe at a few trade shows and was impressed by his wealth of experience and in-depth knowledge of assembly processes.

She started by discussing the very good 25% uptime, and the fact that the operators were quite good at changeovers.  Pete had pointed out that the operators told him that John was responsible for both of these successes. The operators liked and respected John, but realized he had a tough job working for Patterson.

As imagined, Patterson warmed up to this compliments. 

“I told ACME management that buying my company was a good deal. We cut costs and I am able to make a profit even though I have losers like John working for me,” Patterson bragged.

Patty was furious at this comment. Pete looked like he was going to jump across the table and take a swipe at the “Big O.” John just sat there looking defeated.

“This isn’t as bad as I thought it would be,” boomed Patterson. “Continue.”

Patty then reviewed the 7 mudas. She had been surprised that the company did quite well in this part of the audit also, undoubtedly attributed to John:

1. Overproduction

2. Unnecessary transportation

3. Inventory

4. Motion

5. Defects

6. Over-Processing

7. Waiting

Hence, Patty’s comments were positive on this topic.

“You'se guys aren’t so bad,” boomed Patterson. “I told you I was good at generating profits, even stuck with a dufus like John here,” he finished.

At that comment, Pete’s faced turned the most crimson Patty had ever seen.

Patty then went on to “Opportunities for Improvement.” She thought she would start with 5S.

“We performed a “5S” audit of your facility. This manufacturing philosophy consists of:

1.       Sorting

2.       Set in Order

3.       Shining

4.       Standardizing

5.       Sustaining the Improvements,” she started.

“As ACME strives to get more customers for our contract manufacturing services, 5S is an important consideration, as many of our current and future customers practice Lean and especially 5S at their facilities,” Patty added.

As she went on she reviewed the lack of order and cleanliness in the facility. She had photos of dried solder paste on the stencil printers, the flux and dust “stalactites”, and several other examples of 5S violations. Patterson’s face soon matched Pete’s in its level of sanguinity. But he said nothing.

Patty then volunteered that she and Pete would work with John and his team to implement a 5S if desired.

Patty could see Patterson was ready to blow, but she felt she must go on. The only topic left was turning off the nitrogen in the wave soldering machine.  As Patty played the wave soldering video, surprisingly, Patterson seemed interested. 

She continued, “We think an opportunity for improvement would be to re-instate the use of nitrogen in the wave soldering process. First pass yields have dropped from 94% to 87%, thus increasing re-work. Or, perhaps, implementing a more robust wave solder flux. I contacted a wave flux vendor and I have some recommendations.”

At this Patterson became even redder in the face, in a rage he grabbed Patty’s laptop and threw it on the floor, instinctively Pete dove for the laptop, spun around and inserted his chest between it and the floor.  Patty had never seen such agility in a 45 year old man.

“You bozos are worse than John the clown here!" he shouted, as he gesticulated toward John. 

Patterson then kicked the trio out of his office. Pete was ready for a fight, but John and Patty, both visibly shaken, held him back.

Patty immediately called Sam, her GM, and told him in detail their findings and what happened at the meeting. She gave a good impression of what John had accomplished in spite of Oscar Patterson.

“Wow! Patty, I’m so sorry. I didn’t expect it would be this bad. I’ll change my schedule and fly there today. This situation will not stand. Why don’t you and Pete take a break and meet me for dinner at Dinardos at 7PM? Bring John with you.”

Patty was glad that she backed up her files last night on SugarSynch, even though it looked like her laptop was fine. 

Colonial Williamsburg was only a 45 minute drive away, and it was just 10AM. Taking Sam’s advice to “take a break,” she and Pete drove away and toured this beautiful living museum. They also had lunch at the Trellis.

Surprisingly, with the Williamsburg respite and all of the walking Pete and Patty did, they were more relaxed and hungry than they thought they would be. 

On the way back to Dinardo’s Patty asked Pete, “How did you save my laptop, I’ve never seen such an agile, athletic move?”

“Twenty-nine years of beach volleyball,” Pete answered.  “I was good enough that I tried out for the Olympics  in ’92. Humbling experience,” he added.

About 10 minutes before they arrived at the restuarant, Patty's mother called with updates on the wedding plans.....only 10 weeks and counting!

John had arrived early at the restaurant and Patty and Pete met him. He looked very nervous. 

“John, how’s it going?” asked Pete.

“It’s hard to be optimistic,” John answered.

On that note Sam walked into the restaurant.

“This must be John Davis, the new GM, having replaced Oscar Patterson,” Sam stated with great cheer.

These words didn’t seem to register with John.

“Congratulations John, well deserved,” Patty and Pete chimed in.

In the few days they were there, Patty and Pete had grown quite close to John.

As the information sank in, tears welled up in John’s eyes.

“Do you think I’m up to the job?” he asked.

“John, you are already doing the job,” Patty answered.

Epilogue:

Sam had felt it best to have the police accompany him to see Oscar Patterson with the news that he was fired. Patterson became so agitated that the police had to threaten to arrest him before he calmed down and was escorted out of the facility.

With John at the helm, the “shop” was not recognizable in 3 weeks, as he implemented a 5S program that he designed with Patty and Pete.

He performed some DOEs to find a wave solder flux that could perform well, without nitrogen, for most of his applications. However, he still used nitrogen for a few boards that had a large thermal mass. All of these, and the many other, decisions he made were data driven.

Have you performed a Lean audit of your facility? Do you regularly practice 5S and look to eliminate the 7 mudas? Are your decisions “data driven” as John’s are?

Cheers,

Dr. Ron

Note:  The golf photo is from: http://www.flickr.com/photos/gusilu/2785690627/sizes/l/#cc_license.

The "mudas" image is from: http://www.vision-lean.com/wp-content/uploads/2008/06/muda.png

Conductive epoxy is a common material choice for bonding components, especially if the assembly process is temperature-sensitive. Tin-based solder paste or preforms with flux are preferred Pb-free bonding materials; however, conductive epoxies arguably provide advantages over these traditional solder assembly materials. 

 

It has been my experience that these advantages are perceived in the absence of an awareness of the full solder assembly materials product offering. Specialty solders can provide the same advantages as conductive epoxies and then some.   

 

Some claimed advantages to conductive epoxies include:

·         RoHS-compliance

·         Ease of assembly

·         No-clean

·         Low cure temperatures

 

Low-temperature solders such as 58Bi42Sn and 52In48Sn are specialty low-temperature solders which have these same properties including processing temperatures below 150ºC. Both of the referenced alloys are Pb-free, can-be used with no-clean fluxes and are assembled using the traditional solder assembly techniques.

 

It would seem a toss-up between whether to use a conductive epoxy or specialty solder to assemble temperature-sensitive components except that there are additional advantages to a soldered assembly as compared with an epoxy-assembly. These include:

 

·         Thermal cycling reliability

·         Solder material consistency

·         Reworkability

·         Thermal Conductivity

Click here for a description and video that shows a nozzle design from FINETECH  which clamps down onto PoP components during rework. 

 

“The PoP soldering head is an easy-to-use tool for reworking stacked devices as a whole in a single reflow process. It uses vacuum-actuated mechanical clamping tweezers which avoid separating the single layers of a PoP during component removal. The PoP soldering head can be easily adapted to different component thicknesses. Furthermore it is possible to adjust the width of the clamping tweezers prior to the process when the rework arm is swiveled down to avoid affecting other components on the PCB (e.g. accidental shifting of neighboring small passives).”

 

Sounds like this would be great for combating “PoP Quicksand”. That nasty problem that large components have when the vacuum provided by the nozzle isn’t strong enough to lift the package-on-package component back out of the PoP solder paste or dipping flux. Okay, I just made up that term – but it’s pretty descriptive, right?

 

Conceptually it seems to make a lot of sense, please comment if you have any experience with it!

7:40am

Just got in, fired up the laptop, and made some hot chocolate. This is the best time to get a jump on the day. I clear out my spam that rolled in overnight and prioritize the emails in my inbox. The first tasks that I cleared were:

-         Connected a new potential solar materials rep with the right people at Indium Corporation

-         Recommended the optimal reflow profile for Indium9.88HF PoP solder paste

-         Activated an online Vapor Deposition course

-         Helped specify tabbing ribbon and solder wire for a college student working on a lunar rover project

-         Planned underfill testing for today.

 

10:00am

After rounding up materials, components, and equipment, Brandon Judd and I assembled some BGAs on a customer's test board. Later today we’ll underfill, and rework some of the components to demonstrate the yield of a reworkable underfill. Each board had 18 components of 2 types. One of them is a very large, coarse pitch BGA. The other one (you guessed it) is exactly the opposite, a small, fine pitch BGA.

 

Noon

Took a drive and ate lunch.

 

1:00pm

When I returned to my desk, I noticed a few emails that needed attention. One was regarding the PoP solder paste reflow profile I mentioned earlier. It looks like that will work for the particular application. Another email regarded a barcode design that I am working on for a customer.

 

1:30pm

Took a call regarding solder sphere attachment. WS3622 was recommended to ease flux cleaning in place of an older tacky flux.

 

2:00pm

Answered an interesting call regarding thermal management for a cavity CPV assembly. The coolest part – he found my contact information on this blog.   

 

2:45pm

Worked on editing an interview for Global Solar Technology magazine. I had a chance to discuss many of our solar products in detail, while explaining the advantages of each.

 

3:00pm

The schedule for the day shifted, so we will reconvene the underfill testing early next week.  This gives me some time to begin the Interfacial Engineering course mentioned earlier. Looks pretty interesting so far.  Spent some time going through the course material and learning some new things.

 

4:30pm

Posted this blog entry. After looking at the things I’ve mentioned here, I noticed I could tweet all the little parts of my day. If you’re interested, check: http://twitter.com/SolderNinja

There is nothing more frustrating than going through an entire process (whether it is putting together a puzzle or manufacturing a product) only to find the final piece missing. 

That final piece can be the strength of the solder joints which can impact the quality of your product or the amount of rework that needs to be done.  As the products get smaller and the solder paste stencils get thinner, the ability to get enough solder paste to adequately hold shields, components and connectors gets harder and harder.

So what is that final piece of the puzzle?  Consider Solder Fortification® Preforms.  These are solder preforms, which are solid pieces of solder, that are added to a solder paste deposit to give it the additional volume required to create a stronger joint.  They generally come in sizes similar to components, such as 0402 and 0603, and are packaged in tape & reel like the components so they are easily placed with standard pick and place equipment.

The additional solder can improve your first past yields and reduce field failures.  Now that is the perfect final piece to complete the picture!

This is one the best BGA rework tutorials I’ve seen so far.  I’m a sucker for video tutorials and these videos do a pretty good job of showing the solder joint during each operation.  If you’ve ever wanted a visual description of the difference between rework in air or nitrogen, this is for you.

In an earlier post, I mentioned how hard it was to get technical support from some equipment vendors.  In response to that, Ed Zamborsky (OK International) not only offered technical support, but offered to help answer some of my questions for this blog post.  Cool!

 

So here is my question: Which iron tips should our customers use for non-standard alloys?  I’m interested in 52In/48Sn, 58Bi/42Sn, 100%In, and 92.5Pb/5Sn/2.5Ag…

 

Ed: “So much of the tip temperature is dependent upon the target PCB area as well as the mass of the components being soldered. Using a Smartheat soldering system I would suggest the following cartridges for our different systems:

 

Solder Melt Temperature                         MX Series      PS Series       MFR Series

52In/48Sn (118degC melt)                      500 Series     T Series        T Series

58Bi/42Sn (138degC melt)                       500 Series     T Series        T Series

In (157degC melt)                                 600 Series     F Series        F Series

92.5Pb/5Sn/2.5Ag (287degC melt)            600 Series     F series         F Series

 

On a heavy substrate or ground plane, you can always select the next higher temperature series to optimize the hand soldering process.“
 
Ed also guided me to a collection of technical videos that he helps put together to assit customers during selection, testing, and use of his company's products - which include rework and dispensing equipment. 

Ed Zamborsky is a product manager for OK International, he can be reached at:

ezamborsky@okinternational.com

386 846 5647

I just met Ed, but I have a feeling he is a solder ninja just like me...

This is a blog post about a great post that may never be...

Unless a solder iron vendor wants to step up and declare that they offer technical support.

The idea was simple enough, contact a soldering iron vendor and see what temperatures they recommend for certain non-standard (Sn/Pb or Pb free) solder alloys.  To promote the knowledge that these technicians have, and to show that you need to have a much higher tip temperature than you would for a furnace peak reflow temperature.  Hand soldering seems like an area that would be interesting to share with our readers.  We could talk about rework solder defects, new products, and tricks for those of us that want to be better at hand soldering.

The plan was to just get in touch with the top companies that make soldering irons (ahem, no names need to be mentioned...) and at least ask them if they were interested in participating.  I quickly learned - you can't just contact them!  The only way I found to ask for help from one of the big name in hand soldering is to plead for help on their inquiry system.  This system is nameless, faceless, and traceless - forget about an email to help you know who you are talking to.  I think I was speaking to a black hole, because I still have no response after around 2-3 months. 

Of course, I wanted to be ready incase they didn't want to help, so I tried to go down the list and ask a few other hand soldering equipment vendors for collaboration.  I learned that not responding must be a trait for these companies, and that the iceburg in the title of this post isn't the only cold thing about the story.   

If you are a soldering iron vendor, representative, or user who does get the help you need, please prove me wrong.  Comment, email me, or help me write the great post that may otherwise never be!