Halogen-Free Materials for Electronics Assembly

As more individual halogenated compounds become restricted, it becomes more and more likely that electronics companies will just restrict ALL halogenated compounds.  The reason is that it is very costly to test for specific compounds but there are low cost tests to look at the elemental level (i.e. look for Cl and Br).

Recently, the European Chemical Agency (ECHA) has recommended that hexabromocyclododecane (HBCDD) be included in Annex XIV of the REACH legislation.  Once a material is placed in Annex XIV, it will be banned from the European Union within 3.5 - 4 years.  It is likely that HBCDD will also be added to the next revision of the RoHS Directive.

If you are like me, when you hear the term "whammy" you think back to the 80's game show called Press Your Luck.  The electronics assembly industry is converging on what I like to call the triple whammy.  This would be very bad if you were playing Press Your Luck, but for us it is really the result of innovation and environmental movements.

The triple whammy in electronics is the convergence of two environmental (and legislative) movements combined with the continued advancement in electronics functionality.  Those three things are:

• Pb-Free: Many assemblers have already made this transition while others are just beginning this process.  Pb-Free alloys have higher melting points, poorer soldering characteristics, and, in some cases, decreased reliability.
• Halogen-Free: This transition is just beginning and has a dramatic impact on PCBs, cables, and soldering fluxes and pastes.
• Miniaturization: As the technology improves, we are putting more functionality into smaller devices.  This means that the PCB assembly process becomes much more challenging with tiny components and thin boards.

From an assembly perspective, the triple whammy means that we all need to focus being very diligent in selecting the best materials (PCB's, components, soldering materials) to do the job.  In addition, process optimization will have a dramatic effect on yields.

In the spirit of Press Your Luck, we need to use engineering and process expertise to ensure the whammies don't take us out of the game and we can all reap the "Big Bucks!"

Shhhh.  Don't tell anyone but I have a secret.  The activators used in halogen-free solder pastes aren't as effective as their halogen contained counterparts.  The real secret is coming up with a technology that overcomes the deficiency.  Indium Corporation's approach to this has been to focus on the oxidation barrier of the solder paste.  The theory here is that if you can prevent oxidation from occurring through the preheat and soak stages of the reflow process, then the activators have to work less to remove oxides.  Indium Corporation used this approach in developing the Indium8.9HF solder paste.  This solder paste clearly outperforms most solder pastes in reducing head-in-pillow and graping defects by preventing oxidation.

The question often arises as to whether or not a water wash solder paste should be halogen-free.  Since halogen-free is fundimentally an environmental issue, the key concern is all the materials that remain on the PCB when it is in the finished product.  Since the flux residue of a water wash solder paste needs to be cleaned after processing, there should be no residue remaining on the board.

I have also heard comments such as: "I need a halogen-free water wash solder paste because I don't want to risk halogen presence on the board if I don't end up properly cleaning it."   The issue here is that improperly cleaning a water wash paste is actually an electrical reliability issue (regardless of whether or not it contains halogens).  That residue remaining has a good chance of promoting corrosion and dendritic growth.  Making a halogen-free decision based on a lack of confidence in your process doesn't make sense to me!

Indium Corporation is a big proponant of using the EN14582 oxygen bomb test method for halogen determination.  However, we have seen misleading reports from major test labs when using this test method for solder pastes.  Since the industry is concerned about what remains on the final electronics device when consumers receive it, testing of solder pastes should look at the material that remains on the board after assembly.  Here are some basic facts about solder paste to make my point clearer:

• Halogens would only be present in the flux portion of solder pastes
• Pb-Free solder paste is approximately 89% metal and 11% flux (by weight)
• During the reflow process, approximately 50-60% of the flux volatilizes

Why are these points important?  What I am seeing more and more often is the oxygen bomb report on the solder paste when the flux residue is clearly what is important.  If the report shows that a solder paste has no halogens detected (N/D), it still could be in violation of what the electronics companies want.  Let's assume that in solder paste form, the actual halogen content was 50 ppm of Br (which would often be N/D due to equipment capabilities).   Since the halogen is coming from the flux, that means we have 455 ppm of Br in the flux (50/11%) .  During reflow, let's assume that 60% of the flux volatilizes.  Very little, if any, of the halogen is part of that volatile constituant.  Therefore, if there was 455 ppm of Br before reflow, there will be about 1137 ppm of Br in the flux residue (455/40%).  This is higher than the 1000 ppm allowable maximum recommended by the J-STD-709.

Therefore, it is unacceptable to test solder paste for halogen content.  Even if there is no halogen detected in the solder paste, the flux residue still could be above the acceptable limit.  Be sure the solder paste vendor is at least testing the flux (if not the flux residue).

One of the common reasons for halogen elimination in electronics is based around the possibility that halogens can form dioxins when that halogenated product is burned. Dioxins are considered to be likely carcinogens. During uncontrolled incineration, the dioxins can be breathed in by any person or animal in close proximity to the fire. In a photograph published last year by National Geographic (shown here), you can see an indivdual in India buring the insulation off of copper wires in an open pit. Copper has value, but most companies won't buy back copper with the insulation on them. Therefore, this individual has decided the easiest way is to just burn it off. The wires most likely have PVC coatings on the outside which does contain the halogen chlorine. By buring the halogenated wires, this person is putting his own life and others nearby at risk. I can't find the source right now, but it was documented that about 40% of dioxins in the air are a result of "backyard" or open pit burning of materials. My personal opinion is that we can eliminate the halogens to reduce dioxin formation, but does that really make these types of burning practices "safe?" I don't think so...

First, I would like to give some key HD advice: When I bought my DLP TV two years ago, I didn’t think that I would need more than one HDMI port. If you buy one, make sure there are at least 3 HDMI inputs.

Since I am not ready to buy a new TV, I bought a Sony receiver that will accept 3 HDMI inputs and send them out of the receiver on a single line (to my TV). Now I can connect my cable box, DVD player, and computer to the TV. What I didn’t expect is that I would be helping the environment while doing this. Check out the top of the Sony receiver box. The PWB contains no halogenated materials.

As I crank up the volume on some Hollywood blockbuster, I can relax with my tub of popcorn knowing that the world is a better place because of my purchase. It was a difficult sacrifice, but one that I am glad I made!

This is the first I have seen halogen-free advertised on outer packaging of electronics.

In a CNN article today, it is reported that Ireland found “alarmingly high levels of dioxins” in their pork. Dioxins are a known carcinogen. One source of dioxin formation is the incineration certain halogenated printed circuit boards. This is the primary reason electronics companies are targeting halogen-free for their products.

I am willing to bet that NGO’s (such as Greenpeace) will use this report as further ammunition as they push the electronics industry to eliminate using halogens such as Cl and Br. When the general media starts reporting on halogens and dioxins and increases the public awareness, it becomes difficult for electronics companies not to eliminate the halogens even if the halogenated compounds they are using are not capable of forming dioxin during incineration. Therefore, the more the public becomes aware of dioxins and how they relate to halogens, the more quickly our industry will need to seek to eliminate them.

The environmental push of companies toward halogen-free is driven by environmental organizations such a Greenpeace providing examples of poor recycling conditions in 3rd world countries. One such example is a report by Greenpeace in which they assess the e-waste being burned in Ghana.

The report addresses a serious problem of dangerous recycling conditions and child labor that is occuring in Ghana. The issue that I have is they are focusing on the elimination of hazardous materials as the key solution to the problem. Regardless of whether or not the materials being burned are hazardous, having children working around open fire pits will never be safe. In addition, smoke inhilation can be a health problem even without PVC and brominated flame retardants.

The large electronics companies (Philips is being targeted hare by Greenpeace), are not the ones actually shipping the e-waste to Ghana. I would like to see someone trace the e-waste backward and find out the companies that are profiting by shipping the waste here. What about targeting people/companies who are buying the reclaimed metal from these people in Ghana?

I think that if you want to stop countries like Ghana from using bad practices to recycle and reclaim metals, then you need to target those profiting by shipping waste to them in the first place and those saving money by purchasing low cost metals from these scrap yards.

Much of the environmental push toward elimination of halogens is actually NGOs (such as Greenpeace) requesting that the large electronics companies eliminate BFR’s, CFR’s, and PVC among other potentially toxic materials. Therefore, to comply with the environmental push, halogen-free actually means BFR-, CFR-, and PVC-free.

On the surface, this seems to be easier for an electronics company. Instead of eliminating all halogens, they only have to eliminate 3 categories of halogen. The reality though is that it could actually mean more work for them. There is no reasonable test method to detect BFR, CFR, and PVC in a material. What companies will do is test each article (or component) for presence of Cl and Br. If there is no Br or Cl, they can confidently state that article is free of BFR, CFR, and PVC. The problem arises if there is Br or Cl present. How can they figure out and confidently state that Cl and Br is NOT from a BFR, CFR, or PVC? Without spending tens of thousands of dollars, they can’t.

Even though companies are targeting BFR, CFR, and PVC-free electronics, the reality is that they will actually be forced to go completely halogen-free. The resulting trend is toward completely halogen-free electronics.