-
Hot Air Pencils - what they are and what they can do for you. By Fraser
Posted by Fraser on 15 Sep, 2016 14:15 -
Hot Air Pencils
Many of you, dear readers, will be familiar with hot air stations and their associated hot air hand-pieces.
They work on a very simple principle. Air pressure is created by a diaphragm pump, fan or turbine. The air is pushed past a heating element before exiting the hand piece barrel and being directed to the work piece via a suitable nozzle. There are many different nozzle types to suit different tasks. These include BGA rework and differing sizes of SMT components down to the smallest parts.
Air flow and temperature is controllable by the user to suit the components being heated. Too much air flow can literally blow components off of the PCB. The temperature is set, just as with a soldering iron, to that suitable for the size of component and its heat absorption capability.
Now that we have got the basics out of the way, what is a hot air pencil ?
The name describes this tool well but some are larger and fatter than others so less 'pencil' like ! The operating principle is the same as a conventional large hot air station and hand-piece. The difference comes in the precision nature of the hot air pencil when compared to its bigger 'generalist' brothers.
A hot air pencil receives pressurised air from a station that usually contains a piston or diaphragm pump. The pump has to cope with small hose and nozzle diameters without problems. The pressurised air usually passes through the pencil hand-piece and into a heating element barrel that looks similar to that of a soldering iron. It is thin but, importantly, hollow so that air can pass down its centre. In the end of the heater barrel there is a very small diameter air nozzle from which the heated air emerges.
The diameter of the hot air nozzle and its associated hot air jet is the advantage that the hot air pencil has over its bigger brothers. Nozzles of 1.2mm internal diameter are common. It is not normally possible to use such small diameter nozzles on conventional large hot air station hand-pieces as the heater can suffer low air flow over heating and failure.
Why use a hot air pencil with such a small hot air jet diameter?
Modern SMT PCB's can be densely populated with the smaller sizes of SMT components such as 0603 and 0402. These components are positioned so closely together that great care is needed when carrying out soldering or rework on the PCB. Some equipment contains IC's that are known to be very sensitive to overheating and you do not want to blast them with hot air if you can avoid it.
The hot air pencil is a precision tool whereas the conventional and larger hot air hand-piece is a somewhat more blunt tool, with less precision and control over the hot air stream confinement.
I 'made do' with my general-use hot air station when working on SMT PCB's for some time. I stumbled upon a hot air pencil on eBay and took a chance on it. As soon as I started using it I realised just how useful such a precision tool really is. I have not looked back since. I still use conventional hot air stations but where I need to have greater control over what is, and is not, heated, I always reach for a hot air pencil. I have worked on 0402 SMT resistors and capacitors with ease thanks to the finely focused air jet and adjustable air flow. When working on high density 0402 PCB's I have found the hot air pencil truly invaluable. It also performs well on many other sizes of SMT components and even multi pin SMT IC's. With a hot air pencil you can even rework individual pins on an IC without reflowing the whole IC in the process. You do need to consider thermal differential across the IC wen doing so however as some IC's do not like this reflow approach.
Does a hot air pencil have limitations when compared to a conventional hot air hand-piece ?
Absolutely ! The hot air pencil produces a very fine jet of hot air and, as with a soldering iron tip, you need the appropriate size end piece for the task. The hot air pencil is brilliant on small SMT components but it cannot cope with long multi pin connectors, large SMT components such as power inductors and larger multi-pin IC's.
Large components tend to absorb the heat more quickly and the fine air jet has to be moved back and forth along multi pin parts rather than the broader hot air stream from conventional hot air pieces that heats many pins at once.
Would I recommend adding a hot air pencil to your workbench ?
If you already have the larger type of hot air hand-piece, yes. The hot air pencil cannot replace a conventional larger hot air hand-piece, but it is a valuable addition to the tool arsenal. Just like a fine soldering iron for 'micro-soldering'.
Which are the best brands of hot air pencil ?
This is a difficult question as hot air pencils are not as common as conventional hot air hand-pieces and so there is less choice. Just as with soldering irons, the selection process is very much personal choice. Be it hand-piece design or affordability. Hot air pencils do tend to be expensive, both new or used.
I own several hot air pencils that I have bought over the years. As with most tools, you get what you pay for and cheaper units are likely to be less ergonomic or less well constructed. I have the following types:
1. OKI SHP-1060A
2. R.E.L HAP (Hot Air Pencil)
3. PACE Thermojet
4. Xytronic HAP80
My personal favourite is the OKI-1060A and I own three of them.
The hot air pencils do need a station to power them and provide air. The OKI and R.E.L. hand-pieces use dedicated stations. The PACE and Xytronic hand-pieces attach to standard de-soldering stations that also provide an air output. Most hot air pencils can be fitted with different diameter and shape tips to suit the task at hand. I use straight and bent tips in my OKI-1060A's.
The cheapest hand-piece is the Xytronic HAP80 at £28 +VAT from Rapid Electronics. You do need the 8800 desoldering station to power it though !
I have not tested the Xytronic HAP80 yet as it arrived today. I have no reason to believe it will not work as advertised however. the hot air tip design is not just a hollow tube. It has side air entry ports to increase the heat uptake of the air passing down the barrel and through it.
I am including some pictures of my hot air pencil hand-pieces and a pile of components that I removed from a scrap PCB with the OKI-1060A in just a few minutes. It is just so easy and controllable to use .
Fraser
First pictures are of the OKI hand-pieces....
-
Pace Hand-piece
-
R.E.L hand-piece
Note the very expensive air pathed LEMO plug !
-
Xytronic Hand-piece with detail of the non direct air path of the tip assembly to improve air heat take-up.
-
Handpiece size comparison.
I prefer the thinner pen type hand-pieces.
-
pictures of some SMT components removed easily from a PCB by the OKI hot air pencil. It can cope with some IC's and larger Tantalum capacitors etc.
-
Closer views of removed components. All of these were removed in a matter of a few minutes.
-
Hi Fraser, thanks as always for a detailed and insightful review.
Do you know if the SHP-1060A is actually available anywhere? Is it likely that one of these other hot-air pencils can be adapted to be compatible with it?
I notice that the Oki pencil also has a provision to operate with dry nitrogen instead of air. Have you tried that yet? -
Thanks for the posts; the only improvement would be if there had been a ruler in the pictures! I can understand why pencils might be ideal for ~0402 components.
My presumption is that in order to dump enough heat into the substrate, you need an appropriate combination of volume and temperature. For a given diameter nozzle that means lower temperature and higher velocity, vs lower velocity and higher temperature.
With desoldering, a high velocity can even be an advantage: you know the instant the component is desoldered because it is suddenly "somewhere else". But how does a pencil work with soldering, where blowing the component away is a very real probability and is somewhat unhelpful? -
Helius,
The OKI hand-piece is normally sold with the (now obsolete) SMT-1160 (model No. SMT1101-110V & SMT1102-230V).
I bought one set from the USA and the other two from UK sellers. The USA seems to have more of these for sale on ebay and they are quite rare here in the UK.The good news is that the heaters last a long time in the OKI handpiece so buying used ones is not such a risk. I paid less than £80 for my complete handpiece/station sets.
The OKI hand-piece heater is rated at 36Vac 80W so current draw is around 2.2A. The temperature sensor is, IIRC, a thermocouple.
All you need to drive it is a suitable power supply with thermocouple control loop, and a source of air.
Yes I noted the option to use a Nitrogen gas feed in place of air. I have not used such to date though.
Fraser -
tggzzz,
I have had no problems soldering 0402 components onto PCB's with the hot air pencils. You do have to hold the 0402 resistors and capacitors in place with tweezers but than I had to do that with a conventional hot air station as these components are so light and blow away easily.
it should be noted that the the hot air pencils are not weak sources of heat.... I actually melted down an SMT transistor with it once when I had the temperature set too high. The jet of hot air can be very hot indeed and you can set the air flow to high or low without fear of cooking the heater. If a large ground-plane is absorbing the heat, then yes I can imagine the hot air pencil may struggle, but I have yet to experience such an issue myself.
The hot air pencil can generate a very hot confined jet of air that is localised to just where it is needed rather than blowing over a large area that may then need protection. Another advantage of the OKI and R.E.L hand-pieces are their long thin heater barrels. They can get into parts of PCB's that larger barrels cannot.
I have seen people making hot air pencils by either modifying desoldering hand-pieces or making a hot air tip assembly for a conventional soldering iron. Performance is unlikely to be as good as a unit designed for the purpose but may be enough fr infrequent use.
Fraser -
I have had no problems soldering 0402 components onto PCB's with the hot air pencils. You do have to hold the 0402 resistors and capacitors in place with tweezers but than I had to do that with a conventional hot air station as these components are so light and blow away easily.
So far I've rarely had to use tweezers/forceps, but then I've had a volume of only 30 (range 20-100) with temperature ~320.
I'm occasionally tempted by the "nodding duck" shaped thingies that hold components in place with weight and gravity.QuoteI have seen people making hot air pencils by either modifying desoldering hand-pieces or making a hot air tip assembly for a conventional soldering iron. Performance is unlikely to be as good as a unit designed for the purpose but may be enough fr infrequent use.
I would certainly avoid that myself!
Thanks. -
Just had a quick look on ebay.com.
There is one SMT-1101 set with hand-piece for sale at $175 and open to offers. Another sold for less than $160 recently.
Maybe worth making an offer ?
http://www.ebay.com/itm/Metcal-SMT-1101-Hot-Air-Pencil-SHP-1060A-/122099450135?hash=item1c6db1c117:g:U5UAAOSwZVlXu00F
The stations are advertised under either SMT-1160 or SMT-1101 in the USA, but some do not include the hand-piece. They also appear under the OKI, OK Industries and Metcal names.
Fraser -
I did see that listing.
Thanks for checking the rating of the heater. My impression was that finding the connector would be difficult, but I didn't spend too much time looking. -
Helius,
Yes the connector appears to be unique to OKI and would need to be adapted for any other brand or DIY station. LEMO make connectors with a built in air/gas path but they cost a small fortune. The R.E.L station uses such a connector.
Fraser -
That hot air "pencil" from Pace is huge, looks like the same size as the Pace SX-100 solder extractor. I have a Pace TJ-85 "Thermojet" which is lot smaller and easier to use, however, the pump in the Pace ST-75 solder station is so loud it never gets used.
-
Closer views of removed components. All of these were removed in a matter of a few minutes.
Exactly.
It's very easy and repeatable, so much so that prototyping using SMD and hot air is really no problem with a little practice and thoughtful layout of the PCB to enable such.
I've got a standard sort of rework station with a quite large hot air pencil and with a 5mm tip. -
Just had a quick look on ebay.com.
There is one SMT-1101 set with hand-piece for sale at $175 and open to offers. Another sold for less than $160 recently.
Maybe worth making an offer ?
http://www.ebay.com/itm/Metcal-SMT-1101-Hot-Air-Pencil-SHP-1060A-/122099450135?hash=item1c6db1c117:g:U5UAAOSwZVlXu00F
The stations are advertised under either SMT-1160 or SMT-1101 in the USA, but some do not include the hand-piece. They also appear under the OKI, OK Industries and Metcal names.
Fraser
That smt-1101/1160, do they produce air for the use, or do they need and external source? -
They are self contained and use a quality integral piston pump to produce the pressurised air.
-
They are self contained and use a quality integral piston pump to produce the pressurised air.
Cool, need to look around a bit to find some with 220v powersupply. -
IIRC the OKI SMT1160 has 110V / 220V options on the transformer. I will need to check. The soldering stations certainly do.
The heater and pump run off the transformer output so no other supply voltage specific parts to worry about.
Fraser
-
Great thread
After reading this I have decided I need (want) one. I have a Xytronic 968. To which a HAP60 would fit but I can't find one. A HAP80 on the other hand is still available.
Information thin on the ground as to the suitability of the HAP80 and the suppliers I have already contacted are unwilling to confirm either way. Does anyone here know one way or the other?
Many thanks -
From memory, the operating voltage of the HAP 60 and HAP 80 is different.
I would need to check though.
Fraser -
Thanks Fraser.
I do believe you are right. HAP60 is 24v and HAP80 is 32v.
Could you tell me the I/D of the end of the HAP80 nozzle please? I'm trying to do a workaround.
https://www.eevblog.com/forum/beginners/dia60-as-a-hap/msg1667690/#msg1667690 -
From memory, the operating voltage of the HAP 60 and HAP 80 is different.
I would need to check though.
Fraser
That must also mean this page is wrong?
https://www.rapidonline.com/catalogue/search?Query=xytronic%20968&Disc=true