Demise of the Plated-Through Hole?

Demise of the Plated-Through Hole?
How long will the industry continue to use through hole components? I can envision connectors being used for some time, what about component types? Phil Zarrow and Jim Hall, The Assembly Brothers, discuss this question.
Board Talk
Board Talk is presented by Phil Zarrow and Jim Hall of ITM Consulting.
Process Troubleshooting, Failure Analysis, Process Audits, Process Set-up
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Phil Zarrow
Phil Zarrow
With over 35 years experience in PCB assembly, Phil is one of the leading experts in SMT process failure analysis. He has vast experience in SMT equipment, materials and processes.
Jim Hall
Jim Hall
A Lean Six-Sigma Master Blackbelt, Jim has a wealth of knowledge in soldering, thermal technology, equipment and process basics. He is a pioneer in the science of reflow.


Welcome to Board Talk with the Assembly Brothers, Phil Zarrow and Jim Hall, who by day go as ITM consulting, but are here today high atop Mount Rialto in the recording studios of Board Talk to answer your questions.

This question is about through hole components. "How long do you expect the industry will continue to use through hole components? I can envision connectors being used for some time, but what about the other component types?" This comes from J.C.

It's the end of the via as we know it.

If they go away do we have to play TAPS at the end? We've got a bugle right here on the wall.

I remember the early days of surface mount there were some people who declared, "Ah, surface mount is just a fad".  Of course, they're not around anymore.

I remember in the height of the surface mount revolution people were saying through hole components are going to be gone. I worked for a company that made insertion equipment and they were ready to pack it up. They ended up building a small modular unit. They thought it was going to have a two to three year life yet they couldn't make them fast enough. They were making them till the end when they were acquired. 

And those guys are still building. Well, the one you worked for no longer exists but the one I worked for is still building pin insertion equipment.

I don't know about wire wrap but I can also recall another story. This goes back about '82, '83, I remember talking to a designer at Apple Computer and they were building the Apple 3C, if I recall this was pre-MAC. He said, "Not only do I foresee using a D type connector for the joystick, but I'm looking at one military grade."

I said, "How come?" He said, "Because it's got to withstand the force of a 10 year old kid plugging the thing in and pulling it out." So that's the driver for through hole components, typically, is the service life that they're seeing. 

I think JC refers to that with his comment, or her comment, on connectors.  But I want to bring up another thing and that is that we still have dip packages around. Why? A lot of it's just inertia. Companies that are building them, they make a profit, they got all the equipment, it's paid for - they're not going to stop until something breaks or somebody absolutely refuses to use it. 

You don't think it's a conspiracy from the guys who built dip inserters, do you? Inquiring minds want to know. 

The other thing is parts that are not surface mountable, such as electrolytic capacitors. They can't withstand re-flow temperatures, you make them in a through hole package and hand solder them.

But again, you go off and get into the mechanical issue, whether they feel that the through hole joint is needed for mechanical strength as in connectors.  So, I don't know, I don't have a crystal ball. As long as you're going to have connectors, as long as you're going to be wave or selected soldering, I don't know how much it matters. 

By the way, do you know where I can get a good vacuum tube these days?  Well, that's our philosophy for the day, the answer is through holes use is going to be around for the foreseeable future. They'll be around longer than we are. Beyond that, thank you for turning into Board Talk.

Don't solder like my brother.

Don't solder like my brother.


You jest but tubes are still with us as well. You will not get 1 million watts of continuous wave illumination for a fire control radar out of SMT components. Also what about all those magnetrons in microwave ovens?
Frank Honyotski, STI Electronics Inc.
Focus on reducing annular. Do an not worry about PTH/PTV existence. Improve materials and processes to achieve predictable registration. Don't waste time otherwise.
Jerry Magera, Motorola Solutions
Parts which require mechanical mounting integrity, connectors as noted but also high-mass magnetics (inductors, coils, transformers, relays) need to be through-hole. Nearly all of the boards I've worked on (medical electronics) are mixed-technology boards. Certain other high-power components (amplifiers, etc.) benefit from TH mounting and mechanically mounting heat sinks (often TH mounting tabs) are also typical. Unless/until someone changes basic physics, I don't see through-hole components going away.
Alan Ritter,, LLC
Hey, Assembly Brothers! Are things so bad that you're recycling old questions? Wasn't this the exact same question asked when I started in this industry, 38 years ago? LOL!!! Yeah, this question comes up every year, and likely will for the entire career of a person entering the industry today. Of course, there has been one other constant in my 38 years ... I've been wrong before. I miss you gentlemen. Thanks for all you both do for us.
Rick Short, Indium Corporation
Populating TH components into the PCB is a manual process. Although we are at 98-99% yield, when we miss, it puts us in a bad situation with the customer. I wish industry could come with standards to make TH components, so that it could go into the PCB in ONLY one way. (mistake proof - maybe make one lead thicker that the other, zig zag hole pattern).
Sundaram Kumaravelu, EIT LLC
In my industry, we qualify our components for EXTREME environments and that qualification can take 20 years+. Because of this, we use Through Hole components extensively as they are far more reliable.
Anthony Upton, Schlumberger UK
I agree with Jim and Phil and most of the others based on their own experiences. The THROUGH HOLE will stay at least for another decade - since world over takes time to change older techniques and methods do not die or become extinct in a flash.
Ranganath M A, TQM Consultancy
Thru hole connectors - I have been designing board level electronics since 1974 - 10 year old designing a DMM, nearly a lifetime ago. Thru hole plated - > 16 times the strength of SMT. So for connectors it is sensible. Brute force, ignorance and a lack of understanding on the customer side is to be presumed. Why do PC motherboards still use thru hole connectors, PCIe, DIMM and IO? Dual sided SMT and thru hole connectors - it works even although the expense of additional manufacturing steps. The operating profit margins if you make millions of devices are slim - say 4% - warranty returns decimate a profit margin. I do and always have designed in the industrial and medical markets.
D. Greig
As one who fiddles with circuitry for fun at home as well as for money at work, I certainly hope that TH never goes away, at least until I do. These 64-year-old eyes do NOT work and play well with any but the largest SMT!
Michael Moran, Digalog Systems Inc.
My company manufactures both Through-Hole and SMT connectors and other components. We do not see any drop-off in demand for Through-Hole products - and we are still introducing brand new connectors in both formats, and both are selling. Not exactly an industry trend, but we're not seeing any sort of end!
Wendy Jane Preston, Harwin plc
A point of order, "plated through holes" are not for through hole component they are for conducting from one side to the other. Comming from a punched world of low cost analogue products, a 'hole' is for through hole components. I did find it odd when digital based customers refer to PTH while pointing at a single sided board. Holes do not have to be plated for through hole components, it is more secure but that is partly what the leg shoulder is for. As long as parts are fully inserted (usually clinching secures this, either manually or automatically) and soldered on the other side, with a suitably sized hole, the solder will not break under stress.
Tony Stanley, Tyco Security Products
Not only component connections but even vias will be produced as plated hole. Trough hole vias are much less expensive than buried or blind vias because less procedures are required to produce a board. So long as low priced boards are desired you will find that holes will be produced with lowest production costs in mind.
Daniel Schoeni, ETH, Switzerland
Connectors and lytics can be and are being produced as surface mount components. I'm looking at a PCB right now and the only things that aren't surface mount are the connectors and one power inductor, all of which could easily be converted to surface mount. I think that reliability is the primary concern keeping these parts through hole but as long as there's some type of auxiliary mechanical attachment to the board to reinforce the surface mount I think the parts should be fine. The connectors that I mentioned already have screws in un-plated holes and the choke has an adhesive pad to add mechanical strength.
Almoore, Harman, USA
In the Medical Industry, in terms of reliability, in most cases through-hole technology is far superior to SMT. I hope that it has a long life.
Glayson Figueiredo, Philips Medical Systems, Brazil
I have to agree with Chip Entringer of Dean Technology (a competitor of ours). There are just some things you can't do with SMT that you can with PTH. Most notably high current power conversion and high voltage up to and beyond 180kV. If you take away the PTH components many products will be impossible to make with the existing SMT technology. We don't deal in microamps. We deal in amps, kilowatts and high kV.

SMT is great for control boards (that is what we mostly use), cell phones, MP3 players and tablets (note I didn't mention all the iProducts). PTH gives us the flexibility to build one or two prototypes with incurring the cost of stencils and placement machine setups without spending a small fortune. PTH lends itself to low volume, high mix. SMT really wants to be low mix and high volume.
Phil Nutting, Excelitas Technologies, Corp., USA
I am eagerly awaiting the arrival of this along with the paperless office and toilet.
Charles Stringer, Edwards Vacuum
The use of components with higher physical load like bigger dimensions, exposure to mechanical stress or higher weights leads to a need of reliable fixation. A combination of electrical contact and mechanical fixation in a PTH is more efficient than a combination of a SMD footprint and a TH for additional fixation if possible. However it depends from the application and the environment.

There are still some older components (older does not mean died off) like tubes, rotary capacitors and more and these will still be used as PTH components. Even shielding is becoming more important as there are components with shielding pins that are mounted in PTH (pressed, not soldered). Maybe some kind of wired resistors and capacitors will decrease but in my opinion PTH components do have its own entitlement and will never die.
Daniel Schoeni, ETH Zurich
I think this is a VERY misleading question. Reminds me of some of the outstanding political surveys this wonderful election year - at least in the USA.

This presumes that plated thru holes (PTH) are only used for component mounting. VERY FAR OFF BASE. My guess is that only a tiny fraction of PTH are used for component mounting. Some components,like power supplies, relays, and other heavy components must be through hole mounted for reliable performance in harsh physical environments -vibration,drop shock,etc. I refer you to the NASA/DoD studies of Pb based versus Pb-free solders. Those confirmed the "bullet proof" nature of through hole mounted pDIPs compared to SOICs.

Next, PTH is widely used as simply electrical interconnection between surface layers and to inner layers, also.

Then, PTH is used as electrical connection in many sub-assemblies, laminated into multilayer boards. These become buried vias.

Finally, the use of "via farms" is growing rapidly, as the power dissipation in complex ICs runs into the 10s and even 100 watts. I was recently amazed at the via-farms for heat removal in an automotive engine controller. Not just to the inner layers and the opposite side of the board, but even using conductive grease, to the metallic shell of the engine control box. What next - a radiator hose to the electronic brain of the car?
Dennis Fritz, SAIC,Inc
The Demise of the Plated-Through Hole? Hardly. As long as there is a need to interconnect circuit layers within a PCB there will be plated-through holes (PTHs). PTHs have in-fact proliferated in quantity and form, including blind, buried, filled and build-up technologies. But for Component PTHs, the Guys got-it right.
Robert Lazzara, Circuit Connect, Inc.
TH parts will be around as long as circuit board assemblies continue to be used. Regardless, plated through holes will always be needed for the via holes. I'm really surprised you guys didn't mention that in your Board Talk program. After all the title of the article is "The Demise Of The Plated-Through Hole" and not the Demise of Through-Hole parts.
Jerry Wetzel, Innovative Imagineering
You mentioned electrolytic capacitors and connectors. As a manufacturer of high voltage power supplies, I will also add to the non-SMT list heavy components like transformers that are likely to tear off the copper clad if surface mounted. Also high voltage components (>3000V) that cannot be located close to each other and therefore do not need to be SMT. Finally, there are some power devices that actually take up more board area in their SMT version than the thru-hole versions (TO220, etc.).
Chip Entringer, Dean Technology

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