While obviously factors like safety certifications and margins of error are more important when it comes to safety critical applications, e.g. aerospace, I saw an article that said that one of the remaining areas for through-hole components, is where reliability is important:

  • Through-Hole vs. Surface Mount: Through-hole components are best used for high-reliability products that require stronger connections between layers. Whereas SMT components are secured only by solder on the surface of the board, through-hole component leads run through the board, allowing the components to withstand more environmental stress. This is why through-hole technology is commonly used in military and aerospace products that may experience extreme accelerations, collisions, or high temperatures. Through-hole technology is also useful in test and prototyping applications that sometimes require manual adjustments and replacements.

But when googling through-hole vs surface mount reliability, a source painting a more mixed picture popped-up:

  • Through-Hole Vs. Surface Mount: Contrasting Benefits and Uses: Disadvantages: Since THT component leads are fed through the board, the PCBs must be pre-drilled, which is both expensive and time-consuming. It also restricts components to one side of the board and limits the available routing area on multilayer boards since the holes must be drilled through all the PCB’s layers. THT’s soldering process often makes the resulting solder points less reliable than SMT solder. Additionally, the THT assembly process is more involved and therefore more expensive than SMT.

Although this source isn't exactly neutral, being a mixed through-hole surface mount vendor. Is there a straight-forward winner when it comes to the reliability of surface mount vs through hole components?

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    \$\begingroup\$ The greater mass and longer leads of TH components can work against them in vibration testing. \$\endgroup\$
    – user16324
    Sep 6, 2022 at 16:51
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    \$\begingroup\$ The claim that through hole technology limits components to one side of the board is somewhat true, but also partially false. Soldering becomes problematic when components are on both sides of the board, but depending upon where components are intended to be placed, it is sometimes possible. \$\endgroup\$ Sep 6, 2022 at 18:40
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    \$\begingroup\$ @MathKeepsMeBusy I would say that two-sided SMT is practically taken for granted nowadays \$\endgroup\$ Sep 6, 2022 at 19:40
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    \$\begingroup\$ "Whereas SMT components are secured only by solder on the surface of the board, through-hole component leads run through the board, allowing the components to withstand more environmental stress" I find this to be an extremely dubious statement; I would love to see where the author derived that from. At the end of the day, components have so little mass that even at extremely high G-loads they exert almost no force on their connections and lead frames (F=ma) \$\endgroup\$ Sep 6, 2022 at 19:42
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    \$\begingroup\$ @Brendan Simpson - That is not true. Even relatively small parts can exert forces during vibration or shock can that can break them off the board, especially if the vibration input excites a mechanical resonance. Our analysis tools are so much better now than they were back when I first started, when the first time your found out you have a component attachment problem is after the first vibe or shock test when you opened up the assembly and found loose parts in the chassis. \$\endgroup\$
    – SteveSh
    Sep 7, 2022 at 0:13

1 Answer 1


While not a definitive answer, every recent (last 20 years) military and space product I've worked on has has been built using SMT (Surface Mount Technology). There were some exceptions for individual components, but that was more because the part was only available in the through-hole package, and not for any reliability advantage.

Sometimes, particularly for larger packages, we have applied an adhesive under the package or an epoxy to the corners. But that was only done when the structural analysis showed it was needed.

None of these applications were for what I would call extreme acceleration environments, such as a cannon-launched shell (a smart munition). But they do have to survive launch and stage separation pyrotechnical shock, and many thousands of temperature swings.

Finally, many components are just not available in through hole packages. For example, show me a 1000+ pin FPGA in a through hole package. In those cases ways are found to make them work in the given environment.

Leaded parts are always preferred where large number of temp excursions are involved. The largest leaded part I used was an Actel (now Micro Semi) FPGA in either the 256 lead or 352 pin Ceramic Quad Flat Pack (CQFP) package, I forget which (was over 15 years ago). Even though it was SMT, because of the fine lead pitch, it could not be solder automatically and required a trained operator to hand solder it down.

Everything (COTS) I've seem above that IO count has been been in some sort of BGA or CGA package, which requires careful attention to board material (so as to minimize CTE mismatch between the package and the board) and staking and/or underfill of the package to the board.

You can get high IO count leaded packages, but they are usually custom designed and built MCMs (Multi Chip Modules).

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    \$\begingroup\$ Yes, almost everything for space and military is SMT now. Large leadless parts are a challenge because of thermal stress on the solder joints. So, generally, leaded SMT parts are used whenever possible. \$\endgroup\$
    – Mattman944
    Sep 6, 2022 at 16:15
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    \$\begingroup\$ One exception is controls and external connectors, the sort of things that get bumped accidentally, SMT parts tend to peel the traces off the PCB. though hole parts are more robust, combination TH and SM parts also seem fine. another is the input filter capacitor on the early Raspberry Pi. it was perfecly placed for thumb leverage when unplugging the power. \$\endgroup\$ Sep 7, 2022 at 13:02
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    \$\begingroup\$ @Jasen - Agree about the external connectors. While most internal-to-the-box connector are surface mount, external connectors mounted to a PCB, which tend to be Mil-38999 circular, are through hole mount. \$\endgroup\$
    – SteveSh
    Sep 7, 2022 at 13:42
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    \$\begingroup\$ The first time I ever saw surface-mount packages was on a tour of a NASA facility -- in the mid-1970s. SMT has been preferred for aerospace applications for a very, very long time, I think. They reduce mass and volume, a critical goal for something that has to be launched. \$\endgroup\$
    – jeffB
    Sep 7, 2022 at 17:46

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