The document describes through-hole (THT) and surface mount technology (SMT) in PCB assembly, highlighting their differences, advantages, and disadvantages. THT involves manually inserting components with long pins into pre-drilled holes, making it suitable for larger, high-reliability products, while SMT is automated and allows for denser configurations. Despite THT's longer production time and higher costs, it remains relevant due to its strong mechanical bonds for specific applications, such as military and aerospace industries.

1. Through Hole PCB Assembly
THT PCB Assembly Manufacturer — One-stop service
What’s mean for Through Hole (THT) PCB Assembly
and Surface Mount Technology
（SMT）
PCB Assembly ?
Surface Mount Technology (SMT) is necessary for PCB
assembly. If the PCB has no through-hole
components, Through Hole (THT) PCB Assembly is not
needed.
SMT assembly: SMT stands for surface mount technology,
which is a versatile PCB assembly technology. Currently, all
electronic components can be made into surface-mounted
devices (SMD). SMDs are interconnected to the PCB pads with
solder paste. SMT assembly is automatic.
THT assembly: THT, or PTH or DIP, means through-hole
technology. The electronic components that require THT
assembly have long pins. Usually, they are capacitors, fuses,
and connectors. The PCB is pre-drilled, and these components’

2. pins plug in the holes and wave reflowed. THT assembly is
manual.
In the PCB assembly process, SMT assembly happens before
the THT assembly.
What are the benefits of Through Hole PCB assembly?
Through-Hole PCB Assembly comes with a range of benefits
including:
Withstanding stress-As opposed to SMT components,
through-hole components are known for their ability to
withstand mechanical and environmental stress.

3. Perfect for large components-Through-hole works well for
large components that have to undergo high power and high
voltage
High heat tolerance-Known for their high heat tolerance, they
find application in a number of industries, particularly military
and aerospace.
Ease of Prototyping- Through-hole PCBs also lend themselves
to ease of prototyping and improved reliability
High Reliability-Through-hole PCBs are best used for
high-reliability products that require stronger connections
between layers.
Little surprise then, that even though surface mount
components allow for denser configurations, for larger and
heavier components that require strong bonds, through-hole
technology has remained resilient and relevant.
What are the capabilities you offer for Through Hole
PCB assembly?

4. We provide through-hole PCB services to a variety of industries
including medical, electronics, instrumentation, and military,
all thanks to our complete assembly capabilities:
• Hand soldering
• Dual wave flow solder
• Hand Insertion of components
• Automate axial or radial insertion
• RoHS soldering using tin-lead solder
• Use of high and low melting point solder
• Prototype build to high-volume assembly
• Functional test and automated inspection
 Support various types of PCBs including metal core PCBs,
Rigid PCBs, Flex-rigid PCBs, FR4 PCBs, etc.

5. Disadvantages of Through Hole Assembly
Like any other manufacturing or assembling techniques,
Through Hole PCB Assembly has its disadvantages too.
These include:
Longer production time-It takes a lot of time to drill the
multiple holes through which the leads are expected to run.
Expensive-because the drilling process is difficult and
time-consuming, it increases the cost of production

6. Minimizes space on the boards-drilling the holes on the surface
of the board limits the routing area for tracing signals.
Also, by feeding the leads through the board, only one of its
sides is usable, thus making the THT PCB a bit slower in
operation speeds.
Through Hole Assembly Components — What are the Best
Components for Through Hole Assembly?
Radial lead components
Axial lead components.
Types of Through Hole PCB Assembly
There are two (2) main types of the Through Hole PCB
Assembly. The first is the Automated Through Hole PCB
Assembly. The second is the Manual Through Hole PCB
Assembly.
On the one hand, the automated variant is roundly touted to be
faster and cost-effective because it takes little time to be

7. completed. It also demands little human inputs, which makes it
cost-effective.
On the other hand, the manual Through Hole PCB Assembly
involves the traditional or manually-operational model of
drilling the holes into the Printed Circuit Boards (PCBs). This
model tends to take time and attracts more costs.
Functional tests and automated inspection for
Through Hole PCB Assembly
Using automated inspection is very critical in minimizing
turnaround time to ensure timely delivery of the boards.
Conclusion
As you can see, Through Hole Assembly of PCB can be time
consuming.
However, in some applications, it is worth it more so when
mounting heavier and bulkier components.
You can easily achieve the strength by soldering the
components on the reverse side as you have seen.

8. In fact, it is virtually impossible to pull components assembled
using Through Hole Assembly.
The good news, today’s guide has simplified the Through Hole
PCB Assembly technique.
Do you have questions or inquiries on Through Hole
Assembly process?
Contact us now. sales@hitechpcb.com

9. In addition to through hole PCB assembly, we also provide
value-added services, such as conformal coating, labeling, and
complete PCB encapsulation.
Through-hole PCB Assembly Testing and Inspection
at Hitechpcba
In-Circuit Testing:
This type of testing is conducted for high volume production
lines, and helps us check every minute soldering and other
components in detail.
Automated Optical Inspection: Abbreviated as AOI, these tests
are performed to ensure that product is free from soldering,
component, and BGA defects.
Automated X-Ray Inspection(AXI):
This testing is performed to inspect insufficient fills, short
circuits, fills, etc. The automated X-ray inspection helps reduce
the number of defects and improve the quality of the
Through-Hole circuit.

10. Burn-in Tests:
These tests detect components’ failure or reliability in real
environments.
Assisted Visual Inspection:
Our experts use a wide range of advanced visual inspection
equipment to perform a detailed inspection of soldering and
component placement accuracy.

11. What’s difference between SMT assembly and THT
assembly?
Most contract PCB Assembly manufacturers concentrate on
their surface mount technology capabilities for PCB assembly.
The SMT lines can be almost completely automated making it
possible to run a high volume of boards with little human
intervention and a low cost per board. Through whole assembly
whether automated or manual is a slower process, it takes

12. resources away from the high-volume business that many
manufacturers prefer.
Only about 10 percent of the parts we buy are through-hole.
Nearly 75 percent of the boards we run are mixed technology,
which is a combination of through-hole and SMT parts one
reason for this is that nearly half of our board assemblies are
for high powered boards which use capacitors inductors and
transformers to transfer energy. The size of these components
is proportional to the energy they can store so for a high-power
board we need to use some fairly large and heavy components
and that means through-hole technology, in addition things
like customer accessible connectors, that have to withstand
stress as cables are connected and removed are likely to be
through-hole components. Through-hole components are held
in place by the pins as well as the solder so you can get a much
stronger and more reliable mechanical bond than with surface
mount components that have only solder to hold them in place.
If a contract manufacturer is focused on higher volume SMT
business, it’s important to understand how they will handle
through-hole components when you need them at z-axis. We
run mixed technology boards every day we have a modern stuff

13. line with a paperless process for assembly instructions and
assemble in a single piece flow from the stuff line to a wave
solder to inline inspection, d-paneling, qc testing.
In addition to PCB Assembly, be it through hole or surface
mount, at Hitech Circuits Co., Limited we also undertake PCB
assembly rework offering complete reliability, high quality and
optimal costs. Not only are we well-versed in inventory
management, fabrication and process control, we also have a
stringent control on vendor component management.