Surface mount v through-hole mount – what and why

PCB manufacture

Growing demand for smaller technology with increased functionality has led to considerable advances in the mounting of components onto printed circuit boards in recent years. There are two primary techniques for doing this, surface mounting and through-hole mounting (also referred to as thru-hole mount).  But which of these two is the most efficient and under what circumstances should either be used?

Thru-hole mounting

Thru-hole mounting is the older of the two methods and, until the 1980s, was the accepted manufacturing standard. It involves running component leads through holes drilled into the printed circuit board. Despite the expectation that thru-hole would be made obsolete by surface mount technology, the use of conventionally sized components requiring traditional thru-hole placement is still prevalent.

Due to their high reliability, thru-hole components are great for electronics which require better standards of connection between individual layers or the electronics in question need regular disconnecting and reconnecting. As thru-hole involves running a component’s leads through a number of holes drilled in the printed circuit board, products can take greater stresses than surface mounting would allow. It’s for this reason that thru-hole production is still required, particularly in the aerospace or military manufacturing sectors. Read our case studies here.

Surface mounting

Surface mounting is the newer of the two methods and was known as planar mounting when it was first developed in the 1960s – it grew to prominence in the 1980s. Surface mounting means mounting components straight onto the face of a printed circuit board, generally using solder. In modern manufacturing, almost all electronics are made using surface mount technology. It has been crucial to the design of modern printed circuit boards, improving their quality and performance as well as making production cheaper and much less complex.

There are three main advantages of surface mount over through-hole mount:

1. Fewer holes required in the circuit board

Surface-mounted components are affixed directly onto the surface of a printed circuit board and as such, do not require as many holes to be drilled (there is still a requirement as the connection has to be made to each side of the board, through ‘via holes’ but these can be planned in to maximise board space and layout). This reduction in drilled holes reduces production time and cost.

2. Create smaller components

With surface mount, both sides of the board can be used for mounting components, reducing the size of the board needed for the overall product and ultimately, reducing the product size. The advent of sensor technology with smaller and smaller components being used to create smaller and smaller sensor units is an example of this development.

3. Automated production processes

The advent of surface mount has meant that boards are designed for a standardised, automated process. This means that production volumes can be increased and the overall build times can be reduced, saving time, resources and costs.

FermionX Surface Mount and Thru-Mount Capabilities

Surface mount has resulted in manufacturers being able to produce densely packed, smaller and much higher performing circuit boards. There will always be specific situations in which thru-mounting is the more practical choice, but the advantages of surface mounting are clear; smaller devices, higher-performing printed circuit boards with a greater density of components (and potential functionality) with fast, cost effective production time.

FermionX have 2 Surface Mount lines chosen for a combination of speed and flexibility, enabling us to streamline workflow to suit product complexity and production schedules. A 3rd line is due to be added in August of this year. This flexibility allows us to produce prototypes through to higher volume manufacture, ensuring development and manufacturing time is reduced and route to market is smoother. From 0201 SMDs to micro BGAs we provide reliability in process and product.

Despite the continued miniaturisation of electronic components suitable for SMT placement, the use of conventionally sized components requiring traditional thru-hole placement is still prevalent. The quality of this thru-hole placement and soldering often sets manufacturers apart with emphasis on eliminating soldering defects such as blow holes, incomplete or cracked joints or even lifted components.

Our highly experienced conventional assembly team has an average of over 10 years’ experience in thru-hole assembly, so there is nothing they haven’t seen before. Our conventional assembly includes world-class hand soldering checked to IPC-A-610 and additional Wave Soldering functionality.

The team are exceptionally dedicated in their work and as well as ensuring solder joint quality, they also ensure the component assembly is tidy, with clean joints and level components. It’s a matter of professional pride!

Why not contact us to find out more about our build capabilities and how we can help with your manufacturing needs.


Posted in FermionX News.