Most hardware teams sweat over BOM, which makes sense, as the Bill of Materials is the blueprint that lists every part, every screw, and even every chip. It tells you exactly what goes into your product, and is the holy grail of hardware design. 

This is the reason why, during any failure, people jump to the conclusion that there must be something wrong with their Bill of Materials. But here’s the thing no one tells you until it’s too late: The BOM is only 80% of the build story. The remaining 20%? Even with a flawless BOM, your product can still fall flat on its face. In this article, we are here to discuss the missing links between your parts list and your final product assembly. 

So, without further ado, let’s talk about what happens beyond BOM, and what if Box Built Assembly needs a little more attention than it gets? 

What Is BOM?

So, firstly, what is Bill of Materials? If we put it simply, it is a list of hardware parts that you need to build your device. This includes:

• Microcontrollers
• Screws
• Sensors
• PCBs
• Casings
• Connectors, etc.

Basically, it tells your sourcing team what to buy, your finance team knows what it costs, and your factors know what to expect, because of this list called BOM.

And because it is so foundational, teams rely on it a lot. Which one should, as a bad Bill of Materials, mean there can be wrong parts, expensive delays, and a product you cannot ship.

That doesn’t mean a good BOM guarantees a good product. So, what to look out for? Box Build Assembly!

What Is Box Build Assembly?

That Box Build Assembly is the crucial step where everything comes together, like:

• Mounting your PCB into the enclosure
• Routing wires and cables neatly
• Connecting displays, buttons, and sensors
• Applying the right torque on fasteners
• Labelling, testing, and packaging

So, if someone asks you, “What is box build assembly?”, the simplest answer is that it turns all the parts into a finished, working product that is ready to be shipped. But, this is where most teams do not plan properly, as they assume parts are right, and so the assembly should just work. 

Spoiler: It doesn’t!

BOM vs Box Build

Aspect	BOM (Bill of Materials)	Box Build Assembly
What it is	Parts list	Actual build process
Purpose	Tells you what to source	Tells you how it fits together
Ownership	Design, Sourcing teams	Manufacturing, QA, Ops
Common Issues	Missing parts, wrong specs	Cable strain, tool access, and misalignment
Trackability	Spreadsheet-friendly	Often undocumented
False Assumption	“If BOM is right, we’re good.”	“Assembly is just plug-and-play.”

BOM Is Rarely the Real Risk

Have you ever been in a situation where:

• The parts in hand
• The PCB is tested
• The enclosure looks slick

You run your first batch, and suddenly:

• The cables don’t fit the way you thought
• The light pipe doesn’t align with the LED
• The enclosure doesn’t close because the connector is too tall

Well, that is the gap that usually lives in the zone your BOM spreadsheets cannot track. This is where box build assembly challenges start hitting. And trust us, they can be pretty hard to keep an eye on. Because now, instead of fixing a spreadsheet, you are reworking the physical hardware. This can cost you a lot of time and money.

Real-World Box Build Assembly Challenges (by Product Type)

Now, let’s look into how Box Build Assembly can create challenges in otherwise great builds:

• EV Battery Packs:

While BOM covers cell machine matching and connector specs, the real issues often happen in the building part of it. There can be thermal interface failures, casing misalignment, or inconsistent torque application.

• Consumer IoT

Another one is that your BOM might have the right antenna and MCU. But when it comes to assembly, there can be other problems like enclosure clipping, LED light pipe diffusion, or cable routing that become the bottlenecks. 

• Industrial Systems

Yes, the relay specs and PSU ratings are locked in the BOM. But on the shop floor, you have to deal with rack mounting fitment issues, wire harness strain, and grounding loops, which can lead to failure!

• Medical Devices

If you think you have sourced all the right sensors and compliance parts, so you are in the safe. No! You also need to keep an eye on sterile handling, labeling precision, and specific tool access, which can also delay production at the final product assembly stage. 

So, one thing is clear: these are not sourcing problems, but instead, these are box-build assembly challenges, for which a partner like Karkhana.io can help!

 

Why This Problem Keeps Happening

Now we have the answers to the “WHAT is happening”, but what about “WHY is it happening?” When we talk about Box Build Assembly causing problems, we cannot ignore why it is happening in the first place! So, below are the reasons why this problem keeps happening:

• Design vs Floor Disconnect

You designed it in CAD. It looked perfect. But the technician on the floor? They’re twisting tools in tight spaces, trying to route a cable that looked simple on screen but just doesn’t bend that way in real life. This is the clear disconnect between design and floor, which made sense in theory, but in practice, it becomes impossible! 

• No One Owns Final Assembly

The process goes smoothly: Mechanical checks off their parts. The electrician signs off on their wiring. Firmware runs its tests. But the moment it comes to putting the whole thing together, like routing the wires, fastening the casing, labeling, and sealing, the problem happens. No one in the team is fully responsible for the entire final product assembly. 

• Bad manufacturers stick to the Script.

Even if everything goes well, a manufacturer who is just going by the script can create the problem, too. They follow what’s in the drawings and what’s in the files. But box build assembly isn’t always black and white—it needs judgment, which needs experience, and a smart manufacturing team who can think:

• How much force is too much when seating a connector?
• Should you connect this cable before that one?
• Will the tool needed for fastening actually fit in this gap?

These small decisions can affect yield, reliability, and speed. And if you haven’t shown them how to do it, your EMS partner will calculate!

How to Fix It: 3 Things Great Hardware Teams Do

Now, here is where the best hardware teams get it right and fix the problem with Box Build Assembly:

• Run Assembly-Level DFX Reviews

They go beyond Design for Manufacturing (DFM). Run Design for Assembly (DFA) reviews that cover:

• Interconnect paths
• Cable strain angles
• Operator access points
• Fastening and torque tolerances
• Labeling and orientation consistency

• Build a Golden Sample + Record It.

Did you know that viewers retain 95% of information from videos, compared to only 10% when reading text? So yes, next time, do not just send drawings, but build one perfect unit, and record a step-by-step video of the box build assembly process.

• Simulate Packaging and Handling

Did you think you were done once the product was assembled? No! You also need to:

• Simulate drop tests
• Stress test packaging
• Watch how it’s unboxed

Final Thoughts: Why Karkhana.io?

Now you have all the answers to “What is bill of material” and “What is box build assembly.” If there is one takeaway from this article, it should be that shipping hardware is not just about what’s on paper, but also about how it actually works, reliably, once it’s out of your office. So yes, you can obsess over your BOM, but if you are not thinking about box build assembly from day one, you’re leaving your product’s success to chance. 

This is why, at Karkhana.io, we focus on the part of the hardware journey most teams overlook: box build assembly. We think beyond BOM and bring structure and clarity to a phase that is often left to chance.