If you need a PCB board for your product,
you're at the root of a basic problem with PCB fabrication and assembly. The
reason is simple: many manufacturers claim both fabrication and assembly, but
they often lack one. So this decision is very important to launch your product
on time.
What
Is PCB Fabrication and Assembly?
PCB fabrication is the process
of manufacturing the board. Technicians convert your design into layers of
copper, insulation material, and traces. Next, it's time for assembly.
Thousands of tiny components are placed on that board, soldered in place permanently,
and tested to ensure that they function.
Now this is the real world.
Most manufacturers design their products for either fabrication or assembly.
You have to deal with one company; they generally outsource the PCB assembly to
a partner, and you have to wait. Simultaneously, communication is also lost. A
one-stop PCB manufacturer performs both tasks in a single location.
Why
Many Buyers Prefer One-Stop PCB Fabrication and Assembly
For example, if you have to
share the work between two suppliers, it can be a real headache. For example,
PCB fabrication companies will manufacture your board per your specifications.
However, they won't know how assembly affects design.
If you use one manufacturer for
both services, their engineers review your design before fabrication starts.
They ask questions. They can recognize issues that generally cost money to
correct later. This is called DFM.
You may have a shorter timeline
as a result. Your costs drop. Your quality improves. Why? Communication is
short distance. One project manager is responsible for tracking everything. A
quality team is observing all actions.
What Actually Occurs Inside PCB Fabrication and
Assembly
Design Review
Your design begins with files.
These files are uploaded to the manufacturer's software. Technicians do what
they call artwork. This is an image, much like a blueprint, that directs all
the machines in this artwork.
Board Fabrication
Here is the process for the
fabrication part. Photolithography is the process used to create Copper layers.
Basically, the manufacturer shines light through a mask to form patterns on the
copper. Unwanted copper is removed by chemical processes. Multiple layers stack
and bond together. The holes are then drilled to attach parts. This is no easy
task. One mistake will ruin everything.
Assembly
When the board is finished, it
goes to assembly. The components are delivered in reels or trays. A pick and
place machine reads your design file and places each individual component. The
purpose of this machine is to be fast and accurate. The challenge, however, is
that it will not operate without complete data.
Soldering
Then comes soldering. In this
type, the board is moved through an oven. Next, the solder paste, along with
heat, will fuse the parts to the board. Averaged temperatures are not
acceptable. If it is too hot, components will be damaged. Solder joints fail if
they are too cold. The point of manufacturers investing in an expensive oven is
to see if your board really works.
Major Problems That Damage Product Quality
Let me list what actually goes
wrong in fabrication and assembly, based on experience.
Defects in PCB
Fabrication
Rather than design flaws,
fabrication defects occur when machinery is no longer operating within
established tolerances. Consider that one company specifies a trace width of
0.2 millimeters. The fabrication machinery, when properly calibrated, should
produce traces of exactly that width.
However, if the machinery
produces traces that are 0.18 millimeters wide, there is a fabrication defect,
and the circuitry will not function as intended.
Defects in Solder Paste
Printing
Surprisingly, the process of
Solder Paste Printing is critical to the function of the circuitry being
produced. This is because there must be exactly the right amount of Solder
Paste on each pad. If there is too much solder, a solder bridge is created, and
a short circuit occurs. Conversely, if there is too little solder, the joint
can become mechanically faulty and fail. This is also one of the most common
causes for failure in PCB assembly.
Component Placement
Issues
A common defect in PCB assembly
is incorrect component placement. This can occur with very small components,
such as the 0402 Capacitor, which can be placed upside down. An incorrect
placement can even occur for a 180-degree rotation of a component. This can
occur when a technician reads a mislabeled resistor label and places an
incorrect resistor into the machine.
The multiplication of errors is
the actual problem. For example, if you have a PCB with 500 components and the
placement mechanism has a 99 percent correct placement rate, there will still
be 5 components incorrectly placed, and the board will not function as
required.
Reflow Soldering
Reflow soldering can also
result in defects, such as cold joints, which occur when the solder does not
melt completely, and a component does not sit flush with the PCB. A connection
is fully functional; however, over time, if the board is subjected to vibration,
it will fail. Bridges between solder, which connect two or more components that
should not be connected, will also form.
Risks of Supply Chain
Sourcing
Risks associated with supply
chain sourcing are becoming increasingly more critical. The reason for this is
counterfeit components. A seller might say they possess authentic chips, but
the truth is they are from reclaimed or previously used inventory. Typically,
these components fail soon. Certainly, this is a serious threat that many
buyers neglect until failures occur in the field.
Lack of Inspection and
Traceability
Lack of inspection and
traceability prevents substantiation of why problems occurred. The manufacturer
has assembled your board, but they lack documentation on the specific reflow
oven used to process your batch, the technician who loaded the components, and
the test results. When a customer calls with a failure, there is no data to
investigate.
What
to Check Before Choosing a PCB Fabrication and Assembly Manufacturer
Before ordering, see PCBA
manufacturing facility. In fact, this is more significant than reading their
web page. These are the things to keep an eye out for.
Equipment
Ask them what equipment they
have: Do they have automatic optical inspection, called AOI? This machine takes
images of all the boards and compares them to the design, identifying placement
and soldering errors that are not visible to the human eye. Do they have X-ray
equipment?
Check Process
Documentation
Secondly, inquire about their
process documentation. Ask them to draw a picture of how they work. Questions:
Who types who?Questions: Who checks who at each step? For instance, do they
test bare PCBs after they're made, before PCB assembly begins? Without
performing this, defects propagate. Are components checked prior to
installation? Is there any pre-ship testing done of finished boards?
Component Sourcing
Thirdly, inquire about their
suppliers. Where do they get their parts? Are they in direct or indirect
contact with manufacturers? Are they able to present documentation of the
authenticity of components? Why it is important is that one batch of bad components
can spoil hundreds of boards.
Traceability System
Fourth, learn about their
traceability system. Are they using Manufacturing Execution System (MES)? This
software logs all boards and the machine that processed the board, and stores
test data. So, if you call in about a problem, they can pull up what happened.
Rework Capability
Fifth, check their rework
ability. Mistakes happen. If they do, can they fix the board, or do they have
to throw it away? With the right equipment and adept technicians, boards can be
salvaged and put to good use where they might otherwise be discarded.
How
PCBasic Supports PCB Fabrication and Assembly Projects
PCBasic is one of the top
one-stop PCB manufacturers that does several things that most don't.
All-in-one PCB
Fabrication & Assembly Service
PCBasic brings everything
together in one place. They handle board fabrication, parts ordering, SMT
assembly, and box assembly. Their website will provide you with a fast PCB
online quote. This tool provides you with prices quickly, without waiting for an
email. The online quote system connects to major component sellers via the API
to give real market prices.
Prototype and
Small-batch Production Support
PCBasic offers PCB
prototype and small batch services without any minimums. So why is this
important? Your design has to be tested before you make a thousand of them! If
a manufacturer asks you to purchase 5,000 boards to test, you are wasting
money. The better way is to make 50 boards, test them, identify the issues, and
then proceed to volume production.
DFM Review
You can have the DFM reviewed
before paying anything with PCBasic. This is the role of an engineer: to
consider your design and advise you on what will cause issues. For example, if
you have parts in your design that are too close together, the pick and place
machine won't be able to reach them. Your traces will be weak if they're too
fine. These are solved before the fabrication process – saving money and time.
Component Sourcing
Support
PCBasic is the software for
managing component sourcing. As a result, they don't let you go around
searching for hard-to-find parts; they find them for you. For instance, if a
specific chip is back ordered all over, they will order it from their network or
another similar component.
AOI & X-ray
Inspection
PCBasic has AOI and X-ray
inspection. These machines detect the defects automatically. This is important
because manual inspection is not possible. A fatigued technician overlooks
issues. They are all secure each time a machine catches them.
Functional Testing
Support
Functional testing is performed
using PCBasic. An unstressed board will look great, but will not function
electrically. Functional testing actually powers up your board, runs through
all its circuits, and tests its functionality. Testing methods vary among
boards. An understanding PCB fabrication and assembly company will collaborate
with you to develop suitable test procedures.
Traceability and
Quality Control at MES.
With MES systems, PCBasic
follows everything. To keep you updated on your order. Test reports are
available for download. If something goes wrong, and you have evidence to show
it.
Conclusion
With turnkey PCB assembly
manufacturer, you can avoid bad parts and late delivery in your electronic
project. You will hear promises from everyone, without doubt! The question is
which of these can truly demonstrate the proof? Request their AOI reports, test
results on sample boards, and documentation.
Price is important, but the
lowest price can be an indication of lower quality. So assess on the basis of
overall cost. The added expense of a good manufacturer's product is not as
significant as the rework and failures of a cheap supplier.
FAQ
What files do you need for a turnkey PCB
assembly price?
The Gerber file and an accurate
Excel part list must be submitted. Manufacturer code numbers and part
coordinates will be added.
How does PCBasic avoid fake parts?
PCBasic sources its parts
directly from original factories and authorized global suppliers. They maintain
proper records so they don't end up with unverified brokers.
Can you assemble boards with complex
chips?
Yes, the SMT machines are
equipped with high-resolution cameras that can place complex chips. Then the
factory will check the solder point using X-ray machines.
