Testing ICs+PCBs

An introduction to PCB

If you are wondering what PCB is and what to do with it, keep reading! PCB is Printed Circuit Board. A structure with electrical circuitry made up of metal wires (traces) and bigger areas of metal (planes).

We use PCB to support and give a pathway to its electronic components. It is used in different devices.

In other words, PCB is a board used to connect electronic components together and it is in almost every computer and electronic device today.

A great company that works with PCB is QueenField. It works with integrated circuits, such as ASIC & FPGA, described in VHDL & Verilog; verified and synthesized with open source tools; and printed with open standard cells. But it also works with drawing PCBs, printing PCBs, verifying PCBs and testing ICs+PCBs. We will talk more about QueenField at the end.

More than 5 year experience in Hardware and Software Systems

Integrated Circuits (ASIC & FPGA) described in VHDL & Verilog; verified and synthesized with open source tools; and printed with open standard cells.
Printed Circuits Boards drawn, printed, verified and tested with open source tools.

Testing ICs+PCBs

We offer Printed Circuit Board and Integrated Circuit Mask Layouts tested with open source tools such as KiCad or gEDA.

A while ago, when electronic circuits were simpler, manual visual inspection, known as MVI, was enough to recognize issues. For example, short circuits, interrupted traces, missing components…

But this technique, MVI, had lots of problems related to human mistakes while performing the operations. Because of that there were many not detected problems as well as problems discovered at an advanced stage of the design. And these modifications became really expensive.

The next step was to automatize the inspection process. How? Just using the AOI or Automated Optical Inspection method, a proven inspection technique. It is used during welding preflow and welding postflow.

Another technique is the AXI: Automated X-ray Inspection. It allows to inspect through the package and through the multilayer PCBs with lots of components.

The PCB has to experience an adequate test, performed on the final assembled circuit.

Objectives

There are a few objectives of PCB testing which have to be achieved by the set of test that are going to be performed:

Component polarity, alignment, placement and orientation
Environmental test, especially when PCBs operate in humid environments
Quality of hole wall
Cleanliness
Welds quality
Electrical conductivity
Mechanical resistance

Types of PCB Testing Methods

We are going to talk about 7 different types of PCB Testing Methods: in-circuit testing, flying probe testing, automated optical inspection, burn-in testing, X-ray inspection, functional testing, and other functional tests.

In-circuit testing

In-circuit test (ICT) is an influential tool for Printed Circuit Board test. By using this method you will be able to approach the circuit intersection and estimate the performance of the components. You are going to be able to measure parameters like resistance and capacitance. If you use an in-circuit test, it is possible to comprehend the PCB and to check that the circuit has been manufactured in the right way.

Flying probe testing

This is an option less expensive than the previous one. It checks for the following things:

Opens
Shorts
Resistance
Capacitance
Inductance
Diode issues

Something you have to keep in mind while using this method is that a PCB flying probe does not activate the board.

Automated optical inspection (AOI)

This can be really useful in order to detect issues early, so you make sure you fix what needs to be fixed as soon as possible. However, it does not activate the board and it may not cover all part types. This is why we should not rely on an automated optical inspection and this is the reason why we have to use AOI with other tests. Some useful combos are the following:

AOI and flying probe
AOI and in-circuit test (ICT)
AOI and functional testing

Burn-in testing

This is a more extreme type of PCB testing. It is supposed to detect early failures and form load capacity. Burn-in testing can destroy the parts that are being tested. This is because of its high intensity. It usually uses its maximum-specified capacity and the power can run past the board for 48 to 168 hours.

The main goal of burn-in testing is to prevent embarrassing and dangerous product launches before they are seen by customers.

X-ray inspection

During this test, an X-ray technician looks for defects early while manufacturing process, and this technician views:

Solder connections
Internal traces
Barrels

Functional testing

Probably the best way to prove that your product will power up. It takes time, so if you want to get your product quickly, you better look for other options. But if you have the time, the quality of this technique will save you money.

The requirements for this test are:

External pieces of equipment
Requirements for UL, MSHA, and other standards
Fixtures

Other functional tests

You can check your PCB using other types of functional test, such as solderability test, PCB contamination testing, micro-sectioning analysis, time-domain reflectometer (TDS), peel test, and solder float test. This type of test demonstrates the behaviour of the PCB in the product’s end-use environment.

Some advantages of functional PCB testing include simulating the operating environment, minimizing customer cost, eliminating the need for expensive system tests, checking product functionality, and detecting incorrect component values, functional errors, and parametric mistakes. It also pairs well with other tests, such as ICT or flying probes.

QueenField’s services

We already introduced you to QueenField. But there is so much more you should know!

Firstly, the hardware/software engineer behind the company, Paco Reina Campo. He founded QueenField and has been its electronic engineer since September 2004. Also, he has 5 years of experience in hardware and software systems. He specialized in digital design and verification (ASIC, FPGA), with emphasis on Hardware Description Languages (Verilog, VHDL). He is focused on the design, verification, and simulation of Integrated Circuits and Printed Circuit Boards.

If you still have doubts about choosing QueenField, you should know all of its advantages: it has mixed implementations (digital designs implemented in VHDL and System Verilog), UVM and Formal Verification (digital designs simulated and verified using universal and formal methods) and 100% Open Hardware (open source hardware descriptions and open source tools used).