• 35, 1st Main Rd, Munireddy layout, Bandepalya, Garvebhavi Palya, Bengaluru, 560068

Social

complex assemblies

Metal BGA

Electronics have become essential to daily life. Everything from refrigerators to military aircraft contains electronics. Today’s critical advanced assembly challenges mainly fall into three categories: performance, usability and productivity. To build and visualise product designs quickly and economically, engineers must address all these challenges.

On the other hand, manufacturing techniques are becoming more advanced and aesthetics are increasingly in demand. Project lifecycles and budgets are constrained. Sometimes, these constraints mean that DFM standards are overlooked in PCB design. For example, if the PCB has to fit in a box of fixed dimensions, the PCB design has to be tweaked accordingly. Or, components with different reflow profiles may be used on the same sid

Newer design houses or inexperienced engineers and designers may be prone to these mistakes. But not validating designs with tool and industry standards is bad practice. Here are just a few examples:

Pad mismatch

 If the copper termination pad separates partially or completely from the board, it can be hard to identify the fault; the pad may look intact as the solder usually remains attached to the component. The cause is usually mechanical strain that begins during testing, manufacturing, vibration while being transported or even when connectors are attached. PCB performance is impaired and performance is inconsistent. Extensive or even destructive testing may be required to positively identify the cause. Podrain follows a painstaking process to minimise the risk of damage from pad mismatch at each step.

No silkscreen. 

The silkscreen does not impact the electrical functionality of a PCB, but it is still extremely valuable as it provides essential information when assembling the PCB. It provides simple visual feedback that helps to catch deeper problems. It is not merely for aesthetic purposes. It is information that should not be separated from the board. Unique ID numbers, warning symbols, certifications etc. should be displayed on the board. At Podrain, we treat correct and comprehensive silkscreens as an integral part of the PCB.

THT vs. SMT components. 

When SMTs were developed in the 1980s they were expected to completely replace THTs. But THTs and SMTs are not always interchangeable. THTs offer reliable and useful in test and prototyping applications where frequent manual adjustments and replacements are needed. But SMTs are almost always more efficient and cost-effective. Podrain’s extensive experience in a wide range of applications gives us the expertise to know which type of components to use for a given project.

Incorrect polarity marking. 

To prevent polarised component packages from being inverted during assembly machine setup or manual soldering, accurate polarity marking is critical. It is only necessary for land patterns that have a specific rotation during assembly. Incorrect polarity markings can cause equipment damage, short-circuiting, serious injury, fires or even explosions. Podrain follows stringent Post Assembly Inspection Process protocols to visually validate that assembly insertion is done correctly

Incorrect component separation. 

Most designers are used to PCB clearance rules for spacing between traces in a single layer. However, many design houses overlook PCB clearance between layers. Today’s circuit designs often involve a single PCB with power and controls on the same substrate. This may put high-voltage traces close to low-voltage signals, creating a risk of arcing. The resulting sparks can permanently damage the port of the low-voltage component. Podrain designers and engineers keep ourselves up to date on the latest IPC-2221B design standards to ensure optimum manufacturability with minimum risk.

Podrain’s customers have brought us some interesting design challenges.

A top manufacturer of electric vehicle charging stations found that the PCBA yield was below 90%, lower than expected. The company approached Podrain to investigate. The issue was all the more challenging because the assembly was ROHS. Planning and finding the right profile, especially on a PCB that uses BGA + LGA, is an art.  By devoting our experienced people to solve this, we iterated through a range of 11 temperature profiles in a reflow oven within just 2 days to find the solution.

Another customer set us the challenge of setting the right profile for a board designed with a heavy BGA connector having multiple ceramic BGAs, including micro BGAs, on a 2mm thick PCB. The issue is these kind of connectors use very high temperature for soldering. 265 degree Celsius plus is needed for soldering but a normal BGA can tolerate only 245 to 255 degree Celsius. We designed and conducted multiple trials by changing the solder paste for each profile. After 15-20 trials supported by some fixtures, we were able to determine the best profile for the customer’s board.

Podrain has solved many such complex assembly design challenges for our customers.

Read More

The Art of Quick Turn Prototype Manufacture – Some learnings

As a PCB assembly and manufacturing unit, we face several challenges in ensuring we can meet the turnaround time our clients ask for while still delivering a quality product. This is a short post on the challenges we face and how we solve them.

6 M framework based thinking helped Podrain find solutions for quick turnaround manufacture

Managing Part Availability Delays

Every manufacturing organization has dealt with issues in this area. The critical part is held up in customs. A normally reliable supplier doesn’t have stock just now. The wrong part got shipped. The list of such issues can be long. Our clients purchase the parts for us in most cases because we are a “job-work” oriented partner, but there are many occasions when the part isn’t available on time but the end date to finish the manufacture is the same!

We’ve seen clients work hard through the day and the part reaches us at the end of the regular workday. We have adapted by having a 3 shift operation in place so that we can take up the order manufacture at any time and ensure client timelines are met. We also ensure that our strongest team members are available on the late shift. It can be tough working late at night on an important order and we put our toughest people on the job to make sure it gets done right.

There are some consumables, that we must order and here we invest in supplier relationships. Our stencil suppliers, for instance, deliver within a few hours because they know they can trust our volume commitments and payment cycles.  

Kit Condition Checks First

For larger clients who have their own kitting teams, 99% of the kits arrive in good condition and we can start manufacture immediately. However, many of our clients are startups or design houses that are still experimenting. The parts are directly shipped to us without kitting checks at the client’s end. 

We solve this by frontloading our effort in checking kits. Where other manufacturers would ask two people to run kit checks, we allocate 6 people. And we work with the client to solve for deficiencies right away – if there is a part shortfall can we run a smaller batch? Is there additional testing we can do on a smaller batch, while we wait? Is there an alternate part or source we have seen that we can connect them to? We work flexibly with our partners to ensure their goal is met.

Data Package Standardization

In the past when we accepted all client data packages as-is, we would spend a day verifying the documents – gerbers, assembly drawings, additional assembly instructions, etc. – and then mapping them to our process to ensure there were no misses. Working with our clients we realized many of them were flexible on giving us this information in a format that we requested. This saves us time and ensures we can follow a Total Quality Management process even within a 48 or 72-hour manufacturing turn. 

We’ve used the 6 M framework – Manpower, Method, Machine, Material, Milieu and Measurement to think through problems and find some of these solutions. I highly recommend this to anyone working in Manufacturing or even in other industries.  

That’s it for this month. I’ll write again with more of our learnings next month. 

If you want to know more about Podrain and our electronics manufacturing services contact us and we will get back to you at the earliest

Read More
Solder Paste

Solder Paste Choice

Solder paste printing attaches surface mount devices to printed circuit boards. Over 70% of Surface Mount Technology defects are driven by solder problems.* The choice of solder paste can make a huge difference. As devices and their components become smaller, the solder connections are also correspondingly finer. Its hard to fill apertures for these small devices with coarser type 3 solder paste. Type 2 solder paste is almost never used on Printed Circuit Boards. Rather, it features in power and industrial products where the chip package is bigger.  

 

Until 2017, India had easy access only to type 3 solder paste which has 25-45 microns powder size. While it is possible to use type 3 solder paste for lead pitch between 0.3mm and 0.02mm , the reliability and durability of the boards reduces. Type 4 solder paste yields better results in our experience. We also use a Solder Paste Inspection system to ensure the right amount has been used.

 

Podrain has been sourcing and utilising type 4 solder paste, even though it entails a 20%-30% higher cost for the past 4 years. Now, we see an across the industry move to Type 4 solder paste  and even the manufacture of Type 3 solder paste is coming down. We are currently evaluating switching to type 5 solder paste which has a powder size of 15-25 microns for components that need to go on the smallest PCB’s. 

 

So when you are looking for a provider to make your PCBA’s, go beyond looking at the machines on the assembly line, and ask what solder paste is used. 

 

*Biemans. 2011. “5D solder paste inspection merits beyond 3D technology.” Global SMT and Packaging 8-13 

References

https://blog.gotopac.com/2020/03/13/solder-paste-types-powder-sizes-for-smt-dispensing/

https://scholarworks.rit.edu/cgi/viewcontent.cgi?article=10208&context=theses

 

 

Read More