You will frequently hear surface mount manufacturers brag about their surface mount lines' performance. And you will almost always hear the acronym "CPH" in these conversations, preceded by an extravagant number. While 100,000 CPH may sound impressive, this is rarely an accurate estimate of the machine's capacity.
Components per hour, or CPH, measures how fast a chip shooter or pick-and-place machine can place components. Because these machines are the bread and butter of the surface mount line, their speed directly influences the line's rate, and subsequently, the cost of the board to be manufactured. Manufacturers of these machines, and the companies that use them, want CPH values to be as large and impressive as possible to try to highlight that their lines can produce more boards, cost effectively. We’ll dig into how CPH values came to be and how they’ve changed.
The Bleeding Speeding Edge
CPH was originally used as a baseline measurement to compare machines and equipment manufacturers. The downside was how this unrealistic (and unhelpful) metric was derived – many PCB assemblers who bought machines advertising 50,000+ CPH found themselves asking the equipment manufacturers how to hit those beautifully advertised numbers. A machine that, at the time, advertised 50,000 CPH was barely getting the throughput to 12,000 CPH, even when running optimally.
So, what was happening? It turns out, the equipment manufacturers (EMs) were measuring how fast a machine could pick a component, then place it in the same spot. The machine didn’t have to move the component to the board like it would during production, nor did it have to place it accurately; CPH was literally a measurement of how fast the machine could physically move the nozzles down, then up, then down. This didn't sit well with buyers, so in 2002, IPC (the international entity that sets the standards for electronics manufacturing) came out with IPC-9850.
Reining It In
IPC-9850 set a more realistic and useful standard of measurement. The machine not only had to pick the components but had to accurately place them on a board. As expected, CPH dropped dramatically. Despite better, faster technology at the turn of the millennium, EMs that once advertised 100,000 components per hour on certain machines more than halved their CPH calculations.
But an issue arose after IPC-9850’s adoption. When EMs advertised the new, lower CPH values, they lost sales to competitors. Why? Unfortunately, there is no standard for what is advertised, so EMs who promoted the outdated, less realistic CPH won more deals. The issue persists to this day, with some EMs continuing to advertise the inflated CPH with the IPC-9850 CPH buried in the fine print.
On A Speed-To-Know Basis
A decade after the adaption of IPC-9850, another problem arose; EMs were publishing IPC-9850 CPH values that were very similar to the inflated, advertised CPH. These IPC-9850 CPH values didn’t seem realistic, so IPC took a closer look.
Because IPC failed to set a standard for what was being placed where, crafty equipment manufacturers were able to inflate the IPC-9850 CPH values by optimizing the machine's test board layout. EMs realized that by placing identical component packages (like 0805 capacitors) the same distance away from each other as the feeders, they could "gang pick-and-place." To put this simply, if there are four heads on a machine, they can pick four components simultaneously and place those four components simultaneously. This allowed for three actions rather than six to ten actions. This created yet another disparity between the specs of the machine and reality.
To respond, IPC released the IPC-9850A standard, saying that, historically, “… placement equipment machine suppliers have selected their own parameters and methodologies to present the specification of their machines’ throughput and accuracy capabilities. The many representations of the information have made the comparisons between placement machines very difficult.” This standard now precisely defines throughput and accuracy evaluation methods, so CPH is much less subjective. As you may have already guessed, this created yet another drop in CPH values and, unfortunately, re-invigorated marketing teams of EMs across the globe to use the inflated, unrealistic CPH rather than the IPC-9850 CPH.
Other Factors To Consider
In addition to braggadocious marketing efforts, there are a few key elements not factored into CPH calculations. Because it’s all about placement speed, the machine is the only aspect factored into the equation. Elements like feeder changes, transport time, machine errors, paste speed, and reflow speed are not considered. To put it simply, CPH is simply a measure of how fast the machine can pick and then place the component (like the name pick-and-place suggests!).
So What’s The Real Number?
There are almost always two numbers used to summarize all of this, and neither is real throughput. When someone says their machine does 200,000 CPH, ask a follow-up question: "What is the IPC-9850 standard CPH?" Better yet, ask what they’re producing at.
As an example, the Juki FX-1R was initially advertised as a 50,000 CPH machine. After IPC-9850 was released, CPH was reduced to 35,000. The current IPC-9850A CPH clocks the device at 25,000. And, after accounting for feeder changes, transfer time, and other minor adjustments throughout the assembly process, the available throughput may be closer to 14,000 CPH.
Of course, CPH is not the only factor that accounts for a surface mount line's efficiency, and (thankfully) machines are getting faster and faster every year. The industry has nearly tripled its machine speeds in the past decade and innovates on every level to increase throughput to match increased demand.
Want to know what we’re producing at? Get in touch with us!