🧱 SMT Metal Copper Sheets (blocks/jumpers) for High Current PCB

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Introduction

To carry high current using common FR-4 PCB board these common solutions are used:

  • Make track or polygon wider
  • Use thicker copper (like 2 oz (70 um), 3 oz (95 um) or more)
  • Use several parallel layers of multilayer board (2L, 4L, 6L or more)
  • Remove mask and place soldering paste to increase bus height
  • Use additional copper wire on high-current polygons

New Solution

This is an SMT (surface mounted) copper (actually it could be brass) sheet (block), that can be used with ordinary PCB as component (you can call it jumper):

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As you can see that these blocks could be in different sizes, bottom side is fully flat, but top side has fillet corners:

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The main Chinese companies, that produce special metal jumpers is YIYUAN(怡远), DGBZ(东莞博众), STEIPU(斯泰普). Components (blocks) provided in reel-tape, which makes it ideal for your board when using P2P machine for assembly:

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Expected Resistance

Datasheet not declare resistance of the sheets (jumpers), which make choosing hard. Plus you can place it in different way, so let's introduce two concepts:

SR Series ResistancePR Parallel Resistance

ImageSo, to be more clear I decided to calculate worst-case resistance of the each YMT block.

For example, the first one MPN YTC-M8518-BN has sizes L = 8mm, W = 5 mm, H = 1.8mm, so if material (brass) electrical resistivity ρBrass=0.07 Ohm*m the resistances if following:

  • SR = 62.22 uOhm
  • PR = 24.31 uOhm

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Expected Power Losses

Let's take one of the SMT sheet blocks, let's say we have YTC-M8518-BN, in this case we have such power losses:

😯 The real power losses will be higher due to metal resistance increasing when heating!

SR

For I=100A current power losses is P=0.622W.

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PR

For I=100A current power losses is P=0.243W.

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Real Using Examples

Evaluation Board (DevBoard)

Battery Management System (BMS)

The only one board I've seen where used similar metal blocks is development board from Infenion:That's not exact as blocks, but the idea is the same (as you can see it also like like brass):
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Inverter (Solar)

This is a high-power inverter with solar inputs. As you can small block used to decrease power losses. Footprint consist 3 pads instead of one big.
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Conclusions

  • Due to low price and easy use consider using metal SMT blocks for high-current applications
  • Because it's packaged in reel you can use P&P machine for automatic assembly
  • I supposed more manufacturer should do simple things like this, so waiting for tinned copper blocks with different sizes
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