🧱 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
  • Using THT custom copper plates (UPD: 10/15/2024)

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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Metal (UPD: 10/22/2024)

The material could be just copper or fusion (just copper is better):

  • Red Copper (Electroplated Matte Tin)
  • Brass H62 (Nickel Plated)
  • Brass (Nickel Plated)

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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Packaging (UPD: 10/22/2024)

Some of these SMT blocks could be in a Bag-packed and some in Tape & Reel (TR). Obviously for P2P machines pay attention that blocks provided in a reel, otherwise it would need manual placement, which cause high assembly price:

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Moreover, in datasheet could be specified two options without different part number, so check or ask distributor about packaging method:

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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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Spot Welding

Pretty long SMT stripes (brass). Most likely they they are cut and placed manually:

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Charger Station (UPD 09/22/2024)

This is a board of the Bluetti AC180P charger station with buuilt-in rechargeable batteries and BMS. Many of the soldered SMT blocks not mounted (DNP), but solder paste still carry an electrical current:

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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 (see packaging method in the datasheet and on distributor page)

  • Metal blocks made of Red Copper (Electroplated Matte Tin) or Brass (Nickel Plated)
  • Opened from mask copper is better cooling, so blocks should be also better cooled by the air

  • I supposed more manufacturer should do simple things like this, so waiting for tinned copper blocks with different sizes

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