ドキュメントのセクション

基板トレース幅計算ツール (IPC-2221/IPC-2152)

POSThttps://rftools.io/api/py/v1/calculate

スラッグ trace-width-current。IPC-2221およびIPC-2152に従って、電流容量の最小PCBトレース幅を計算してください。抵抗、電圧降下、消費電力を求めましょう。無料ですぐに結果が得られます。

入力

これらの入力を、表示されている単位ですべて inputs に入れて送ってください。ほとんどは必須で、1 つでも欠けた呼び出しは拒否され（400）、費用はかかりません。省略しても計算できる入力は、表示されている既定値を使います。範囲外の入力も計算され、来歴で示されます。

trace-width-current の入力
名前	単位	範囲	既定値	説明
current数値	A	0.01 … 100	1	トレースを流れるRMS電流
copperWeight数値	oz	0.5 … 4	1	銅の厚さ (1 oz = 35 μm = 1.378 mil)
tempRise数値	°C	1 … 100	10	周囲温度を超える温度上昇の許容値
traceLength数値	mm	1 … 10000	100	トレースの長さ (抵抗/電圧降下用)
isExternal数値	なし	0 … 1	1	幅と温度上昇が同じでも、内層は外層よりも流せる電流が少なくなります次のいずれか：1 外層 · 0 内層
traceWidth数値	mm	0.01 … 100	0.5	実際に描くトレース幅。規格チェックはこの幅で判定し、直流抵抗、電圧降下、電力損失もこの幅で計算します。最小幅の計算には使いません
boardThickness数値	mm	0.2 … 6	1.6	基板全体の厚さ。この基板での幅（rftools の熱モデル）だけが使います。モデルの検証範囲は1.4～3.2mmです
planeDistance数値	mm	0 … 6	0	トレースとその下にある最も近いベタの銅プレーンとの間の誘電体。0は銅プレーンなし。この基板での幅だけが使います
planeCopperWeight数値	oz	0.5 … 2	0.5	その銅プレーンの銅の重量（1オンスあたり35µm）。この基板での幅だけが、銅プレーンがある場合にのみ使います
standard数値	なし	0 … 1	0	電流を照合するチャート: IPC-2221A の外層または内層の曲線、またはすべての導体に適用する IPC-2152 の保守的なチャート次のいずれか：0 IPC-2221A 図 6-4 · 1 IPC-2152 図 5-1

出力

values に名前ごとに返されます。上限がない値や定義されない値は null です。

trace-width-current の出力
フィールド	単位	説明
width2221mm	mm	最小幅 (IPC-2221)
width2152mm主要値	mm	最小幅 (IPC-2152 図5-1)
resistance	Ω	直流抵抗値 (設計幅)
voltageDrop	V	電圧降下 (設計幅)
powerDiss	W	電力損失 (設計幅)
inChartRange	なし	IPC-2152 図5-1 の範囲内
widthBoardMm	mm	最小幅 (この基板、熱モデル)
inModelRange	なし	熱モデルの範囲内
limitCurrent	A	電流の制限値
limitPercent	%	制限値に対する割合
minTraceWidth	mm	適合幅

呼び出し方

計算：1 回の呼び出し、リクエストとレスポンスの全体、そのエラー。
バッチ：この計算ツールをほかと組み合わせて、または掃引を、1 リクエストで。
目標値からの逆算：出力を目標値にする入力の値。

curl -X POST https://rftools.io/api/py/v1/calculate \
  -H "X-API-Key: $RFTOOLS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "slug": "trace-width-current",
    "inputs": {
      "current": 1,
      "copperWeight": 1,
      "tempRise": 10,
      "traceLength": 100,
      "isExternal": 1,
      "traceWidth": 0.5,
      "boardThickness": 1.6,
      "planeDistance": 0,
      "planeCopperWeight": 0.5,
      "standard": 0
    }
  }'

import rftools

client = rftools.Client()  # reads RFTOOLS_API_KEY, or the key `rftools login` saved

result = client.calculate("trace-width-current", {
    "current": 1,
    "copperWeight": 1,
    "tempRise": 10,
    "traceLength": 100,
    "isExternal": 1,
    "traceWidth": 0.5,
    "boardThickness": 1.6,
    "planeDistance": 0,
    "planeCopperWeight": 0.5,
    "standard": 0,
})
print(result.values)
print(result.warnings, result.provenance.formula_ref)

const response = await fetch("https://rftools.io/api/py/v1/calculate", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.RFTOOLS_API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "slug": "trace-width-current",
    "inputs": {
      "current": 1,
      "copperWeight": 1,
      "tempRise": 10,
      "traceLength": 100,
      "isExternal": 1,
      "traceWidth": 0.5,
      "boardThickness": 1.6,
      "planeDistance": 0,
      "planeCopperWeight": 0.5,
      "standard": 0
    }
  }),
});
console.log(response.status, await response.json());

package main

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"os"
)

func main() {
	body := []byte(`{
	  "slug": "trace-width-current",
	  "inputs": {
	    "current": 1,
	    "copperWeight": 1,
	    "tempRise": 10,
	    "traceLength": 100,
	    "isExternal": 1,
	    "traceWidth": 0.5,
	    "boardThickness": 1.6,
	    "planeDistance": 0,
	    "planeCopperWeight": 0.5,
	    "standard": 0
	  }
	}`)
	req, err := http.NewRequest("POST", "https://rftools.io/api/py/v1/calculate", bytes.NewReader(body))
	if err != nil {
		panic(err)
	}
	req.Header.Set("X-API-Key", os.Getenv("RFTOOLS_API_KEY"))
	req.Header.Set("Content-Type", "application/json")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	out, _ := io.ReadAll(res.Body)
	fmt.Println(res.Status, string(out))
}

application/json

{
  "slug": "trace-width-current",
  "values": {
    "width2221mm": 0.30038652083330486,
    "width2152mm": 0.7814374629086279,
    "resistance": 0.10433004926108375,
    "voltageDrop": 0.10433004926108375,
    "powerDiss": 0.10433004926108375,
    "limitCurrent": 1.4468880626650513,
    "limitPercent": 69.11384686926509,
    "minTraceWidth": 0.30038652083330486,
    "inChartRange": 1,
    "widthBoardMm": 0.3021150755977321,
    "inModelRange": 1
  },
  "warnings": [],
  "errors": [],
  "provenance": {
    "method": "calculator:trace-width-current",
    "version": "api@3f2c1a9b04de",
    "formulaRef": "IPC-2221A (May 2003) §6.2, Figure 6-4 (the chart of IPC-2221, February 1998), through its published fit; IPC-2152 (August 2009) §5, Figure 5-1; the board-specific width: rftools thermal model (board-specific), fitted to its own 2-D solver and checked against Brooks & Adam (2015), Jouppi (2010) and Olson (2010)",
    "assumptions": [
      {
        "code": "ipc-2221-fit",
        "text": "The IPC-2221 width is IPC-2221 Figure 6-4 through its published fit A = (I/(k·ΔT^0.44))^(1/0.725), with A in mil², k = 0.048 for an external layer (chart A) and 0.024 for an internal one (chart C). Chart A draws 10 to 100 °C and chart C 10 to 45 °C, both to 700 sq mil; the curves include IPC-2221’s 10 % derating, and its note 2 (a further 15 % for boards 0.8 mm or thinner or copper 108 µm or thicker) is not applied."
      },
      {
        "code": "ipc-2152-figure-5-1",
        "text": "The IPC-2152 width is read on IPC-2152 Figure 5-1, the chart IPC-2152 recommends for internal and external conductors in all environments, through the same fit with k = 0.024 on either layer. It is the conservative answer for a board about which nothing else is known: IPC-2152’s detailed method, which narrows the trace for the board’s thickness and a copper plane under it, is not applied."
      },
      {
        "code": "steady-state-dc",
        "text": "Steady DC (or RMS) current in a single trace: pulsed currents, skin effect and heating from neighbouring traces are not modelled."
      },
      {
        "code": "copper-weight",
        "text": "Copper is 35 µm (1.378 mil) thick per ounce, and the trace cross-section is a rectangle of that thickness."
      },
      {
        "code": "standards-check-chart",
        "text": "The standards check reads the drawn width on IPC-2221A Figure 6-4’s curve for the layer, or on IPC-2152’s conservative Figure 5-1, which is IPC-2221’s internal curve, for either layer. It applies neither the further 15 % derating Figure 6-4 suggests for boards 0.8 mm thick or less and copper 108 µm thick or more, nor IPC-2152’s detailed charts and modifiers."
      },
      {
        "code": "resistance-at-temperature",
        "text": "Resistance, voltage drop and power are for the drawn trace width, with ρ = 1/58 Ω·mm²/m (IEC 60028, 1.7241×10⁻⁸ Ω·m) at 20 °C and α = 0.00393 /°C, evaluated at a 25 °C ambient plus the allowed rise."
      },
      {
        "code": "thermal-model-own-method",
        "text": "The board-specific width is the rftools thermal model (board-specific): the site's own steady-state model of a long trace on an FR-4 board in still air, with an optional copper plane under it. It is not IPC-2152 and does not read IPC-2152's charts; it is a closed form fitted to a committed 2-D solver, which is checked against published results (Brooks & Adam 2015; Jouppi 2010; Olson 2010)."
      },
      {
        "code": "thermal-model-fr4",
        "text": "The laminate is FR-4, conducting 0.8 W/(m·K) in the plane of the board and 0.3 W/(m·K) through it (Graebner 1995; Azar & Graebner 1996). A laminate that conducts less runs hotter."
      },
      {
        "code": "thermal-model-still-air",
        "text": "The board is horizontal, in still air at sea level. Its faces lose heat by natural convection (the McAdams horizontal-plate correlations, over the 51.2 mm length of the IPC-TM-650 2.5.4.1A test board) and by radiation, with an emissivity of 0.9 for the laminate and 0.1 for the bare copper trace. Forced air, an enclosure and other orientations are not modelled."
      },
      {
        "code": "thermal-model-long-trace",
        "text": "The trace is long and alone. Heat drawn off through pads, vias and leads at its ends, and heat from neighbouring traces and components, are not modelled; a short trace with heat-sunk ends runs cooler."
      },
      {
        "code": "thermal-model-plane",
        "text": "An internal trace lies at the middle of the board's thickness. A plane is one solid copper layer under the trace, across a 76.2 mm (3 in) wide board, the stated distance of dielectric below the trace. A plane above the trace, a second plane, or a plane cut away under the trace is not modelled."
      },
      {
        "code": "thermal-model-margin",
        "text": "The board-specific width includes a 15 % margin for the model's measured disagreement with published data: it is the width at which the model's rise is the allowed rise divided by 1.15."
      },
      {
        "code": "thermal-model-heat",
        "text": "The model's Joule heat uses the copper resistivity of IPC-TM-650 2.5.4.1A, 10.827 Ω·cmil/ft at 25 °C for 1 oz and heavier copper and 11.529 Ω·cmil/ft for lighter, rising 0.393 % per °C. The resistance and power outputs keep 1/58 Ω·mm²/m."
      },
      {
        "code": "thermal-model-ambient",
        "text": "The board-specific width is computed at a 25 °C ambient, the temperature IPC-TM-650 2.5.4.1A tests at; the allowed rise is above that ambient."
      },
      {
        "code": "thermal-model-range",
        "text": "Outside the model's validated range (Width 0.25–5.1 mm (internal from 1.27 mm), copper ½–3 oz, board 1.4–3.2 mm, a plane from 0.1 mm under the trace to where it fits, plane copper ½–2 oz, rise 5–100 °C, ambient 0–85 °C) the board-specific width is still reported, flagged with a warning naming the bound. On boards thinner than 1.4 mm, IPC-2152's published thickness data show traces running hotter than the model predicts, so the IPC-2152 Figure 5-1 width is the one to use there."
      }
    ],
    "validRange": {
      "status": "inside",
      "bounds": {
        "current": {
          "min": 0.01,
          "max": 100,
          "unit": "A"
        },
        "copperWeight": {
          "min": 0.5,
          "max": 4,
          "unit": "oz"
        },
        "tempRise": {
          "min": 1,
          "max": 100,
          "unit": "°C"
        },
        "traceLength": {
          "min": 1,
          "max": 10000,
          "unit": "mm"
        },
        "isExternal": {
          "min": 0,
          "max": 1,
          "unit": ""
        },
        "traceWidth": {
          "min": 0.01,
          "max": 100,
          "unit": "mm"
        },
        "boardThickness": {
          "min": 0.2,
          "max": 6,
          "unit": "mm"
        },
        "planeDistance": {
          "min": 0,
          "max": 6,
          "unit": "mm"
        },
        "planeCopperWeight": {
          "min": 0.5,
          "max": 2,
          "unit": "oz"
        },
        "standard": {
          "min": 0,
          "max": 1,
          "unit": ""
        }
      },
      "outside": [],
      "model": {
        "description": "IPC-2152 Figure 5-1 through I = 0.024·ΔT^0.44·A^0.725, checked against IPC-2221 (1998) Figure 6-4 chart C (the same chart) at 10 to 45 °C and up to 700 sq mil: the cross-section is within −3.5 % to +4.4 % of 12 chart readings, and 11.3 % short at 10 °C and 700 sq mil",
        "worstCaseError": 0.12,
        "inside": true
      },
      "models": [
        {
          "description": "IPC-2152 Figure 5-1 through I = 0.024·ΔT^0.44·A^0.725, checked against IPC-2221 (1998) Figure 6-4 chart C (the same chart) at 10 to 45 °C and up to 700 sq mil: the cross-section is within −3.5 % to +4.4 % of 12 chart readings, and 11.3 % short at 10 °C and 700 sq mil",
          "worstCaseError": 0.12,
          "inside": true
        },
        {
          "description": "rftools thermal model (board-specific), a closed-form thermal network fitted to rftools' own committed 2-D solver of the trace's cross-section: Width 0.25–5.1 mm (internal from 1.27 mm), copper ½–3 oz, board 1.4–3.2 mm, a plane from 0.1 mm under the trace to where it fits, plane copper ½–2 oz, rise 5–100 °C, ambient 0–85 °C (the rise before the margin). Inside that range its rise is within 2.81 % of 3,168 solver results",
          "worstCaseError": 0.029,
          "inside": true
        }
      ]
    },
    "computedAt": "2026-09-24T14:05:11.003Z",
    "inputs": {
      "current": 1,
      "copperWeight": 1,
      "tempRise": 10,
      "traceLength": 100,
      "isExternal": 1,
      "traceWidth": 0.5,
      "boardThickness": 1.6,
      "planeDistance": 0,
      "planeCopperWeight": 0.5,
      "standard": 0
    },
    "seed": null,
    "elapsedSeconds": 0.003
  }
}

{
  "detail": [
    {
      "type": "float_parsing",
      "loc": [
        "body",
        "inputs",
        "current"
      ],
      "msg": "Input should be a valid number, unable to parse string as a number",
      "input": "abc"
    }
  ]
}

テキストとして送られた入力。計上はされていません。

{
  "detail": "More than 120 requests in 60 seconds from this address.",
  "errorKind": "rate_limited",
  "limit": 120,
  "windowSeconds": 60,
  "upgradeUrl": "https://rftools.io/pricing/"
}

1 分あたりのリクエストが多すぎます。Retry-After 付き。

同じ入力で計算ツールのページを開く基板トレース幅計算ツール (IPC-2221/IPC-2152)、この値で