一.何為短槽

     短槽通常定義:槽長小於2倍槽寬      如：槽長1.8mm,槽寬1.0mm

二.為什麼要加短槽加引孔呢

       短槽孔在鑽孔時孔易偏斜導致槽長偏短, 當槽長寬比越小,則受力越不均勻,在鑽第2個孔時,鑽頭兩邊受力不均勻再加上是順時針旋轉，會導至第2個孔往逆時針方向偏轉且變短(如下圖）

   短槽偏位問題如何解決呢，在我們PCB行業最佳作法是在鑽槽孔之前，先在槽孔兩端2個小孔(如下圖).

  在PCB行業已有很多短槽加工方法

  具體方法請連結：PCB鑽孔--超短坑槽的加工方法

                            機械鑽孔中的短槽孔加工技術

                           短槽孔加工技術

三.加短槽引孔實現原理

 求解思路

1.已知短槽寬1.0mm與短槽2點座標
2.求出槽長=槽中心距0.8 + 槽寬1.0=1.8mm
3.求出引孔大小=(1.8-0.2)/2 =0.8mm
(0.2為2個引孔間距, 孔徑向下取整為鑽刀大小)
4.求出短槽的線拉伸距離=
（槽長1.8- 引孔大小0.8mm）-槽中心距0.8mm=0.2mm
5.求引孔座標，在短槽2點座標為一條線，在的基礎上拉伸0.2mm即可,每邊各拉0.1mm，即可得到引孔座標（下面程式碼有提供線拉伸函式）

四.C#簡易程式碼實現:

 1.加短槽程式碼

            #region
 
 短槽加引孔  ydkdrl
            List<gL> SlotList = glayer.Llist.Where(tt => ((calc2.p2p_di(tt.ps, tt.pe) + tt.width * 0.001) / (tt.width * 0.001)) < 2).ToList();
            if (SlotList.Count() > 0)
            {
                if (!g.Check_Layer_Exist("ydkdrl")) g.CreateLayer("ydkdrl");
                g.SetAffectedLayer("ydkdrl");
                for (int i = 0; i < SlotList.Count; i++)
                {
                    double HoleSize = ((int)(Math.Floor(((calc2.p2p_di(SlotList[i].ps, SlotList[i].pe) * 1000 + SlotList[i].width)) * 0.5 / 50)) * 50);
                    SlotList[i] = calc2.l_extend(SlotList[i], (SlotList[i].width - HoleSize) * 0.001);
                    addCOM.pad(SlotList[i].ps, HoleSize);
                    addCOM.pad(SlotList[i].pe, HoleSize);
                }
                g.SetAffectedLayer("");
            }
            #endregion

  2.線拉伸函式(關鍵在於此函式實現)

     
        /// <summary>
        /// 線Line拉伸 
        /// </summary>
        /// <param name="l"></param>
        /// <param name="extend_val">拉伸數值</param>
        /// <param name="type_">0兩端拉伸  1起點拉伸  2端點拉伸</param>
        /// <returns></returns>
        public gL l_extend(gL l, double extend_val, byte type_ = 0)
        {
            gL tempL = l;
            double angle_ = p_ang(l.ps, l.pe);
            if (type_ == 1)
            {
                tempL.ps = p_val_ang(l.ps, extend_val, p_ang_invert(angle_));
            }
            else if (type_ == 2)
            {
                tempL.pe = p_val_ang(l.pe, extend_val, angle_);
            }
            else
            {
                extend_val = extend_val * 0.5;
                tempL.ps = p_val_ang(l.ps, extend_val, p_ang_invert(angle_));
                tempL.pe = p_val_ang(l.pe, extend_val, angle_);
            }
            return tempL;
        }
        

         /// <summary>
        /// 求方位角
        /// </summary>
        /// <param name="ps"></param>
        /// <param name="pe"></param>
        /// <returns></returns>
        public double p_ang(gPoint ps, gPoint pe)
        {
            double a_ang = Math.Atan((pe.y - ps.y) / (pe.x - ps.x)) / Math.PI * 180;
            //象限角  轉方位角   計算所屬象限   並求得方位角
            if (pe.x >= ps.x && pe.y >= ps.y)  //↗    第一象限
            {
                return a_ang;
            }
            else if (!(pe.x >= ps.x) && pe.y >= ps.y)  // ↖   第二象限
            {
                return a_ang + 180;
            }
            else if (!(pe.x >= ps.x) && !(pe.y >= ps.y))  //↙   第三象限
            {
                return a_ang + 180;
            }
            else if (pe.x >= ps.x && !(pe.y >= ps.y))  // ↘   第四象限
            {
                return a_ang + 360;
            }
            else
            {
                return a_ang;
            }
        }
        
        
        /// <summary>
        /// 求增量座標
        /// </summary>
        /// <param name="ps">起點</param>
        /// <param name="val">增量值</param>
        /// <param name="ang_direction">角度</param>
        /// <returns></returns>
        public gPoint p_val_ang(gPoint ps, double val, double ang_direction)
        {
            gPoint pe;
            pe.x = ps.x + val * Math.Cos(ang_direction * Math.PI / 180);
            pe.y = ps.y + val * Math.Sin(ang_direction * Math.PI / 180);
            return pe;
        }
        
        

  3.點線資料結構

    /// <summary>
    /// 點  資料型別 (XY)
    /// </summary>
    public struct gPoint
    {
        public gPoint(gPoint p_)
        {
            this.x = p_.x;
            this.y = p_.y;
        }
        public gPoint(double x_val, double y_val)
        {
            this.x = x_val;
            this.y = y_val;
        }
        public double x;
        public double y;
        public static gPoint operator +(gPoint p1, gPoint p2)
        {
            p1.x += p2.x;
            p1.y += p2.y;
            return p1;
        }
        public static gPoint operator -(gPoint p1, gPoint p2)
        {
            p1.x -= p2.x;
            p1.y -= p2.y;
            return p1;
        }


    }
     /// <summary>
    /// Line 資料型別
    /// </summary>
    public struct gL
    {
        public gL(double ps_x, double ps_y, double pe_x, double pe_y, double width_)
        {
            this.ps = new gPoint(ps_x, ps_y);
            this.pe = new gPoint(pe_x, pe_y);
            this.negative = false;
            this.symbols = "r";
            this.attribut = string.Empty;
            this.width = width_;
        }
        public gL(gPoint ps_, gPoint pe_, double width_)
        {
            this.ps = ps_;
            this.pe = pe_;
            this.negative = false;
            this.symbols = "r";
            this.attribut = string.Empty;
            this.width = width_;
        }
        public gL(gPoint ps_, gPoint pe_, string symbols_, double width_)
        {
            this.ps = ps_;
            this.pe = pe_;
            this.negative = false;
            this.symbols = symbols_;
            this.attribut = string.Empty;
            this.width = width_;
        }
        public gPoint ps;
        public gPoint pe;
        public bool negative;//polarity-- positive  negative
        public string symbols;
        public string attribut;
        public double width;
        public static gL operator +(gL l1, gPoint move_p)
        {
            l1.ps += move_p;
            l1.pe += move_p;
            return l1;
        }

五.加短槽引孔指令碼UI

 六.加短槽效果